Carbon removal from seawater and other liquids using photoactive compounds

Abstract

A system and method for removing carbon from liquids, such as seawater or other natural bodies of water, is disclosed. The system and method uses photoactivatable compounds that change the pH of the fluid to extract the carbon from the liquid and transfer it to a second environment. The carbon can then be captured, sequestered, formed into products, etc.

Description

[Technical field]

[0001] Cross-references to related topics This application claims priority to U.S. Provisional Patent Applications Nos. 63 / 215,029 (filed June 25, 2021), 63 / 265,515 (filed December 16, 2021), and 63 / 363,844 (filed April 29, 2022), the entire contents of which are incorporated herein by reference.

[0002] The present disclosure provides systems and methods for removing carbon from a carbon-containing liquid, which may be dissolved inorganic carbon, and which may be carbon-containing water, such as seawater, ocean water, or river water. [Background technology]

[0003] Global climate change is a concern worldwide. Since 1880, the Earth's temperature has risen by 0.14°F (0.08°C) per decade, and this rate of warming has more than doubled (0.32°F (0.18°C)) per decade since 1981. This increase in temperature has caused extreme heat, melting of Arctic ocean ice, melting glaciers, changes in rainfall, and changes in the habitats of plants and animals (Climate Change: Global Temperature. NOAA Climate.gov, 2021 [Accessed 18 June 2021]).

[0004] The greenhouse effect naturally keeps the Earth's climate warm and plays a key role in the survival of life on Earth. Greenhouse gases, primarily carbon dioxide (CO2), water vapor (H2O), nitrous oxide (N2O), methane (CH4), ozone (O3), and man-made chemicals such as chlorofluorocarbons (CFCs), reflect infrared radiation (heat) emitted by the Earth, thereby absorbing and re-radiating a portion of the solar radiation that reaches the Earth's atmosphere.

[0005] Carbon dioxide is one of the main components of greenhouse gases. Carbon dioxide is a natural chemical compound that exists as a gas in Earth's atmosphere and in Earth's oceans as dissolved molecules. Sources of atmospheric CO2 are varied, including humans and other organisms that produce CO2 during the breathing process, and other natural sources such as volcanoes, hot springs, and geysers. Carbon dioxide is easily soluble in water. When dissolved in water, carbon dioxide can be converted into CO2, carbonic acid (H2CO3), bicarbonate (HCO3), or phosphate, depending on the pH of the water body. - ), carbonate (CO3 2- The sum of the dissolved components of CO2 constitutes the dissolved inorganic carbon concentration in water (Dodds, et al., Freshwater Ecology, 2002).

[0006] Human (or anthropogenic) activities such as burning fossil fuels (coal, oil, and natural gas), agriculture, and logging are estimated to have emitted 2,000 gigatons of CO2 since 1750 (IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change). These carbon emissions increase the concentration of greenhouse gases such as CO2, impeding the natural warming process of the Earth's climate. CO2 in the atmosphere was 280 ppm before industrialization in 1750, but is now over 400 ppm today. This enhances the greenhouse effect and causes significant global warming (Department of Agriculture, Water, and the Environment. Environment.gov.au. 2021 [Accessed 18 June 2021]).

[0007] Several international treaties and complementary efforts by industry and the public have been signed with the aim of reducing the amount of greenhouse gases in the atmosphere to slow global warming. Achieving this ambitious carbon reduction goal will require the simultaneous deployment of a wide range of efforts, including reducing emissions, increasing the use of renewable energy production, and using carbon removal technologies (IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change). Carbon removal aims to remove carbon from surface reservoirs such as the atmosphere and the upper oceans, and then capture this removed carbon so that it cannot contribute to global warming. Removing carbon from ocean waters in particular has additional benefits. Much of the carbon released by humans into the atmosphere dissolves quickly in the ocean. This increased carbon reduces the pH of seawater through a process called ocean acidification. Ocean acidification has a variety of adverse effects on marine life. Organisms with shells and skeletons made of calcium carbonate, such as oysters and corals, are particularly vulnerable to ocean acidification, which is a major problem for the shellfish fishing industry and a threat to coral, and therefore a threat to the travel industry in general around the world.

[0008] In light of these motivations, it is important to capture CO2 (e.g., anthropogenic CO2). More specifically, there is a need to develop technologies to remove carbon from liquids such as seawater and capture the removed carbon. Such carbon capture is important in efforts to slow or reverse global warming and ocean acidification. Summary of the Invention [Means for solving the problem]

[0009] Several embodiments of systems and methods are disclosed for removing carbon from liquids. In some examples, the removed carbon is transferred to a target stream and recovered for use.

[0010] One example system and method is configured to use a photoactive compound (e.g., a photoacid) disposed in a working fluid interposed between a carbon-containing source liquid and a target stream, the photoactive compound in the working fluid can be used to change the pH of the working fluid to draw carbon out of the source liquid and transfer it to the target stream (e.g., the target liquid or target gas).

[0011] Another example of a system and method is configured to use a photoactive compound to reduce the pH of a carbon-containing source liquid and remove carbon from the carbon-containing source liquid. The photoactive compound can be directly located in the carbon-containing source liquid itself, either in the flow of the carbon-containing source liquid or at a boundary where it contacts the carbon-containing source liquid. Alternatively, the photoactive compound can be embedded in a material that contacts the carbon-containing source liquid, or the photoactive compound can be part of a separate secondary fluid that affects the pH of the carbon-containing source liquid through an ion-permeable membrane.

[0012] Another example of a system and method combines the two aforementioned approaches and is configured to use photoactive compounds to alter the pH of a working fluid and to use photoactive compounds to lower the pH of a source liquid.

[0013] Another example of a system and method is similar to the approach described above, but is configured to use a photoactive compound with the addition of heat to promote carbon flow.

[0014] Another example system and method combines the above approaches and is configured to remove carbon from a source liquid using heating, cooling, and pH changes of the source liquid and / or working fluid, and optionally subsequently recovering the removed and mobilized carbon. [Brief description of the drawings]

[0015] [Figure 1] Figures 1A and 1B are shown. Figure 1A shows the mechanism of removing CO2 from the atmosphere. As shown in Figure 1A, removing CO2 from the surface ocean is similar to direct air capture technology. First, carbon is removed from the surface ocean waters, not from the atmosphere. Carbon equilibrates rapidly (on a time scale of months) in the atmosphere and the surface ocean, so the atmosphere and the surface ocean can essentially be considered as a single reservoir. CO2 emissions can occur anywhere. For example, CO2 emissions can come from a delivery truck driving mid-continent, an airplane flying, or a cargo ship at sea. In all cases, the CO2 is diffused into the atmosphere, with the ocean acting as a sponge for the CO2. When carbon is removed from the ocean, the ocean absorbs as much CO2 from the nearby air as it is removed. The surface ocean quickly equilibrates with the atmosphere (timescales of 3–4 months; Jones, Daniel C., Takamitsu Ito, You Takno, Wei-Ching Hsu, “Spatial and Seasonal Variability of the Air-Sea Equilibration Timescale of Carbon Dioxide,” Global Biogeochemical Cycles 28, no. 11 (November 2014): 1163-78). Figure 1B shows the amount of carbon dioxide in ocean water and the atmosphere by volume. As shown in Figure 1B, ocean water typically contains 99 g / m3 of carbon. Ocean water naturally captures and concentrates CO2 from the air. However, CO2 is dilute in the atmosphere, present at only 0.7 g / m3.

[0016] The disclosed seawater-based carbon removal can be compared to other competing processes, such as direct air capture technology. Existing direct air capture technologies require large fan farms. Furthermore, air-based processes rely on energy-intensive processes to remove carbon from the atmosphere. However, air contains less than 1 gram of CO2 per cubic meter. This means that it would take 1.4 million m3 of air to remove 1 metric ton of CO2. 3 of air must be treated, and separation is a difficult problem: for every molecule of carbon dioxide captured from the air, more than 2,000 molecules of other gases are also captured.

[0017] Advantages of the direct seawater recovery technology disclosed herein include the following: The ocean is a "passive fan farm". Seawater pumping is an established technology. Seawater recovery can have synergies with other industrial processes. Coastal sites for sequestration are abundant. Seawater naturally captures and concentrates carbon from the atmosphere. Typically, one cubic meter of typical seawater contains 140 times more grams of carbon than one cubic meter of air. This means that carbon capture facilities that rely on seawater need to pump less water. Furthermore, the technology to pump seawater at large scale is well established. Thus, the entire surface ocean can be used as a natural passive fan farm instead of a large-scale fan farm. Seawater is also more useful for partitioning problems involving other dissolved gases. Dissolved carbon is not a trace component in seawater, and it is much more abundant than all other dissolved gases in seawater. Seawater's abundance of carbon fundamentally changes the energetics, feasibility, and other key aspects of scaling up carbon capture. Coastal sequestration sites are abundant, especially on the continental shelf. Coastal carbon removal is therefore conveniently located for end users. In addition, there are many power plants and desalination facilities onshore that already pump seawater and could be co-located with the process. There may be various ways to more closely integrate the carbon removal process with these processes. At the very least, the fact that these facilities have been operating at large scale for decades indicates that pumping seawater in large quantities is a proven technology.

[0018] [Diagram 2]2A and 2B are shown. FIG. 2A illustrates a process for carbon removal and capture. As shown in the embodiment shown in FIG. 2A, the inputs are natural seawater and light, and the outputs are decarbonized seawater and carbon dioxide. The process is developed to remove carbon from the environment to reduce the impacts of climate change, meet the needs of the rapidly growing carbon removal market, and accelerate the world's transition to a net-zero carbon economy. In an embodiment, carbon removal credits can be bought and sold by companies and governments that need them to achieve their ambitious climate goals. In its simplest form, the process is designed to take seawater and produce carbon dioxide for future sequestration or utilization. The light-induced chemical reactions in the process are a new approach that can significantly reduce the cost of direct carbon capture technologies. FIG. 2B illustrates a process for acidifying seawater to liberate CO2. As shown in FIG. 2B, most carbon in seawater exists in protonated and hydrated forms. By acidifying seawater, the protonated and hydrated carbon can be converted to CO2, which passively diffuses through the gas contact membrane. The innovation described in this disclosure uses photoactive compounds (e.g., photoactivated reversible photoacids) to make the acidification process energy-efficient and scalable. In this example, the CO2 removal efficiency can exceed 80%. The process does not rely on sorbents or solvents, but sorbents or solvents are optional and may or may not be included. CO2 removal can be immediate and verifiable. The seawater shown may represent other carbon-containing liquids such as those described elsewhere herein, as well as other forms of artificial light.

[0019] [Diagram 3]FIG. 3 illustrates an example of a process using reversible photoacids to acidify seawater induced by light. As shown in FIG. 3, the present technology uses reversible photoacids to acidify seawater. When exposed to light (e.g., blue light at a wavelength of 450 nm), these molecules (photoacids) assume a more acidic conformation that releases protons, which are then used to acidify seawater. The photoacids quickly relax in the dark within seconds to minutes, and are then activated by light to release protons again. Although FIG. 3 illustrates an example of a reversible photoacid, other examples of photoacids can be used as described herein.

[0020] [Figure 4] FIG. 4 shows an exemplary process for removing and capturing carbon from surface seawater. In the first step of the chemical cycle, which is a key component of the process, visible light from the sun or an artificial light source excites a reversible photoacid to release protons. The protons acidify the seawater, lowering its pH and converting dissolved carbon to CO2 gas, which is removed from the seawater by rapid passive diffusion through a gas contact membrane. The CO2 thus produced can be used as is or can be pressurized and purified to the required level for various markets, such as sequestration, or for the production of fertilizer, plastics, cement, methanol, or biofuels. The energy and cost expenditure required to pump water can be further reduced by collocating with a large volume of seawater pumping or discharge facilities, such as power plants or desalination plants, or by using tidal or river currents to obtain the necessary pressure head, and the discharged stream can be converted into a green revenue stream. Meanwhile, the photoacid is pumped from the light to the dark, where it instantly relaxes and returns to its more basic form. This cycle completes by regenerating the alkaline photoacid using used seawater. The carbon-depleted seawater is returned to the ocean, which has the added benefit of helping to combat ocean acidification. Note that DIC stands for Dissolved Inorganic Carbon (composed of H2CO3, CO2 (dissolved in water), HCO3 -, and CO3 2-).

[0021] [Diagram 5] FIG. 5 is a diagram illustrating the diffusion of CO2 from a source liquid stream (also referred to herein as a carbon-containing liquid) to a working fluid and then to a target stream (eg, liquid or gas).

[0022] [Figure 6] FIG. 6 illustrates a multi-step process for concentrating CO2 by diffusing CO2 through a membrane from one working fluid sample at a higher pH condition to another working fluid sample at a lower pH condition.

[0023] [Figure 7] FIG. 7 illustrates the removal of inorganic carbon from a carbon-containing liquid source stream by lowering the pH of the carbon-containing liquid source stream, increasing the partial pressure of carbon dioxide, and converting some or all of the inorganic carbon to CO2 using photoacid embedded in beads or solid surfaces through / over which the carbon-containing liquid passes.

[0024] [Figure 8] Figure 8 illustrates the acidification of a carbon-containing liquid (source liquid stream) by stimulating photoacids embedded in beads or granules to an acidic state with light (A, top), converting some or all of the dissolved inorganic carbon to CO2, and raising the partial pressure of carbon dioxide, which is then transferred to a target stream. The photoacids revert to basic in the absence of light (B, top), thereby increasing the pH of the source liquid stream. The direction of the source liquid flow can be reversed so that the regenerated photoacids are used to acidify the source liquid stream under light (B, bottom), and the stimulated photoacids are regenerated in the dark to a more basic state (A, bottom).

[0025] [Figure 9] FIG. 9 shows a photoacid embedded on the carbon-containing liquid (source liquid flow) side of a gas permeable membrane.

[0026] [Figure 10]FIG. 10 illustrates an example process in which a photoacid attached to the carbon-containing liquid (source liquid stream) side of a gas-permeable membrane can facilitate carbon removal from the carbon-containing liquid, followed by uptake by the target stream. In FIG. 10, "HP" indicates protonated photoacid and "-P" indicates deprotonated photoacid. (a) Fluid on the carbon-containing liquid source side of the membrane contains dissolved inorganic carbon, primarily in the form of ions such as bicarbonate that cannot diffuse through the gas-permeable membrane. (b) Illumination of the photoacid reduces the pH in the boundary layer on the carbon-containing liquid source side and / or adjacent to the membrane on the carbon-containing liquid source side. (c) The lower pH in this region causes bicarbonate and / or carbonate ions to combine with protons, resulting in the formation of CO2 molecules. (d) The CO2 diffuses through the membrane and is quickly carried away from the membrane region. (e) When illumination is removed, the photoacid is regenerated, forming a basic solution. This basic solution is advected by the fluid stream consisting of the carbon-containing source liquid. (f) A fluid flow consisting of carbon-containing source liquid replaces the dissolved inorganic carbon ions on the source side of the membrane, allowing the process to begin again. The dashed arrows indicate the movement of the fluid or gas flow. The arrows are included in only some of the figures to better illustrate the effect of the flow, but the flow may be continuous. Also, the direction of the fluid and gas flow may be different from the direction of the arrows shown in this figure, the important thing to note here is that the flow carries away material.

[0027] [Figure 11] 11 illustrates a photoacid contained in a secondary fluid separated from the carbon-containing source liquid stream by one or more ion exchange membranes. Protons produced by the photoacid acidify the carbon-containing source fluid, converting some or all of the dissolved inorganic carbon species to CO2. Regeneration of this secondary fluid may be performed using the source fluid after removal of CO2, or regeneration may be performed using other fluids such as natural seawater or natural river water.

[0028] [Figure 12]FIG. 12 illustrates how two processes can be used in series to maximize the efficiency of carbon transfer from a source stream to a target stream: (1) acidifying a carbon-containing source stream with a photoacid to increase the partial pressure of carbon dioxide, and (2) transferring this carbon dioxide to a target stream via a working fluid containing a photoacid.

[0029] [Figure 13] FIG. 13 illustrates an exemplary process for carbon capture using sweep gas, seawater, and photoacid. In FIG. 13, the influent seawater ("SEAW") can be provided by a discharge from a desalination plant or a thermal power plant, or by a current or tidal flow. If the influent seawater flow rate is 36,000 m3 / day of seawater, 1000 tons of CO2 can be produced per year. That is, if the influent seawater flow rate is 36,000,000 m3 / day of seawater, one million tons of CO2 can be produced per year. The amount of seawater required in this example is an estimate, and the exact amount is affected by the efficiency of CO2 removal. For comparison, the amount of seawater pumped and discharged per day at the Dialo Canyon Nuclear Power Plant in California is 8 million m3 / day, and the amount of seawater pumped and discharged per day at the Jubail Seawater Cooling Plant in Saudi Arabia is 30 million m3 / day. As shown in FIG. 13, the process may include a photoacid loop (shown in solid lines), a water flow path (shown in dashed lines), and a gas flow path (shown in dotted lines).

[0030] The photoacid loop may include the following steps: Photoacid (PA) is converted to an acidic state in a photoreaction section. Protons are transferred to seawater through a cation exchange membrane. The photoacid is thermally relaxed to ground state in a dark reservoir. The ground state (base form / high pH) is regenerated by cation exchange from seawater. The cycle can then be repeated.

[0031] The water flow path may include the following steps: Pump seawater through a cation exchange membrane. Acidify the seawater with active PA at the cation exchange membrane. Convert dissolved carbon to CO2. Remove the CO2 with a gas contact membrane. Shift protons from the higher pH seawater back to the ground state PA to regenerate the PA for the next cycle. Draining seawater can reduce the acidity (i.e., increase the pH) of the ocean into which it flows, providing a localized response to ocean acidification.

[0032] The gas flow path may include pumping a sweep gas through a gas contact membrane, adding CO2 from the acidified seawater to the sweep gas at the gas contact membrane, and compressing the CO2 product for transport to a site of sequestration or utilization. Alternatively, a sweep gas may not be used and only a vacuum may be applied to the gas contact.

[0033] [Figure 14]FIG. 14 is a diagram showing an exemplary process for carbon capture using seawater, photoacid, and sweep gas. As shown in FIG. 14, the process may include a photoacid loop (shown in solid lines), a water flow path (shown in dashed lines), a gas flow path (shown in dotted lines), and solar illumination (shown in lightning bolt symbols). In FIG. 14, the parameters for the gas are, for example, a design value for the amount of CO2 captured is 1 kiloton / year. The parameters for the seawater source are, for example, salinity=35, temperature=30° C., alkalinity=2250 μequivalents / kg, total dissolved inorganic carbon (DIC)=2000 μmol / kg, and the inflow seawater flow rate is 36,000 m3 / day. The parameters for the seawater discharged from the process are, for example, total dissolved inorganic carbon (DIC)=1000 μmol / kg. As parameters for the photoacid loop, for example, the average annual solar radiation is set to 6 kW-hours / m2 per day, which is equivalent to the peak solar radiation in San Diego, 17% of the incident sunlight is absorbed by the photoacids, the quantum yield of the photoacid is 0.7 (8.8 moles / m2 of acid is generated per day), the total area of ​​the solar collection area is approximately two American football fields, or about 10,000 m2), the flow rate passing through 1 m2 of the panel at peak light is 5 liters / minute (LPM), the optical depth is 5 mm, the maximum flow velocity of the side solution containing the photoacid is 2 cm / sec, the total flow rate of the side solution containing the photoacid is 40 m3 / min, the total volume of the side solution containing the photoacid is 122 m3, and the total number of moles of photoacid required by the equipment in the process is 600 moles. The parameters for the photoacid are, for example, pKa-Dark=8.3, pKa-light=5.0, the solubility of the ground state protonated form is 3 mM, and the total amount of dissolved photoacid is 5 mM.

[0034] The photoacid loop may include the following steps: converting PA to an acidic state in the photoreaction section; transferring protons to seawater through a cation exchange membrane; thermally relaxing the photoacid to the ground state in a dark reservoir; regenerating the photoacid that has relaxed to the ground state by cation exchange with two seawater sources: acidified seawater that has been discharged from the gas contact section and has had inorganic carbon reduced, and natural seawater. This cycle can then be repeated.

[0035] The water flow path may include the following steps: Seawater is pumped through a cation exchange membrane. Seawater is acidified by active PA at the cation exchange membrane. Dissolved carbon is converted to CO2. The CO2 is removed by a gas contact membrane. Protons are transferred from the higher pH seawater back to the ground state PA, regenerating the PA for the next cycle. Discharging seawater reduces the acidity of the ocean (i.e., increases the pH) into which it flows, providing a localized countermeasure to ocean acidification. Installing this system alongside existing seawater pumping can save energy and reduce costs.

[0036] The gas flow path may include the steps of: pumping the sweep gas through a gas contacting membrane, adding CO2 from the acidified seawater to the sweep gas at the gas contacting membrane, and compressing the gas product with high purity CO2 for transport to a site of sequestration or utilization.

[0037] [Figure 15] FIG. 15 illustrates a photochemical carbon capture stack. An exemplary configuration of the system has a compact form factor achieved as a stack of membranes and chambers, allowing for modular mass production. Similar form factors are employed in fuel cells and membrane desalination. As shown in FIG. 15, the photochemical carbon capture stack includes a photoacid excitation chamber, a first cation exchange membrane (e.g., Nafion), an acidification chamber, a gas contact membrane, a gas flow channel chamber, a support, a seawater effluent chamber, a second cation exchange membrane (e.g., Nafion), and a photoacid regeneration chamber.

[0038] The system can have a similar form factor as a hybrid solar concentrator / thermal collector, and indeed there are use cases where sunlight is used for a process and other parts of the solar spectrum are also used for solar power generation.

[0039] [Figure 16]FIG. 16 illustrates an exemplary system 1600 for removing carbon from a carbon-containing liquid. The system includes a first duct 1602, a second duct 1604, an nth duct 1606, a stimulator 1608, a flow device 1610, one or more membranes 1612, a heat source 1614, and a computer system 1616. The first duct 1602, the second duct 1604, and the nth duct 1606 are configured to transport the carbon-containing liquid, the secondary fluid, and / or the target stream. The stimulator 1608 is configured to activate the photoactive compound. The stimulator may include a light source. The flow device 1610 is configured to move the carbon-containing liquid to cause it to flow. The membrane 1612 is configured to allow the transfer of carbon from one environment to another. The heat source 1614 is configured to heat the carbon-containing liquid. The computer system 1616 includes a processor 1618, a communication unit 1620, an input / output (I / O) unit 1622, and a memory 1624. The memory 1624 may be a computer readable storage medium having computer executable instructions stored therein. The memory may include the following components: The exposure unit 1626 is configured to expose the carbon-containing liquid in the first duct to the photoactive compound, thereby lowering the pH of the carbon-containing liquid. In some embodiments, the exposure unit 1626 may be configured to expose the carbon-containing liquid to the membrane 1612 when the secondary fluid is at a higher pH state for a sufficient time for carbon to be removed from the carbon-containing liquid and transferred to the secondary fluid. The carbon removal unit 1628 is configured to remove carbon from the carbon-containing liquid and transfer it to the second environment. The flow unit 1630 is configured to control the flow of the carbon-containing liquid using the flow device 1610. The activation unit 1632 is configured to activate the photoactive compound using the stimulation unit 1608. The deactivation unit 1634 is configured to deactivate the photoactive compound by removing the photoactive compound from the stimulation unit 1608. The carbon recovery unit 1636 is configured to recover the removed and migrated carbon. Recovery of the removed carbon occurs after deactivation of the photoactive compound. The heating unit is configured to heat the carbon-containing liquid using the heat source 1614.For example, the system 1600 may be configured to communicate with a remote computing device 1640 via a network 1642 .

[0040] [Figure 17] FIG. 17 illustrates how seawater and sunlight can be used as part of an energy-efficient method to produce CO2 for further use or sequestration. The carbon capture process takes advantage of the high concentration of dissolved carbon (DIC) in seawater. This DIC is converted to CO2 by light-activated photoacids, which then diffuse through a gas contact membrane. The CO2 product can be used as is, or pressurized and purified to the levels required for various markets, such as sequestration, fertilizer, plastics, cement, methanol, or biofuel production. The energy and cost expenditures associated with pumping can be further reduced by collocating with facilities such as power plants or desalination plants that pump large amounts of seawater, or by using tidal or river currents to provide the necessary head pressure, and the wastewater stream can be converted into a green revenue stream.

[0041] [Figure 18]FIG. 18 illustrates the photoacid cycle. A light-induced reaction can transfer alkalinity from the inflow seawater to the outflow seawater. During this time, the seawater is temporarily acidified, which releases CO2. The graph shows the photoacid pH during the repetition of the disclosed process and is based on modeling using the properties of a recently reported photoacid with pKa-Dark=7.33 (Wimberger et al., Basic-to-acidic reversible pH switching with a merocyanine photoacid. Chemical Communications, 2022, 58(37), 5610-5613). The model was validated against published reports of photoacids and shows that existing photoacids such as this one can be used as part of the carbon removal cycle. The shape and position of the cycle can be optimized and are influenced by the amount of strong base or strong acid originally added to the photoacid solution. In this example, the pH plotted is the pH of the by-fluid containing the photoacid.

[0042] [Figure 19] FIG. 19 is an exemplary overall process diagram of a system of the present disclosure for capturing CO2 from seawater or other natural water or industrial wastewater streams.

[0043] [Figure 20] Figure 20 shows an exemplary modular carbon collector with solution, gas, ion exchange membrane, and gas contact membrane layers. Dimensions and fluid flow rates shown are per square meter of modular carbon collector surface area.

[0044] [Figure 21] Figure 21 illustrates an example of a carbon capture system of the present disclosure that removes CO2 from source water in a series of carbon capture vessels as shown in Figure 20. The top left diagram illustrates the transfer of acidified seawater to a centralized gas transfer facility where carbon removal occurs. The top right and bottom diagrams illustrate an example of a photoacid recycle technique that reduces the number of pumps required.

[0045] [Figure 22] FIG. 22 illustrates an example of a carbon capture system incorporating photovoltaic (PV) cells that can generate electricity using more than 80% of the incident sunlight without the need for reversible photoacid (RPA) activation. This configuration is similar to commercially available hybrid solar / thermal (PVT) panels used to simultaneously generate electricity and hot water, but is unique to this disclosure. The left side of FIG. 22 illustrates the energy balance of a hybrid carbon capture and photovoltaic (PV) system. Sunlight activates the photoacid and heats the water beneath a transparent cover layer. The light penetrates the water and photoacid and is incident on the PV panel beneath the water. The generated heat is used to increase the temperature of the carbon-containing fluid, raising its partial CO2 pressure (pCO2). An example of a modular design form factor for this system, similar to commercially available PVT panels, is shown on the right side of FIG. 22. A schematic of the fluid layers and flow paths, along with the membrane and PV layers, is shown in FIG. 22 (continued) on a separate page.

[0046] [Figure 23] Carbon flux versus vacuum (x-axis), ocean flow rate (plot caption), and ocean temperature (shades of grey). These results are from experiments using slightly acidic water with a CO2 partial pressure of 800 ppm.

[0047] [Figure 24] FIG. 24 shows that the decomposition products of the hydrolysis of merocyanine photoacids, such as photoacids that can be used in the present process, can be the reaction products of the final step of the synthesis of photoacids. This allows the hydrolysis products to be recovered from the photoacid solution after multiple cycles in the present process and reacted to regenerate the photoacid, reducing the cost of producing the photoacids of the present disclosure. This is adapted from Berton et al., (2020) Chem. Sci. 11(32): 8457-8468.

[0048] [Diagram 25]Figure 25 shows the relative abundance of dissolved inorganic carbon species in a typical seawater as a function of pH. The thick black line shows the relative abundance of dissolved CO2*. This carbon species is a minor component of dissolved inorganic carbon at seawater pHs above the pKa of carbonic acid, which is 6 in seawater and depends on temperature, pressure, and other solution properties. Above this pH level, other species of dissolved inorganic carbon, HCO3- (dashed grey line) and CO3 2- (dotted grey line), become more abundant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] The disclosed systems and methods are configured to remove dissolved inorganic carbon from a carbon-containing liquid and transfer the carbon from the source stream to a second environment, which may be another liquid or gas and is referred to herein as the target stream. The removal results in transfer to the target stream. The concentration of dissolved inorganic carbon in water, i.e., dissolved carbon dioxide, can be CO2, carbonate (H2CO3), bicarbonate (HCO3), or nitrate (NNO3), depending on the pH of the water body. - ), carbonate (CO3 2- The total amount of dissolved CO2 makes up the dissolved inorganic carbon concentration in water (Dodds, et al., Freshwater Ecology, 2002).

[0050] In one example of this process (left side of FIG. 5), CO2 is first removed from a source stream through a membrane and transferred to a working fluid. The working fluid includes one or more photoactive compounds. The process can be carried out, for example, using a reversible photoacid or a metastable photoacid. In some embodiments, the photoactive compound is used to shift the pH of the working fluid between a higher pH state and a lower pH state as a result of light stimulation.

[0051] As part of the process contemplated (FIG. 5), diffusion of CO2 from the source stream into the working fluid occurs when the working fluid is at the higher pH state. After sufficient time has passed to remove CO2 from the source stream, the working fluid is functionally separated from the source stream by sealing or impermeating the membrane or gas contact and / or separating the working stream from the membrane. The amount of time required for CO2 removal is in accordance with known chemical principles. Factors related to this amount of time include the diffusivity of the membrane, the flow rate of the source stream, the flow rate of the working fluid, the volume of the membrane shell and core, the temperature of the source stream, and the concentration gradient of inorganic carbon species across the membrane. In one embodiment, separation is achieved by pumping the working fluid as part of a continuous flow system. When not in contact with the membrane, the working fluid is isolated from other fluids and gases to limit carbon exchange. Other functional separations are possible.

[0052] The working fluid can then be shifted to a lower pH state by the photoactive compound stimulated by light. For other types of photoactive compounds whose more stable form is acidic, this shift occurs by the acid spontaneously returning to the lower pH state over time when unstimulated. The shift to a lower pH state increases the concentration of carbonate and the partial pressure of carbon dioxide in the working fluid. In this lower pH state, the working fluid is allowed to interact with the target stream through the membrane or gas contact. Due to the higher concentration of carbonate and the higher partial pressure of carbon dioxide, inorganic carbon diffuses through the membrane or gas contact into the target stream. After a sufficient time for carbon to migrate into the target stream, the working fluid is functionally separated from the target stream. This separation may be achieved by sealing or making the membrane or gas contact impermeable and / or by separating the working stream from the membrane. This separates the working stream from interaction with the target stream. The amount of time required for carbon to migrate is in accordance with known chemical principles. Factors that influence this amount of time include the diffusivity of the membrane, the flow rate of the target stream, the temperature of the target stream, the flow rate of the working fluid, the volume of the shell and core portions of the membrane, and the partial pressure gradient of carbon dioxide across the membrane.

[0053] The working fluid then returns to the higher pH state, either by spontaneous conversion of photoactive compounds that spontaneously return to the higher pH state over time in the unstimulated state, or by stimulation with light for other photoacids whose more stable forms are acidic. The shift to the higher pH state reduces the concentration of carbonic acid and the partial pressure of carbon dioxide in the working fluid. The regenerated working fluid is again subjected to chemical interaction with the source stream via a membrane or gas contact. Carbon diffuses into the working fluid, and the process repeats.

[0054] In the single stage process, the same working fluid interacts with both the source and target streams. A multi-stage process is envisioned in Figure 6. In each stage, CO2 transfers through a membrane from one working fluid at a higher pH state to the other at a lower pH state. Each working fluid cycles between lower and higher pH states as described above. By employing multiple stages, the concentration of inorganic carbon in the final target stream can be increased to meet a wide range of application needs.

[0055] Another version of the process (FIG. 7) is configured to remove CO2 from the source stream by acidifying the source stream and converting all or a portion of the dissolved inorganic carbon species to CO2. Many embodiments of this version of the process remove CO2 directly from the source stream, for example via a membrane, and transfer the CO2 to a target stream (e.g., a target liquid or target gas). As part of this process, the source fluid is shifted to a lower pH state by the action of a photoactive compound, thereby converting all or a portion of the dissolved inorganic carbon species (H2CO3, HCO3 - , CO3 2- ) is converted to CO2, i.e., converted to a form that can be removed from the source stream and transported to the target fluid, e.g., via a membrane or gas contact. The process may be performed, for example, with a reversible or metastable photoacid added directly to the source stream. Such processes may be performed on a small scale (e.g., mL to L), e.g., for laboratory analysis of dissolved inorganic carbon concentration and isotopic composition, or on a large scale, e.g., for extraction of CO2 from seawater or other carbon-containing fluids.

[0056] In some examples (FIGS. 7-10 and 12), the photoactive compound is disposed directly within the carbon-containing source stream itself (e.g., (Chandra, A., et al. (2021). "Highly Sensitive Fluorescent pH Microsensors Based on the Ratiometric Dye Pyranine Immobilized on Silica Microparticles." Chemistry -A European Journal 27(53): 13318-13324), fixed at a boundary adjacent to a carbon-containing source stream, embedded in a body adjacent to a carbon-containing source stream, disposed within a secondary fluid, or any combination of these approaches. Stimulating the photoactive compound with light causes the photoactive compound to become more acidic, which shifts the pH of the source fluid below the initial pH of the source fluid, as long as the pKa of the photoactive compound in the stimulated state is low. For other types of photoactive compounds that are in a more basic form when illuminated, this shift occurs due to the photoactive compound spontaneously reverting back to a more acidic state over time in the absence of stimulation. By shifting the source fluid to a lower pH state, the photoactive compound can be stimulated to become more acidic. The shift in pH to 0.5 increases the carbonate concentration in the source fluid, increasing the partial pressure of carbon dioxide. During this lower pH state, the source fluid is allowed to interact with the target stream, allowing carbon dioxide to diffuse through, for example, a membrane or gas contact. Optionally, the carbon exchange can be configured without a membrane or gas contact, in which case carbon is removed and transferred directly from the source liquid to the target gas stream. The amount of time required for sufficient carbon transfer between the acidified source fluid and the target stream is governed by known chemical principles. Factors related to this amount of time include the diffusivity of the membrane, the flow rate of the source stream, the flow rate of the target stream, the properties of the membrane, if present, the temperature of the process stream, and the concentration gradient of the inorganic carbon species between the streams.

[0057] After the photoactive compound has had sufficient time to acidify the source stream, the photoactive compound is functionally isolated from the portion of the process where carbon dioxide exchange is occurring. This can be accomplished, for example, by physically removing or replacing the portion carrying the photoactive compound, and / or by covering or impermeating a membrane or gas contact, and / or by redirecting the flow of the source stream so that it does not interact with the photoactive compound upstream of the carbon transfer process, or any combination of these processes. The ability of the photoactive compound to acidify the source stream follows known chemical principles. Key factors related to this ability include the amount of photoactive compound, the amount of photoactive compound that can be converted to a more acidic state by exposure to a stimulus or source fluid, and the flow rate of the source stream. Functional isolation is maintained until the photoactive compound is converted back to a more basic state, a step referred to as "regeneration" in the present process. As used herein, "relaxation" or "deactivation" refers to the spontaneous reversion of the photoacid to a less acidic form in the absence of light, and "regeneration" refers to allowing the photoacid to relax before diffusing protons into the photoacid solution, allowing the process to function as a continuous cycle. Regeneration occurs when the photoactive compound is removed from under the stimulus and reverts to a more basic state, and is exposed to a liquid with a low pH relative to the pKa of this more basic state. After regeneration, the photoactive compound is functionally returned to the portion of the process where carbon dioxide exchange occurs. The entire cycle is repeated to remove further carbon.

[0058] There are many configurations that allow for the acidification of source water using photoactive compounds, followed by separation of the photoactive compounds from the location where the carbon transfer occurs, and regeneration of the photoactive compounds. In one embodiment (FIG. 8), the acidification step of the source fluid is accomplished as part of the flow through the system when the source fluid is pumped through a batch of photoactive compounds under irradiation upstream of a membrane or gas contact. The batch may consist of photoacid immobilized on a substrate. This batch is designated as batch A. The source fluid flowing through batch A is acidified, and the carbon is then transferred to the target stream through a membrane or gas contact (top of FIG. 8). After transferring the carbon, the source fluid is passed through a batch of photoactive compounds under unstimulated conditions. This batch is designated as batch B. Batch B of photoactive compounds is regenerated by the source fluid that has passed through the carbon exchange zone. After the capacity of batch A to acidify the source water is reached and batch B is regenerated, the direction of the flow of the source fluid is reversed, stimulation of batch A is stopped, and stimulation of batch B is performed (bottom of FIG. 8). In this new flow direction, batch B provides acidification of the source fluid and batch A is regenerated. The process can switch between these two configurations multiple times to allow for near-continuous transfer of carbon from the source fluid to the target stream. In other configurations, the flow direction of the source fluid is not reversed, but the source water is configured to flow through separate batches of photoactive compound that are irradiated or regenerated at separate times. In other configurations, the photoactive compound is regenerated using a source fluid from another step of the process. In other configurations, the regeneration of the photoactive compound is performed using a fluid that is not the source fluid.

[0059] In other configurations, the photoactive compound (photoacid) is immobilized on the source fluid side of the membrane or embedded within the membrane (FIGS. 9 and 10). In some embodiments, the addition of the photoactive compound to a CO2 permeable membrane material such as polyacrylonitrile can be accomplished via a sonication process. Irradiation of the source fluid side of the membrane activates the photoacid to a low pH state, which promotes the production of carbonic acid and carbon dioxide from bicarbonate and carbonate ions in the source fluid, increasing the partial pressure of carbon dioxide at the membrane interface and increasing the carbon dioxide gradient between the source and target streams. In one configuration, regeneration of the stimulated state photoacid embedded or bound to the membrane can be accomplished by flowing a water source stream in the absence of illumination. In other configurations, the rapidly regenerating photoacid can be configured to remain under continuous illumination if the time scale at which CO2 is removed through the membrane is faster than the time scale at which the photoacid relaxes from the stimulated state.

[0060] In another configuration, the photoacid can be contained in a side solution separated from the source fluid by one or more ion exchange membranes through which protons can diffuse into the source fluid, as shown in FIG. 11. In this configuration, the side solution is irradiated to shift the photoacid to a more acidic state, thereby generating protons, which are then transferred to the source fluid, for example, by diffusion through the membrane. In one example of some configurations that can maintain charge balance during proton diffusion, this diffusion is accompanied by cation diffusion moving in the opposite direction. Other examples include using other fluids to replace cations in the side fluid, or removing anions in the side fluid. Alternatively, these anions or cations can be generated via an electrochemical process. The side fluid is then functionally isolated from the part of the process in which proton diffusion occurs. The side fluid is then removed from irradiation and placed in functional contact with the other fluid stream, for example, via an ion exchange membrane, so that the side fluid returns to a more basic state. This fluid may be the source fluid after carbon removal, or another unaltered source fluid, or another fluid with a pH lower than the pKa of the photoacid in its basic form, which serves as a proton source. The photoacid is regenerated as protons diffuse into the secondary fluid. One example of some configurations that may maintain charge balance during proton diffusion is one in which this diffusion is accompanied by cation diffusion moving in the opposite direction. Other configurations include using another fluid to replace cations in the secondary fluid or to remove anions in the secondary fluid. Alternatively, these anions or cations may be generated via an electrochemical process.

[0061] In another version of this process, CO2 is first removed from the source stream through a membrane and transferred to a working fluid (FIGS. 5 and 6). As part of this process, the source stream is shifted to a lower pH state through the action of a photoacid, as previously described, thereby transferring CO2 from the source stream to the working fluid, which contains the photoactive compound. This working fluid is then used to transfer carbon directly to a target stream, or it can be used to transfer carbon to another batch of working fluid as part of a multi-step process.

[0062] Another version of the above process uses temperature change with pH change to control the flow of inorganic carbon. Increasing the temperature of the solution decreases the solubility of dissolved CO2 and increases the partial pressure of CO2. Heating the carbon-containing source stream to release dissolved carbon may occur before, after, or during exposure of the carbon-containing source stream to the activated photoacid. Conversely, decreasing the temperature of the solution increases the CO2 solubility and decreases the partial pressure of CO2. In other words, increasing the temperature is the same as decreasing the pH of the carbon-containing solution, but the temperature change configuration does not require a photoacid. A disadvantage of using the temperature of the fluid itself instead of using pH or photoacid is that fluids such as seawater and other natural waters have a large heat capacity and a correspondingly large amount of heat must be transferred into or out of the source fluid and / or working fluid to sufficiently shift the solubility of carbon. Temperature-based configurations may be advantageous in configurations where there is an existing abundant source of heat or cold, such as as part of a water-cooled power plant.

[0063] Another combination of systems and methods that combines the above approaches to utilize heating, cooling, and pH changes in source liquids and / or working fluids to recover carbon is shown in one embodiment in FIG.

[0064] The use of reversible photoactive compounds has traditionally been employed to concentrate CO2, particularly from gas streams, but not from liquids such as seawater. The innovation described in this disclosure takes advantage of the natural concentration of inorganic carbon in liquids such as seawater, but not from air. For example, a typical ocean surface seawater contains about 140 times more inorganic carbon than the same volume of air. By using seawater or other liquids rich in inorganic carbon as a carbon source, an otherwise inefficient approach can be transformed into a useful carbon capture strategy. Although the configuration of seawater and other liquids as inorganic carbon sources for carbon capture shows promise and is an active area of ​​research, the current commercialization of carbon capture technologies is limited. The process described herein combines the use of liquids such as seawater to preconcentrate inorganic carbon with methods to transport and concentrate this carbon.

[0065] As described in more detail below, the resulting CO2-enriched target stream can be used in a variety of processes or stored.

[0066] Examples of liquids for use as source streams or carbon-containing liquids include, but are not limited to, tap water, river water, sea water, lake water, glacial water, ocean water, saline water, natural water, estuary water, strait water, canal water, gulf water, estuary water, polynya water, bay water, inlet water, shallow water, ice water, acidic water, basic water, industrial water, water involved in power plants or industrial cooling, water involved in desalination, water involved in industrial processes, and / or storm water.

[0067] There are a variety of components / components and parameters involved in performing carbon removal or pre-concentration from a source liquid, including the carbon species to be recovered, the liquid solution containing the carbon species, the source liquid stream, the membrane or gas contact, the working fluid containing the photoactive compound, the side fluid containing the photoactive compound, pre-acidification of the source stream with a photoacid to convert bicarbonate and carbonate to dissolved CO2, and the target stream.

[0068] Recovery of carbon from a source liquid involves separating the produced or released carbon from the source liquid.

[0069] The disclosed systems and methods can use aqueous or non-aqueous solutions or mixtures as the working fluid and / or any secondary fluid. Advantages of aqueous solutions include simplicity, compatibility with a wide range of membrane and gas contactor materials, and ease of use. Advantages of non-aqueous solutions include higher solubility of the photoacid and longer lasting stability of the photoacid, which may increase process efficiency and reduce process costs. Examples of non-aqueous solvents include protic solvents (ammonia, ethanol, methanol, etc.), aprotic solvents (acetonitrile, acetone, dimethylsulfoxide, etc.), etc.

[0070] As described herein, the working fluid contains a photoactive compound and attracts and transfers carbon from the carbon-containing liquid to itself. Systems using the working fluid are shown, for example, in Figures 7 and 8. The secondary fluid contains a photoactive compound and provides acidity to the carbon-containing liquid, but is not designed to attract and transfer carbon to itself; thus, the secondary fluid is not directly part of the carbon removal and transfer pathway. Systems using the secondary fluid are shown, for example, in Figures 13, 14, and 15, as well as Figures 19, 20, and 22.

[0071] In the context of this disclosure, "membrane" refers to a material that separates a liquid from another liquid or gas but allows for (1) the diffusion of CO2 and / or H2CO3 or other gases, or (2) the diffusion of certain ions between the liquids. "Gas interface" refers to a material that separates a certain liquid from a gas or liquid but allows for the diffusion of CO2 and / or H2CO3. Such materials are well known to those skilled in the art. Examples include hollow fiber gas interface with polymeric, wooden, or ceramic fibers. An example of a commercially available product is manufactured by 3M under the trade name Liqui-Cel. An example of a polymeric membrane material for the gas interface is polydimethylsiloxane (PDMS) or poly-4-methyl-pentene-1 (PMP), and an example of a commercially available non-porous membrane unit is the SEPAREL product series from DIC Corporation. "Ion exchange membrane" refers to a material that separates one liquid from another but allows for the diffusion of certain ions between the liquids. An example of a commercially available ion exchange membrane is Nafion manufactured by Chemours.

[0072] In some embodiments, seawater is the source stream and air is the target stream. The system may be comprised of a commercially available membrane unit, such as the SEPAREL product series (DIC Corporation), and any number of commercially available pumps, such as a centrifugal pump. Illumination may be achieved using light emitting diodes, such as fiber-coupled LEDs from Prismatics, Inc., or other light sources. The synthesis of photoacids may be carried out by a method that has been published, for example, in "Berton et al., "Thermodynamics and kinetics of protonated merocyanine photoacids in water" Chemical Science, 11(32), pp.8457-8468," "Shi et al., "Long-lived photoacid based upon a photochromic reaction." J. Am. Chem.Soc. 2011,133, 14699-14703," "Zayas et al., "Tuning Merocyanine Photoacid Structure to Enhance Solubility and Temporal Control: Application in Ring Opening Polymerization." ChemPhotoChem 2019,3, 467-472," or "Wimberger, Laura, Joakim Andréasson, and Jonathon E. Beves. "Basic-to-acidic reversible pH switching with a merocyanine photoacid." Chemical Communications 58, No. 37 (2022): 5610-5613." The photoacid synthesis method may also be used.To assess the effectiveness of this process, the carbon transport rate and carbon gain in the target stream can be monitored by performing a coulometric total dissolved inorganic carbon analysis as described in Dickson, Sabine, and Christian (Eds.) 2007. “Guide to Best Practices for Ocean CO2 Measurements” PICES Special Publication 3, and by measuring the partial pressure of carbon dioxide in the target stream using an instrument such as a Li-Cor CO2 Analyzer (Li-Cor Biosciences).

[0073] Aspects of the disclosure relating to (i) pH and carbon diffusion, (ii) photoactive compounds, and (iii) the use and location of the carbon removal system are described below with further details and optional configurations. These headings are for explanatory purposes only and are not intended to limit the scope or interpretation of the disclosure. Further examples, modeling, and experimental data are described in detail in Example 1.

[0074] (i) pH and carbon diffusion The main factor that determines whether carbon will diffuse from one stream to another through the membrane or gas interface is the difference in the partial pressure of carbon dioxide (pCO2) between both streams. The two streams may both be fluids or may be a fluid and a gas. The first stream may be a source stream and the second stream a working fluid. Alternatively, the first stream may be a working fluid and the second stream a target stream. The first stream may be a sample of one working fluid at a low pH condition and the second stream a sample of the other working fluid at a high pH condition. In the fluids, the partial pressure of carbon dioxide is: pCO2=x0×DIC×K H '

[0075] where pCO2 is the partial pressure of carbon dioxide in the fluid. DIC is the concentration of total dissolved inorganic carbon in the fluid, and its formula is DIC = [CO2 * ]+[HCO3 - ]+[CO3 2-] where [CO2 * ] is the uncharged aqueous species CO 2(aq) and H2CO3, the formula is [CO2 * ] = [CO 2(aq) ] + [H2CO3]. 2(aq) In hydrospheric chemistry, CO2 is usually used because distinguishing it from H2CO3 requires difficult experiments that are usually not practical. * The concept of x0 is the mole fraction of dissolved carbon dioxide relative to total dissolved carbon (CO2 * ), the formula of which is: x0 = [CO2 * ] / ([CO2 * ]+[HCO3 - ]+[CO3 2- ]) = [CO2 * ] / DIC. H ' is the apparent Henry's law gas constant for a particular fluid state and is a function of temperature, pressure, ionic strength, major ionic fluid constituents, and the type of fluid or solvent used.

[0076] The relative abundance of dissolved carbon dioxide to total dissolved carbon (x0) is a function of pH (see Figure 25), which is important for the functioning of this process. x0 = [H + ] 2 / ([H + ] 2 + [H + ]K1 ’ + K1'*K2') and [H + ] = 10 -(pH) K1' and K2' are the first and second apparent dissociation constants of carbonic acid corresponding to the particular temperature, pressure, ionic strength, and major ion concentration of a particular fluid.

[0077] According to the above relationship, which is described in the literature in the field of hydrochemistry (see, for example, Stumm and Morgan. Aquatic Chemistry -3rd ed. John Wiley & Sons Inc. (1996)), lowering the pH increases the molar fraction of dissolved carbon dioxide relative to total dissolved carbon, which tends to increase the partial pressure of carbon dioxide. Conversely, increasing the pH decreases the molar fraction of dissolved carbon dioxide relative to total dissolved carbon, which tends to decrease the partial pressure of carbon dioxide.

[0078] The use of a photoacid to lower the pH of a source stream increases the partial pressure of carbon dioxide in the source stream, and the photoacid may be (1) located within the source stream itself (e.g., embedded in a water-contacting solid particle or surface), (2) located on or in a gas-permeable or gas-contacting membrane that separates the source stream from the target stream, or (3) located in a secondary fluid that is separated from the carbon-containing source stream by one or more ion-exchange membranes that allow the permeation of protons from the photoacid solution into the source stream.

[0079] In the configurations shown in Figures 5 and 6, the pH of the working fluid in contact with the source stream is high enough that the partial pressure of carbon dioxide in the working fluid is lower than the partial pressure of carbon dioxide in the source stream. This causes carbon dioxide to diffuse from the source stream into the working fluid. After the photoactive compound changes form, thereby lowering the pH of the working fluid, the new pH is low enough that the partial pressure of carbon dioxide in the working fluid is higher than the partial pressure of carbon dioxide in the target stream. This gradient in partial pressure of carbon dioxide causes carbon to diffuse from the working fluid into the target stream.

[0080] (ii) Photoactive Compound In certain embodiments, the term "light" refers to actinic light, including any light capable of producing a photochemical reaction.

[0081] In certain embodiments, the term "photoactive" as used herein with respect to compounds and molecules refers to a compound that can respond to light by a chemical reaction, such as a structural change.

[0082] In certain embodiments, the term "photoacid," as used herein with respect to a compound, refers to a compound that can be converted from a base or a relatively weak acid to a relatively strong acid by a photochemical reaction.

[0083] Irradiation of the photoactive compound with light causes the photoactive compound to convert from at least one of a first state or a second state to the other of the first state or the second state. For example, if the photoactive compound is in a first state, upon exposure to light, the photoactive compound changes from the first state to a second state. In this case, the first state of the photoactive molecule is a ground state, and the second state of the photoactive molecule is an excited state. Alternatively, if the photoactive compound is in a second state, upon exposure to light, the photoactive compound changes to the first state. In this case, the second state of the photoactive molecule is a ground state, and the first state of the photoactive molecule is an excited state.

[0084] In one embodiment, the photoactive compound is sensitive to light of a specific wavelength. The photoinduced structural change between the required states is achieved by exposure to or removal of light of a specific wavelength corresponding to the absorption band of the photoactive molecule. In some examples, the photoactive compound is sensitive to both UV and visible light.

[0085] Alternatively, the photoactive compound may be sensitive to visible light only. In yet another alternative embodiment, the photoactive compound is sensitive to UV light. The use of multiple photoactive compounds sensitive to different wavelengths of light may be particularly advantageous when the solution of photoactive compounds contains multiple different types of photoactive compounds. Different types of photoactive compounds may be provided to allow state conversion to occur at different wavelengths in order to increase the spectrum of light that irradiates the photoacid and converts it to excited states of photoacid and protons. This may allow for more efficient use of available light and may reduce capital costs by requiring smaller light collection areas.

[0086] In some embodiments, the light-induced change alters the chemical environment of the photoactive compound. This change may be an electronic or conformational change. The light-induced change may alter the pH of the solution or the pKa of the photoactive compound.

[0087] In one group of embodiments, the photoactive compound is a photoacid. In some examples, the photoacid compounds useful in the present disclosure exist in an acid form (i.e., a protonated form) in the ground state and can be transformed into an excited state upon irradiation with light. The excited state is typically the conjugate base of the photoacid and may exist in a deprotonated form. Protonation by the ground state form and transformation to the excited state form upon irradiation reduces the pH of the surrounding solution.

[0088] The working range of a photoactive compound can be related to the pKa difference between the excited state and the ground state of the photoactive molecule. The working range can be confirmed by measuring the pKa of the photoactive compound in the ground state (e.g., in the form of a base or a relatively weak acid) and the pKa of the photoactive compound in the excited state (e.g., in the form of a relatively strong acid). Thus, the pKa difference between these two forms can define the working range of a photoactive compound.

[0089] In one embodiment, the working range of the sub-solution, including photoacid and other acids or bases, is utilized to shift or adjust the working range of the sub-solution.

[0090] In one embodiment, the excited state form of the photoactive compound has a lower pKa than the ground state form of the photoactive compound.

[0091] In another embodiment, the excited state form of the photoactive compound has a higher pKa than the ground state form of the photoactive compound.

[0092] In some embodiments, the pH of the source solution is within the pKa working range of the photoactive compound, and excitation of the photoactive compound causes a decrease in pH.

[0093] In some embodiments, when the photoactive compound is in its ground state, a first state, the solution has a higher pH, and upon exposure to light, the photoactive compound is converted to a second state in which the solution has a lower pH. In some embodiments, when the photoactive compound is in its ground state, a first state, the solution is alkaline or slightly acidic, and upon exposure to light, the photoactive compound is converted to a second state in which the solution is acidic. In one group of embodiments, photoexcitation of the photoactive molecule leads to a decrease in the pH of the surrounding solution. In some embodiments, when the photoactive compound is in the first state, the pH of the solution is 7-10, or 9-12, and when the photoactive compound is in the second state, the pH of the solution is 2-7.5, or 0-8.

[0094] In some embodiments, the change in pKa upon excitation of the photoactive compound is at least 0.5, at least 1.0, at least 2.0, or at least 3.0. In some embodiments, the light-induced change is a change in the acid or base dissociation constant of a functional group.

[0095] In one group of embodiments, the light energy applied to the solution is sufficient to cause a light-induced change in the photoactive compound, but not sufficient to heat the working solution.

[0096] In some embodiments, the photoactive compound is present in the working solution at a concentration ranging from 0.1 mol / L to 50 mol / L, from 0.01 mmol / L to 0.1 mol / L, or from 0.1 mmol / L to 10 mol / L. In some embodiments, the photoactive compound is present in the working solution at a concentration ranging from 1 mol / L to 10 mol / L. In some embodiments, the photoactive compound is present in the solution at a concentration ranging from 3 mol / L to 7 mol / L. The concentration range may be from any of the lower concentration limits to any of the upper concentration limits. The concentration of the photoactive compound may vary depending on the presence of other compounds in the solution. In the presence of other absorbing molecules such as amines, configurations with lower concentrations of the photoactive compound may be employed.

[0097] In some embodiments, the photoacid is embedded in a solid particle or membrane and the carbon-containing fluid is configured to pass through or within the solid particle or membrane to lower the pH and increase the pCO2 of the source stream.

[0098] In another group of embodiments, the photoacid is disposed in a secondary fluid separated from the carbon-containing source stream by an ion exchange membrane that can pass protons to the source stream or accumulate protons on its surface facing the source stream, thereby lowering the pH and increasing the pCO2 of the source stream adjacent the ion exchange membrane.

[0099] In one group of embodiments, the change in pH may be influenced by the concentration of the photoactive compound in the solution, and in some cases, increasing the concentration of the photoactive compound may allow for greater changes in pH.

[0100] Some general classes of photoactive compounds can be illustrated with reference to the following non-limiting examples, which illustrate the transformations that occur upon irradiation with light. Fulgides [ka] Diarylethenes [ka] Azobenzenes [ka] Spiropyrans and merocyanines [ka] Spirooxazines and merocyanines [ka] Quinones [ka] In the formula, a)X = O, R 1 = Ph, b) X = CR 2 R 3 , R 1 = H, c) X = O, [ka] In the formula, R 2 and R 3 is hydrogen or an alkyl group, R 4 is an alkyl group. Triphenylmethanes [ka] Tricyanofurans [ka]

[0101] In the above examples of spiropyrans, merocyanines, and spirooxazines, the substituent "R" can be, for example, hydrogen, C1-C6 alkyl groups, and a-(CH2) nand W, wherein n is 1 to 6 (eg, 2 to 4), and W is -NH2, CO2-, or SO3- (eg, SO3-).

[0102] In the above examples of spiropyrans and merocyanines, the functional group -NO2 on the ring may be absent, may be in another position, or may be replaced by another functional group.

[0103] In the above examples of spiropyrans, merocyanines, and spirooxazines, functional groups such as -OCH3 may be added or other functional groups may be replaced with functional groups such as -OCH3.

[0104] In some embodiments, the one or more photoactive compounds are selected from the group consisting of leucoxides, perimidine spirocyclohexadienones, azobenzenes, spiropyrans, spirooxazines, dithienylethenes, fulgides, quinones, benzopyrans, naphthopyrans, and dihydroindolizines. In some embodiments, the one or more photoactive compounds are selected from the group consisting of spiropyrans, merocyanines, and naphthols (e.g., 1-(2-nitroethyl)-2-naphthol).

[0105] In embodiments, reversible photoacids include fulgides, diarylethenes, azobenzenes, merocyanines, spiropyrans, spirooxazines, quinones, and the like.

[0106] In an embodiment, the photoactive compound is a metastable photoacid, such as a photoacid that undergoes a conformational or structural change upon exposure to light, changing its acidic or basic properties. Examples of such compounds are given in paragraph

[0100] , and the synthetic routes to all of the exemplified compounds are publicly available.

[0107] In certain embodiments, merocyanines are preferred photoacids due to their long active-state lifetime (typically minutes), high achievable pKa values ​​in the dark (which define the available range of pH values ​​of natural waters that can be used), relatively high water solubility, and relatively high stability against hydrolysis and photolysis. In certain embodiments, merocyanines with methoxy substituents on the indolinium ring and butylsulfonic acid groups on the nitrogen atom of the indolinium, as reported by Wimberger et al. (Basic-to-acidic reversible pH switching with a merocyanine photoacid. Chemical Communications, 2022, 58(37) 5610-5613), are preferred. In certain embodiments, the preferred photoacid is as follows: [ka] The structure on the left is the deactivated (ground) form (an example of a merocyanine) and the structure on the right is the activated (excited) form (an example of a spiropyran). The structure of this compound could be modified to further improve its pKa in the dark, its hydrolytic stability, and its water solubility.

[0108] Figure 3 shows a useful merocyanine-spiropyran pair that is activated by visible light (but not UV) and relaxes spontaneously (e.g., upon heating).

[0109] Other examples of photoacid compounds suitable for use include those known in the art, and examples of such compounds are described in the following references: Berton et al., Thermodynamics and kinetics of protonated merocyanine photoacids in water. Chemical Science, 2020, 11(32), pp.8457-8468; Shi et al., Long-lived photoacid based upon a photochromic reaction. J. Am. Chem.Soc. 2011,133, 14699-14703; Zayas et al., Tuning Merocyanine Photoacid Structure to Enhance Solubility and Temporal Control: Application in Ring Opening Polymerization. ChemPhotoChem 2019,3, 467-472.; Berkovic et al., Chem. Rev. 2000., 100, 1741-1754; Metsuda et al., J. Photochem. Photobiol., C2004, 5169-182; Yokoyama Chem. Rev. 2000, 100, 1717-1740; US Patent No. 4,636,561; US ​​Patent No. 6,549,327; US Patent No. 5,879,592; US Patent No. 5,185,390; US Patent No. 6,211,374; European Patent No. EP0277639; Chen et al., Photochem. Photobiol. Sci., 2011, Jun., 10(6) 1023-9; Johns et al., Chemistry, 2014, Jan. 13: 20(3):689-92; U.S. Patent Application Publication No. US 2013 / 0192978; Shi et al. J. Am. Chem. Soc. 2011, 133 (37) 14699-14703; Bao et al. RSC Adv., 2014, 4, 27277-27280;Luo et al. J. Mater. Chem.B, 2013, 1, 887-1001; Nunes et al., J. Am. Chem. Soc., 2009, 14331 (26) 9356-9462; Lauren et al., Acc. Chem. Res., 2002, 35, 19-27; U.S. Pat. No. 7,588,878; Prog. Polym. Sci. vol. 21, 1-45, 1996; and International Patent Application Publication No. WO2011 / 020928.

[0110] (iii) The use and location of carbon removal systems. The CO2 products produced from the disclosed carbon capture process can be used for a wide range of industrial applications and for carbon sequestration. Examples of industries that use large amounts of CO2 in their manufacturing processes include urea manufacturers (fertilizer production), methanol manufacturers, plastic manufacturers, and biofuel manufacturers. Often, these industries use CO2 from fossil sources such as the combustion of natural gas. Another industry that uses large amounts of CO2 is the oil industry, which pumps large amounts of CO2 into oil and natural gas wells to enhance the recovery of hydrocarbons (known as Enhanced Oil Recovery (EOR)). Often, EOR uses CO2 extracted from fossil reservoirs of CO2 underground. These industries are under increasing regulatory and investor pressure to decarbonize their processes and replace them with non-fossil fuel sources of CO2, and the use of CO2 captured from natural waters by the disclosed process would be beneficial to these industries in any case.

[0111] The CO2 captured by the process of the present disclosure can be used to enhance algae growth, which could improve the efficiency of algal biofuel production.

[0112] CO2 captured by the disclosed process could be used in the production of hydrocarbons and fuels from CO2, such as, for example, ethanol, long chain hydrocarbons, jet fuel, gasoline, and diesel. In one scenario, CO2 captured by the disclosed process is used in a Fischer-Tropsch process to produce such chemicals and fuels. In certain embodiments, the long chain hydrocarbons have more than 8 carbon atoms.

[0113] Cannabis cultivation is an important market for CO2. In greenhouse cultivation of cannabis, CO2 is added to the greenhouse air to promote plant growth. In many cases, this CO2 is obtained by burning biomass or fossil fuels. Then, eventually, the CO2 is released from the greenhouse into the environment, contributing to global warming and climate change. If CO2 captured from the atmosphere could be used for greenhouse cultivation of cannabis and other agricultural crops, the negative impact of increased CO2 on the climate could be reduced. The capture process of the present disclosure can increase the availability of CO2 in agriculture and reduce the climatic impact of the utilized CO2. By injecting the captured CO2 into a greenhouse or other related closed space, agricultural crops can be grown in an atmosphere enriched with CO2. The openings (stomata) in the leaves that transport CO2 become smaller in a CO2-rich environment, but are also one of the main routes of water loss. Thus, adding CO2 to the air around the plants by the process of the present disclosure can not only promote growth, but also limit water loss and improve drought resistance.

[0114] One suitable location for a carbon capture facility of the present disclosure is the Gulf Coast of the United States, where many oil and natural gas companies and fertilizer and methanol manufacturers operate. Locating a facility of the present disclosure in close proximity to end users of such captured CO2 products can reduce the costs and logistics of transporting the captured CO2 to end users. Additionally, there is CO2 sequestration capacity in depleted oil and natural gas wells under the Gulf of Mexico that can house thousands of gigatons of CO2, and many of the drilling and logistics support companies involved in oil and natural gas recovery are transitioning their infrastructure and business models to carbon sequestration in the near future.

[0115] Other suitable locations for the disclosed carbon capture facility include near geographic reservoirs where injection of captured CO2 leads to weathering and / or mineralization and long-term sequestration. Examples of such locations include basalt belts in eastern Washington, such as the Columbia River Basalt, near rivers with high concentrations of dissolved inorganic carbon (e.g., the Yakima River, the Snake River, the Columbia River, etc.). Other examples of such locations include offshore facilities near seafloor basalt, one of the most abundant types of host rock for CO2 mineralization on Earth. Offshore installations of seawater-based carbon capture processes such as those disclosed herein may allow CO2 to be produced in the ocean basalt belt for sequestration, reducing the need to transport CO2 to offshore locations. Yet another example is near an ultramafic rock outcrop in Oman, which is suitable for carbon sequestration via CO2 mineralization and is located near seawater.

[0116] It is cost-effective to configure the carbon capture facility of the present disclosure alongside facilities that already pump and discharge large amounts of seawater or river water, such as thermoelectric or nuclear power plants, or desalination plants. Such facilities could turn wastewater streams into revenue streams by providing the wastewater for subsequent carbon removal. Many such facilities exist along the east and west coasts of the United States, as well as along major rivers such as the Mississippi River, which is also a river with high dissolved carbon concentrations. Configurations alongside facilities that already pump and discharge large amounts of seawater are also beneficial in that the temperature of the wastewater is often higher than the intake water (e.g., because the intake water is often used to cool mechanical and chemical systems). Higher water temperatures are advantageous for the disclosed process, since higher water temperatures increase the partial pressure of CO2 in the water, which increases the efficiency of carbon removal in the disclosed process. Another advantage of configuring the carbon capture facility of the present disclosure alongside such facilities is that the head of the discharge water is often greater than zero. If the intake water of the provided system has some head, the disclosed process can be performed at less high pressure, reducing the energy cost of pumping. Head can also be provided by river flow or tides, impoundment of water in a dam or levee, or water from the spillway of a dam or levee.

[0117] Other applications of the disclosed carbon capture facilities and offshore co-location facilities include: -Offshore wind power generation facilities There has been an increase in offshore wind farms being installed worldwide to take advantage of wind power where wind energy is abundant and predictable and where large structures can be installed without the need for extensive land. Such facilities may generate more electricity than current demand requires, which may require curtailment of operations or may require costs to dispose of the excess electricity. The carbon capture facility of the present disclosure may be installed alongside the offshore wind farm, allowing the excess electricity to be used to run the carbon capture process. Advantages include the close proximity to seawater and the lack of need to acquire or lease land to implement the carbon capture of the present disclosure, thus reducing costs. - Vessels that capture carbon at sea and deliver it to end users and / or sequestration sites The carbon capture system of the present disclosure has a smaller form factor than direct air capture systems that require large fan farms, and the large amounts of seawater used in and discharged from a vessel's engine cooling systems can be useful as source water for the carbon capture system of the present disclosure. -Offshore oil drilling rigs These platforms are ideal for hosting the disclosed carbon capture facilities because they can be directly connected to depleted oil and natural gas wells that can sequester large amounts of CO2. These sites have unlimited seawater, which simplifies pumping, piping, etc. compared to land-based installations. -Floating solar power plant As the cost of coastal land rises, floating solar power plants are becoming more prevalent. Co-locating the disclosed carbon capture facility with an offshore (floating) solar power plant is beneficial because it is located near offshore saltwater aquifers and depleted oil and natural gas wells, shortening the distance the captured CO2 product must be transported. Also, because the seawater is located at the site, no transportation infrastructure is required. During times when such solar power plants generate more electricity than demand, such as midday, the excess power can be diverted to the disclosed carbon capture process, potentially reducing electricity costs. This environment also has the advantage of being offshore and close to marine basalt belts, which provide a large amount of surface host rock for carbon sequestration through weathering. -Naval vessels Current aircraft carriers are being built with nuclear reactors that can produce significantly more energy than is currently required for operation, and may be capable of producing synthetic fuels at sea. Several companies are developing synthetic fuel technologies, many of which use CO2 as one of the feedstocks. A Navy vessel configured with the disclosed carbon capture facility for fuel self-sufficiency at sea could receive an on-demand supply of raw materials. Excess power generated by the reactors could be used to power the most space-efficient form factor of the disclosed system, which employs a bank of LED lights.

[0118] The form factor of the system of the present disclosure is similar to that of a hybrid photovoltaic / thermal (PVT) panel (see, for example, FIG. 22). This form factor is preferred because it allows for mass production of modules of the carbon capture device of the present disclosure. Hybrid PVT panels are becoming more and more popular in homes and businesses because they can efficiently use incident sunlight for both power conversion (requiring only 20% of the incident solar energy) and hot water generation for use in swimming pools, home appliances, water heaters, etc. A significant synergistic effect can be achieved if the same panel uses sunlight to both activate the photochemical reaction of the present disclosure and generate electricity via photovoltaic power generation. Such a configuration is feasible because the photochemical reaction of the present disclosure requires only about 15-20% of the incident solar spectrum. The remainder of the incident solar spectrum can be used to generate electricity using a photovoltaic panel installed under a photoacid chamber (e.g., about 1 cm thick). By installing a fluid chamber above or below the photovoltaic panel, the panel can be cooled, improving the efficiency of photovoltaic power generation. The heat produced can be used to heat the carbon-containing liquid to increase its pCO2, increasing the efficiency of CO2 transfer from the source fluid to the target stream.

[0119] Photoacidification can be used as part of other carbon removal techniques to enhance the weathering rate of minerals. One approach being researched and developed for removing CO2 from the atmosphere is the weathering of calcium carbonate (limestone) or ultramafic rocks (i.e., those with a color index greater than 90). This process exploits the CO2 neutralizing ability of certain minerals, such as calcium carbonate and olivine, among others. One of the reasons this approach is inefficient for carbon removal is that these minerals react slowly with CO2. Many weathering reactions can be accelerated by adding acid or additional CO2 to the aqueous solution that is added to the finely ground mineral. The disclosed process of generating acid by activating a photoacid with light can be used to obtain the acidity and / or high CO2 concentration required to enhance the dissolution and weathering rate of materials such as ultramafic rocks and calcium carbonate. This may enhance the rate of carbon dioxide removal at weathering facilities. Minerals may be exposed to a target solution with increased acidity due to the action of a photoacid. In one embodiment, the photoacid is activated in a sub-solution to cause the photoacid to generate protons. The protons are then transferred through the membrane to the target solution, lowering the pH of the target solution and accelerating weathering, which removes carbon through known geochemical processes. The photoacid may also be immobilized on a surface in contact with the target solution, such as a bead, plate, or the target solution side of the membrane.

[0120] Exemplary embodiments 1. A method for removing carbon from a carbon-containing liquid, comprising: 13. A method comprising removing carbon from a carbon-containing liquid by exposing the carbon-containing liquid to a photoactive compound and transferring the carbon to a second environment. 2. The method of embodiment 1, wherein the second environment comprises a target flow or working fluid. 3. The method of embodiment 2, wherein the target stream is a liquid or a gas. 4. The method of embodiment 2 or 3, wherein the second environment is a target stream and the removal of carbon by transferring the carbon to the target stream is performed via a membrane or gas contact, or by direct transfer. 5. The method of any of embodiments 2-4, wherein the second environment is a working fluid and the removal of carbon by transferring the carbon to the working fluid is performed via a membrane. 6. The method of embodiment 5, wherein the membrane is a gas-permeable membrane. 7. The method of embodiment 5 or 6, wherein the membrane is an ion exchange membrane. 8. The method of any one of embodiments 2-7, wherein the working fluid is interposed between the carbon-containing liquid and the target stream. 9. The method of embodiment 8, wherein the working fluid is separated from the carbon-containing liquid by a membrane. 10. The method of embodiment 8 or 9, wherein the working fluid is separated from the target stream by a membrane or a gas interface. 11. The method of any of embodiments 8-10, wherein the working fluid is separated from the carbon-containing liquid by a membrane and from the target stream by a membrane or gas contact. 12. The method of any one of embodiments 2-11, wherein the photoactive compound is disposed in the working fluid. 13. The method of any one of the preceding embodiments, wherein the photoactive compound is disposed in the carbon-containing liquid or at a border with the carbon-containing liquid. 14. The method of any one of the preceding claims, wherein the photoactive compound is disposed in a secondary fluid that is separated from the carbon-containing liquid. 15. The method of embodiment 14, wherein the secondary fluid and the carbon-containing liquid are separated by an ion exchange membrane. 16. The method of embodiment 15, wherein the ion exchange membrane is a cation exchange membrane through which protons diffuse. 17. The method of any of embodiments 13-16, wherein the photoactive compound reduces the pH of the carbon-containing liquid. 18. The method of any of the preceding embodiments, wherein the photoactive compound is an activated photoactive compound. 19. The method of embodiment 18, wherein the activated photoactive compound generates protons that diffuse through a membrane into the carbon-containing liquid, thereby lowering the pH of the carbon-containing liquid and removing carbon. 20. The method of any one of the preceding embodiments, wherein the photoactive compound comprises a photoacid. 21. The method of embodiment 20, wherein the photoacid comprises a reversible photoacid. 22. The method of embodiment 20 or 21, wherein the photoacid comprises a metastable photoacid. 23. The method of any one of the preceding embodiments, wherein the photoacids comprise merocyanines, spiropyrans, tricyanofurans, fulgides, diarylethenes, azobenzenes, spirooxazines, quinones, or triphenylmethanes. 24. The method of any one of the preceding embodiments, wherein the photoactive compounds comprise merocyanines. 25. The method of embodiment 24, wherein the merocyanines have a methoxy substituent on the indolinium ring and a butylsulfonate group on the nitrogen atom of the indolinium ring. 26. The method of any one of the preceding embodiments, further comprising activating the photoactive compound. 27. The method of embodiment 26, wherein activating the photoactive compound comprises exposing the photoactive compound to light. 28. The method of embodiment 27, wherein the light is sunlight or artificial light. 29. The method of embodiment 28, wherein the artificial light is from light emitting diode (LED) lighting. 30. The method of embodiment 29, wherein the light is sunlight and the photoactive compound is a plurality of photoactive compounds each having a different absorption spectrum. 31. The method of any of the preceding embodiments, wherein the photoactive compound is embedded within a material and / or coated on a surface of a material. 32. The method of embodiment 31, wherein the material comprises beads, granules, tubes, plates, or membranes. 33. The method of embodiment 31 or 32, wherein the material comprises the gas-permeable membrane of embodiment 7. 34. The method of any one of embodiments 31 to 33, wherein the material comprises the ion exchange membrane of embodiment 8. 35. The method of any one of embodiments 31-34, wherein the material is disposed in the carbon-containing liquid of embodiment 13. 36. The method of any one of embodiments 31 to 35, wherein the material is disposed at the interface in contact with the carbon-containing liquid of embodiment 13. 37. The method of any one of embodiments 31-36, wherein the material is disposed in the secondary fluid of embodiment 14. 38. The method of any one of embodiments 17-37, wherein the decrease in pH increases the partial pressure of carbon dioxide in the carbon-containing liquid. 39. The method of any one of the preceding embodiments, wherein the reduced pH is in the range of 2 to 7. 40. The method of any one of the preceding embodiments, wherein the reduced pH is in the range of 3 to 6. 41. The method of any of the preceding embodiments, further comprising directing a flow of the carbon-containing liquid towards the activated photoactive compound. 42. The method of any one of the preceding embodiments, further comprising heating the carbon-containing liquid with a heat source. 43. The method of embodiment 42, wherein the carbon-containing liquid is heated to a temperature in the range of -2°C to 120°C. 44. The method of embodiment 42 or 43, wherein the heat source comprises solar thermal energy or waste heat from a power generation or industrial process. 45. The method of embodiment 44, wherein the power generation is thermoelectric or nuclear power generation. 46. ​​A method for accelerating a weathering reaction of a mineral, the method comprising the step of accelerating a weathering reaction of the mineral by exposing the mineral to a target liquid that has been exposed to a photoactive compound that reduces the pH of the target liquid. 47. A method of recovering carbon, comprising concentrating carbon recovered from another gas or fluid in a target liquid by exposing minerals to the target liquid that has been exposed to a photoactive compound that reduces the pH of the target liquid. 48. The method of embodiment 46 or 47, wherein the mineral is a pulverized mineral. 49. The method of any one of embodiments 46 to 48, wherein the mineral is ultramafic rock and / or limestone and / or olivine. 50. The method of any of embodiments 46-49, wherein the carbon source is combustion of fossil fuels and / or biofuels. 51. The method of any one of embodiments 46-50, wherein the carbon source is an industrial process. 52. The method of embodiment 51, wherein the industrial process is the production of cement. 53. The method of any one of embodiments 46-52, wherein the carbon source is air. 54. The method of any one of embodiments 46-53, wherein the carbon source is a liquid. 55. The method of embodiment 54, wherein the liquid is seawater. 56. The method of any of embodiments 46 to 55, wherein the photoactive compound is disposed in the mineral-containing target liquid or at a boundary in contact with the mineral-containing target liquid. 57. The method of any of embodiments 46-56, wherein the photoactive compound is disposed in a secondary fluid that is separated from the target liquid. 58. The method of embodiment 57, wherein the secondary fluid and the target liquid are separated by a cation exchange membrane, and the protons diffuse through the interior of the cation exchange membrane. 59. The method of any one of the preceding embodiments, further comprising recovering the removed carbon. 60. The method of embodiment 59, wherein the step of recovering the removed carbon is performed after inactivation of the photoactive compound. 61. The method of any of embodiments 18-60, further comprising the step of inactivating the photoactive compound. 62. The method of embodiment 61, wherein the deactivating step comprises ceasing exposure to light of the photoactive compound. 63. The method of embodiment 61 or 62, wherein the steps of activating the photoactive compound and deactivating the photoactive compound are performed sequentially based on the direction of flow of the carbon-containing liquid, and the step of recovering the removed carbon is performed between the steps of activating the photoactive compound and deactivating the photoactive compound. 64. The method of embodiment 62 or 63, wherein the step of removing the light from the photoactive compound restores the photoactive compound to its relaxed state, thereby regenerating the photoactive compound for further use in the method of embodiment 1. 65. The method of embodiment 64, further comprising the steps of activating the regenerated photoactive compound and reversing the direction of flow of the carbon-containing liquid after regeneration of the photoactive compound to further remove carbon. 66. The method of any one of embodiments 2-65, further comprising maintaining the charge balance of the working fluid. 67. The method of any one of embodiments 14-66, further comprising maintaining the charge balance of the secondary fluid. 68. The method of embodiment 66 or 67, wherein the step of maintaining the charge balance comprises replacing protons transferred from the working fluid or the secondary fluid to the carbon-containing fluid with cations, or transferring anions to the carbon-containing fluid together with the protons transferred from the working fluid or the secondary fluid. 69. The method of embodiment 68, wherein the cations or anions are from another carbon-containing fluid or from another fluid. 70. The method of any one of embodiments 66-69, wherein maintaining the charge balance of the working fluid or the secondary fluid comprises using an electrochemical reaction. 71. The method of embodiment 70, wherein the electrochemical reaction occurs based on the presence of an anode or a cathode. 72. The method of any of embodiments 14-71, further comprising contacting the secondary fluid with a fluid stream through an ion exchange membrane, the fluid stream comprising a source of protons. 73. The method of any one of the preceding embodiments, wherein the carbon in the carbon-containing liquid is in the form of carbon dioxide, carbonic acid, bicarbonate, and / or carbonate. 74. The method of any one of the preceding embodiments, wherein the removed carbon is carbon dioxide. 75. The method of any one of the preceding embodiments, wherein the carbon-containing liquid is water. 76. The method of embodiment 75, wherein the water is seawater, ocean water, or river water. 77. The method of embodiment 75 or 76, wherein the water is brackish. 78. The method of any one of embodiments 75-77, wherein the water is wastewater from a power generation process or an industrial process. 79. The method of embodiment 78, wherein the power generation process is thermoelectric or nuclear power generation. 80. The method of embodiment 78 or 79, wherein the industrial process is desalination. 81. A system for carrying out the method according to any one of embodiments 1 to 80. 82. A system for removing carbon from a carbon-containing liquid, comprising: a duct for transporting the carbon-containing liquid to the photoactive compound; A material comprising the photoactive compound; A stimulator for activating the photoactive compound contained in the substance; A system comprising: 83. The system of embodiment 82, further comprising a recovery unit for recovering the removed carbon. 84. The system of embodiment 82 or 83, further comprising a flow device for flowing the carbon-containing liquid toward the photoactive compound. 85. The system of any of embodiments 82-84, wherein the flow device comprises a pump or a hydraulic head. 86. The system of embodiment 85, wherein the hydraulic head is generated by a tidal current, a river, or a dam. 87. The system of embodiment 85 or 86, wherein the flow device generates convection of a heated fluid. 88. The system of any of embodiments 83-87, further comprising a material between the capture unit and the target stream, the material enabling the removal of carbon to be transferred from the capture unit to the target stream. 89. The system of embodiment 88, wherein the material comprises a membrane, a gas contact, or a material that allows the removed carbon to be transferred directly to the target stream. 90. The system according to any of embodiments 82-89, further comprising a second duct for transporting the working fluid or the secondary fluid. 91. The system of embodiment 90, further comprising a third duct for transporting the working fluid or the secondary fluid. 92. A system described in any one of embodiments 82 to 91, wherein the stimulation unit is equipped with a light source. 93. The system of embodiment 92, wherein the light source is an artificial light source. 94. The system of embodiment 93, wherein the artificial light source is an LED light source. 95. The system of any of embodiments 82-94, further comprising a heat source for heating the carbon-containing liquid. 96. The system of embodiment 95, further comprising a fourth duct for transporting the carbon-containing liquid to the heat source. 97. A system for removing carbon from a carbon-containing liquid, comprising: a first duct for transporting a carbon-containing liquid; a stimulator for activating the photoactive compound; A processor; A computer-readable recording medium having computer-executable instructions stored thereon; Equipped with The computer-executable instructions, when executed, exposing the carbon-containing liquid in the first duct to a photoactive compound; and removing carbon from the carbon-containing liquid and transferring it to a second environment. system. 98. The stimulation unit includes a light source; 98. The system of embodiment 97, wherein the operation further comprises activating the photoactive compound with the light source. 99. A flow device for flowing the carbon-containing liquid is further provided. 99. The system of embodiment 97 or 98, wherein the operation further comprises using the flow device to direct a flow of the carbon-containing liquid toward the activated photoactive compound. 100. The system of any one of embodiments 97-99, wherein the operation further comprises deactivating the photoactive compound by ceasing exposure of the photoactive compound to the light source. 101. The method further comprises a recovery unit for recovering the removed carbon; 101. The system of any of embodiments 97-100, wherein the operations further comprise recovering the removed carbon using the recovery unit. 102. The system of embodiment 101, wherein recovery of the removed carbon is carried out after inactivation of the photoactive compound. 103. The second environment includes a target stream; the system further comprising a material between the collection unit and the target stream; 103. The system of any one of embodiments 97-102, wherein the operation further comprises transferring the removed carbon from the capture unit through the material to the target stream for a predetermined period of time. 104. The system of embodiment 103, wherein the material comprises a membrane, a gas contact, or a material capable of transferring the removed carbon directly to the target stream. 105. A method for producing a carbon-containing liquid, comprising: 105. The system of any one of embodiments 97-104, wherein the operation further comprises heating the carbon-containing liquid with the heat source. 106. The second environment includes a working fluid; The system further comprises: a second duct for transporting the working fluid; a membrane in operative contact with the secondary fluid comprising the photoactive compound; exposing the carbon-containing liquid to the photoactive compound; 106. The system of any of embodiments 97-105, comprising exposing the carbon-containing liquid to the membrane when the secondary fluid is at a higher pH state for a time sufficient to remove carbon from the carbon-containing liquid and transfer it to the working fluid. 107. Further comprising a pump or a water head; 107. The system of any one of embodiments 97-106, wherein the operation further comprises using the pump or the head to break the functional contact between the membrane and the secondary fluid. 108. The system of any one of embodiments 82 to 107, further comprising a solar power generation panel. 109. The system of embodiment 108, wherein the photovoltaic panel is disposed beneath the material comprising the photoactive compound. 110. The system of embodiment 108 or 109, wherein the photovoltaic panel is translucent and disposed on the material containing the photoactive compound. 111. The system of any one of embodiments 82-110, wherein the photoactive compound is a plurality of photoactive compounds, each having a different absorption spectrum. 112. The system of any one of embodiments 82-111, wherein the material comprising the photoactive compound further comprises a mineral. 113. The system of embodiment 112, wherein the mineral is a crushed mineral. 114. The system of embodiment 112 or 113, wherein the mineral is ultramafic rock and / or limestone. 115. The system of any of embodiments 82-114, within 1000 miles, 100 miles, 50 miles, 40 miles, 30 miles, 20 miles, 10 miles, 5 miles, 2 miles, or 1 mile of a carbon sequestration site. 116. The system of embodiment 115, wherein the carbon sequestration site is in an ocean, sea, river, or continental crust. 117. The system of embodiment 115 or 116, wherein the carbon sequestration site is in bedrock. 118. The system of embodiment 117, wherein the bedrock is in an ocean, sea, or river, or on the bottom of an ocean, sea, or river. 119. The system of embodiment 117 or 118, wherein the rock formation is a hydrocarbon-producing rock formation. 120. The system of embodiment 119, wherein the hydrocarbon producing rock formation is utilized for enhanced oil recovery (EOR). 121. The system of any of embodiments 117-120, wherein the bedrock comprises a saline aquifer. 122. The system of any of embodiments 115-121, wherein the carbon sequestration sites are in depleted oil and natural gas wells. 123. The system of any of embodiments 115-122, wherein the carbon sequestration site is in a saline aquifer. 124. A system described in any of embodiments 82-123, within 10 miles, within 5 miles, or within 2 miles of a coastline. 125. The system of any of embodiments 82 to 124, installed on an offshore oil drilling rig, an offshore wind farm, a ship, an offshore structure, or a floating solar power plant. 126. The system of embodiment 125, wherein the vessel is a naval vessel. 127. Use of carbon removed from a carbon-containing liquid by the method according to any one of embodiments 1 to 80 as a component of a product. 128. The use according to embodiment 127, wherein the product is a fertilizer, a plastic, a cement, or a fuel. 129. The use of embodiment 128, wherein the fuel is biofuel, petroleum, gasoline, diesel fuel, jet fuel, or synthetic fuel. 130. The use according to embodiment 129, wherein the biofuel is an algal biofuel. 131. The use according to any of embodiments 127 to 130, wherein the product is methanol, ethanol, or hydrocarbons. 132. The use according to embodiment 131, wherein the hydrocarbons are long-chain hydrocarbons. 133. Use of carbon removed from a carbon-containing liquid by the method according to any of embodiments 1 to 80 in the growth of organisms. 134. The use according to embodiment 133, wherein the organism is an algae. 135. The use according to embodiment 133, wherein the organism is a crop plant. 136. The use according to embodiment 135, wherein the crop is an agricultural crop. 137. The use according to embodiment 133, wherein the organism is a plant. 138. The use according to embodiment 137, wherein the plant is a cannabis plant. 139. The use according to any of embodiments 133 to 138, which is carried out in greenhouse cultivation. EXAMPLES

[0121] Example 1. Overall carbon capture process In the first step of the chemical cycle (FIG. 17), visible light excites a reversible photoacid, releasing protons. These protons acidify seawater or other carbon-containing liquid, lowering the pH of the source liquid and converting the dissolved carbon in the source liquid to CO2 gas. The CO2 gas is removed from the source liquid by passive diffusion, for example through a commercially available gas contacting membrane. Meanwhile, when the light is removed from the photoacid, the photoacid spontaneously relaxes and reverts back to a more basic form. The cycle completes by regenerating the now basic form of the photoacid using the spent source liquid. In some embodiments, this regeneration can also be performed using other fluids, such as seawater, that are not otherwise part of the process. In embodiments using seawater as a carbon source fluid, the carbon-reduced seawater is returned to the ocean, providing an added benefit of being a regional countermeasure to ocean acidification. The following description will be focused on one embodiment of the disclosed process in which the photoacid is dissolved in a secondary fluid. Other examples contemplate configurations in which the photoacid is immobilized on the surface of a substrate or embedded in a material, but the overall cycle can be configured similarly to that described here.

[0122] More specifically, in acidification, a reversible photoacid adds protons to seawater or other liquids that contain dissolved carbon, resulting in the formation of Na +or other cations (FIG. 18). This process can be carried out, for example, via a cation exchange membrane. This process is electronically neutral, i.e., an equal amount of positive charge is simultaneously lost and gained, thus avoiding potentials that slow the rate of oxidation. In hydrochemical terms, this cation exchange step is equivalent to removing alkalinity from the incoming seawater. In regeneration, an equal amount of alkalinity is returned to the outgoing seawater by a similar but reverse proton and cation exchange process. Thus, alkalinity is transferred between steps of the disclosed process, but alkalinity is not added or removed from the ocean as a whole. Many configurations that would change the overall ocean alkalinity can be avoided by requiring large chemical inputs or large wastewater streams. This is one of the important advantages of the disclosed process. The disclosed process involves a series of cycles that transfer alkalinity between samples of one fluid or between separate fluids using light and photoacid (FIG. 18). Additional details and supporting experimental results are provided below in the chapters on the specific steps of the process.

[0123] One scenario for the implementation of the process of the present disclosure, obtained through process modeling, is presented here with details on the process flow and chemistry.

[0124] Excitation of photoacid in the photoreaction section to produce protons Reversible photoacids (RPAs) react in solution to form several different chemical species. Examples of such species include ground state protonated species (GSH), ground state deprotonated species (GS), and excited state deprotonated species (ES). In the disclosed chemical process, light is used to excite the GSH species of the RPA to the ES species, which releases a proton and makes the solution more acidic with a lower pH. For a number of different RPAs, the laboratory has demonstrated that irradiating the reversible photoacids with light can lower the pH of the solution, which can be increased or decreased by repeating light / dark cycles.

[0125] Which component of the incident light induces the desired reaction is one of the important performance parameters of the photoreaction. This performance is controlled by: the component of the incident light that matches the absorption spectrum of the GSH photoacid; the amount of incident light that is absorbed, which is a function of the extinction coefficient, path length, and concentration of the absorbing species; and the component of the absorbed light that produces the desired photoreaction (quantum yield, φ). Existing RPAs are typically excited with blue visible light and have large extinction coefficients (10 4 L mole -1 cm -1 A large extinction coefficient means that these compounds efficiently absorb light near their maximum excitation wavelength (λmax = 425 nm for the photoacid in this example). The length scale for 99% decay of incident light at λmax in a solution of RPA is approximately 10, a typical RPA property. 4 Calculated using 2 mmol of the water solubility of the GSH species, this is about 1 mm. Previous studies by the laboratory have demonstrated that incident blue light is totally attenuated and excitation of GSH to ES occurs with a maximum quantum yield of 0.7 (Berton et al., 2020). This property means that the optical path length of light through a solution containing RPA in the GSH state only needs to be a few millimeters to design a practical and compact photoreaction unit that efficiently releases protons. In other examples, light may be irradiated onto RPA immobilized on the surface of a material or incorporated into the material. The high extinction coefficient and high quantum yield of RPA mean that a thin layer of RPA can be effective in these examples.

[0126] Many RPAs are photochromic, so the optical path length and dimensions of the photoreaction section can be flexibly modified to exceed 1 mm. In photochromic compounds, the absorption spectrum of the ground state species is significantly different from that of the excited state species. This shift in absorption limits self-shielding. Photochromic RPAs that convert to the ES state do not attenuate light at the wavelengths that best match GSH excitation. Thus, even if the thickness of the RPA solution is thicker than the characteristic 1 mm mentioned above, light can still penetrate the RPA solution and react with the remaining GSH species.

[0127] The optimal size and design of the photoreactor will also take into account other factors such as whether the RPA is dissolved in solution or immobilized on a substrate, the flow rate and mixing if the RPA is dissolved in solution, the optical path of the incident light, the source, intensity, and wavelength of the incident light, whether the photoreactor is incorporated into other aspects of the disclosed process, and whether the photoreactor is incorporated into other industrial processes. An example of combining several steps of the process in a modular panel is shown in FIG.

[0128] FIGURE 21 illustrates an embodiment of an exemplary carbon capture system of the present disclosure that acidifies source water in a row of carbon capture devices as illustrated in FIGURE 20 and transports the acidified source water to a central gas transport facility. The gas transport devices are centrally located to minimize gas transport piping and capital costs. In one embodiment, thermosiphons are used to recirculate the light acid solution within each panel, eliminating the need to pump fluids manually, reducing electrical demand and potentially reducing capital costs for water pumps.

[0129] Use of artificial light sources Light for the RPA excitation reaction can be provided by sunlight or an artificial light source. An example of an artificial light source is a light emitting diode (LED). Advantages of using an LED include a compact photoreactor design and the ability to closely match the wavelength of the light source to the absorption spectrum of the RPA. High brightness blue LEDs that match the absorption spectrum of existing RPAs are commercially available. For example, OSRAM's OSLON GD CSBRM2.14 Deep Blue is a commercially available LED with a peak emission of 445 nm that may function well in the process of the present disclosure. This LED typically has an efficiency of 70%, which means that when driven with 2 W of input electrical energy, this LED produces a central light energy of 1.4 watts (J / sec). In one embodiment, a 500W / m2 LED produces 1860 μmoles of photons per square meter per second and consumes 720 watts of power. 2 A LED array of 10 ... 2 ) × (95% predicted value of photocoupling between the light source and the photoreaction solution) × (quantum yield 0.7) = 1237 μmol / sec m of ES and proton production 2 At a commercial electricity rate of $0.06 per kilowatt hour, the cost of electricity is $0.043 / hour. Assuming that the protons produced in this reaction are 85% efficient at moving CO2, a 1 square meter LED array will move 1237 μmoles of protons / sec x (85%) x (60 sec / min) x (60 min / hr) = CO 2 The production rate of CO2 is 3.79 moles per hour, or 167 grams per hour. One tonne of CO2 is 10 6g, so the LED electricity cost per tonne of CO2 in this scenario is $259 per tonne of CO2 captured. In this example LED array system, the area of ​​LED lighting required for a facility producing 1 kilotonne of CO2 per year is 685 m 2 Assuming each module panel is 10cm high, the system can be fitted into a volume 3m high and 5m long and wide, roughly the same volume as a standard 40-foot high-cube shipping container.

[0130] Sunlight as a light source Using sunlight to excite the photoacid is an energy efficient option that can reduce operating costs since no energy or cost is required to operate LEDs or other artificial lights. However, only a portion of the sunlight spectrum matches the absorption spectrum of GSH photoacid, sunlight is only available for a limited time of day, and sunlight is less bright than many artificial light sources, so the area required to collect sufficient light can be large. The choice of sunlight and / or artificial light will depend on the specific application and will take into account factors such as energy costs, availability of sunlight, land availability, size constraints, and capital costs associated with manufacturing the photoreactor.

[0131] The following table shows typical solar availability at several locations near ocean waters or rivers that contain dissolved CO2. [Table 1]

[0132] Direct solar radiation is 6.0kWh / m 2 day, i.e., 2200 kWh / m 2San Diego, 2015, is shown as a design example. Existing photovoltaics are expected to absorb approximately 13% of the Earth's surface solar spectrum. Illustrated calculations are for the collector area required for a facility producing 1 kilotonne of CO2 per year in a solar-available location such as San Diego. Using these parameters for these calculations, it would take 10,000 m2 of solar collector area to concentrate the sunlight required for a facility producing 1 kilotonne of CO2 per year. 2 , which means an area roughly the size of two American football fields is required. (2200 kWh / year m 2 )(light loss 0.95)(effective solar spectrum 13%)(attenuation rate 100%) = effective radiation absorbed by the photoacid 272 kWh / year m 2 (Absorbed radiation 272 kWh / year m 2 )(1000 Wh / 1 kWh)(3,600 J / 1 Wh)= absorbed radiation x 10 9 J / year m 2 (Absorbed radiation dose 1 × 10 9 J / year m 2 ) / (Energy per photon at 430 nm above: 4.62 × 10 -19 J) (1 mole / number of photons 6.02 × 10 23 ) = 3,706 moles of photons per square meter per year (3,706 moles of photons absorbed per square meter per year)(quantum yield 0.7) x (CO2 conversion rate 0.85) = 2,205 moles of CO2 produced per square meter per year A facility producing 1 kilotonne of CO2 per year requires 22.7 × 10 6 moles / year required, so solar collecting area required = (22.7 x 10 6 moles / year) / (moles of CO2 2.20 × 10 3 / year m 2 )=10,307 m 2 Area of ​​one American football field = 360 ft x 160 ft = 57,600 sq ft. This is 57,600 sq ft / (3.28 ft / m) / (3.28 ft / m)= 5,354 m 2 In other words, a facility that produces 1 kiloton of CO2 using this technology would require 10,307 m 2 ) / (5,353 m 2 ) = A solar collecting area equivalent to 1.9 American football fields is required. In this scenario, the solar energy harvesting would require an area 15 times larger than the surface area of ​​the LED implementation. In particular, the solar collection area cannot be stacked and made compact as in LED and other artificial light source scenarios.

[0133] One way to improve the efficiency of solar-powered processes is to use multiple photoacids with different absorption spectra (different lambda max) to harvest more of the solar spectrum. This approach is supported by research showing that chemical changes to the RPA structure can shift the lambda max (Liu, Junning, Wenqi Tang, Lan Sheng, Zhen Du, Ting Zhang, Xing Su, and Sean Xiao‐An Zhang. “Effects of Substituents on Metastable-State Photoacids: Design, Synthesis, and Evaluation of Their Photochemical Properties.” Chemistry‐An Asian Journal 14, no. 3 (February 2019): 438-45. doi.org / 10.1002 / asia.201801687.).

[0134] In another embodiment to use the solar energy more efficiently, the photoreactor may be combined with a photovoltaic panel (FIG. 22). This embodiment is similar to commercially available hybrid solar / thermal concentrator panels used to simultaneously generate electricity and heat water. For example, a solar panel may be placed under the solution containing the RPA. Sunlight not absorbed by the RPA passes through the solution and is absorbed by the PV concentrator to generate electricity. This approach may utilize the solar energy to both capture carbon and generate electricity. This approach may increase the profitability and environmental friendliness of the system. In an alternative embodiment, instead of placing a PV panel under the RPA solution, a special semi-transparent solar PV panel is placed on top of the RPA solution.

[0135] CO2 diffusion Extensive laboratory and field tests were performed with relevant seawater flow rates to show that the diffusion process does not require an outer membrane or high pressure and can be achieved using commercially available components. In this experiment, CO2 was extracted from seawater using a commercially available gas contactor membrane (Separel EF-040p-Q-AN, made in Japan), which is permeable to CO2 but not to water or ions. Carbon dioxide passively diffuses through a 40 μm thick poly-4-methyl-pentene-1 (PMP) membrane that separates the inside and outside of the device. The EF-040p-Q-AN membrane used has a surface area of ​​40 m 2 Although smaller and larger sizes are available commercially. A pump is used to transport seawater to the outside of the membrane, and a small flow of sweep gas (air in this example) is pulled through the inside of the device using a liquid ring laboratory vacuum pump (Welch 2585B) located downstream of the membrane. In other tests, a sweep gas was pumped through the membrane using a pump located upstream of the gas contact. In other tests, a vacuum was applied to the inside of the membrane without a sweep gas. Similar CO2 transfer efficiencies from liquid to gas were obtained whether the gas side of the membrane was subjected to a vacuum or positive pressure (>1 atm).

[0136] As CO2 moves from the water side to the air side of the gas contact membrane, the dissolved inorganic carbon (DIC) in the water decreases, but the alkalinity does not change. Therefore, the carbon flux through the membrane can be calculated by multiplying the decrease in DIC between the seawater flowing into the contact area and the seawater flowing out of the contact area by the water flow rate, using Equation 1.

number

[0137] The carbon flux through the membrane was also calculated separately from the pCO2 of the gas exiting the inner side of the membrane. The two independent estimates were in good overall agreement, indicating that the carbon flux can be accurately measured. The experimental data were also compared to a numerical model of the membrane gas contactor, which is responsible for the advection, diffusion, and chemical reactions of inorganic carbon. In this model, seawater and the sweep gas are separated into separate boxes in the gas contactor. Seawater and the sweep gas are advected in opposite directions by convection. CO2 is transferred between the seawater and the sweep gas by diffusion through the membrane. Inorganic carbon in each well-stirred seawater box is subjected to kinetic and equilibrium chemical reactions. The validated numerical model can be used to predict carbon transfer rates over a wide range of conditions and can be a design aid for process optimization.

[0138] In one set of experiments, seawater was acidified such that its alkalinity was reduced from 2300 to 300 μeq / kg, corresponding to the approximate levels predicted by the disclosed process. Carbon flux increased significantly upon acidification of the seawater. For example, the carbon flux rate was 25 μmoles CO2 / min m2 to the membrane in pre-acidified seawater, holding other experimental conditions constant. 2 After acidification, the CO2 concentration in seawater was 825 μmol / min m 2These experiments demonstrate one of the fundamental principles of the disclosed process, that CO2 removal from natural waters can be enhanced by acidification. One factor that distinguishes the disclosed process from other technologies is that the acidification is accomplished using a reversible photoacid. Furthermore, the experimental data demonstrates that the carbon removal rate was 860 μmol CO2 / min m for acidified seawater under these experimental conditions. 2 The results were in good agreement with a numerical gas transport model that predicted the following, with an accuracy error of less than 5%.

[0139] For a given acidification level, the highest carbon flux could be removed from seawater by the Separel EF-040p-Q-AN membrane at maximum seawater flow rate, maximum seawater heating, and a vacuum strength of approximately 0.85 atm (Figure 23).

[0140] Measurements were conducted several months later using different membranes of the same design at different locations, using both natural seawater from the location and artificial seawater from our institute, and the results were compared with those modeled above. The carbon flux was reproducible, confirming that it is possible to predict CO2 removal from seawater.

[0141] Degradation of photoacids and properties of ideal photoacids One factor to consider in implementing the process of the present disclosure is photoacid degradation. Current RPA is known to hydrolyze in aqueous solutions on a time scale of hours to days. At such rates, replacement of RPA may be cost prohibitive for some applications. Modifying the structure of RPA may slow this degradation reaction (Berton, et al. 2021). The main degradation pathway is known (Berton, et al. 2020) and is simply a reversal of the last synthetic step that produces RPA (Figure 24). That is, the product of the degradation reaction is the starting material for the last step of RPA synthesis. This means that it may be possible to recover the product from the degradation reaction to regenerate RPA. RPA is also stable for months in some non-aqueous solvents, such as acetonitrile. Other approaches to limit degradation are to use non-aqueous solvents or mixtures of non-aqueous and aqueous solvents as the working fluid containing RPA. Immobilizing RPA on a surface or within a material also has a positive effect on the degradation rate.

[0142] Conclusion Unless otherwise indicated, the practice of the present disclosure may employ conventional techniques of chemistry, organic chemistry, biochemistry, analytical chemistry, physical chemistry, and electrochemistry. These methods are described in the following publications: Harcourt, et al., Holt McDougal Modern Chemistry: Student Edition (2018); J. Karty, Organic Chemistry Principles and Mechanisms (2014); Nelson, et al., Lehninger Principles of Biochemistry 5th edition (2008); Skoog, et al., Fundamentals of Analytical Chemistry (8th Edition); Atkins, et al., Atkins' Physical Chemistry (11th Edition); Lefrou, et al., Electrochemistry: The Basics, with Examples, 2012, Anslyn and Dougherty, Modern Physical Organic Chemistry.

[0143] Some or all of the operations of the above methods may be performed by the execution of computer readable instructions stored on a computer readable recording medium, as defined below. As used herein, the term "computer readable instructions" encompasses routines, applications, application modules, program modules, programs, components, data structures, algorithms, etc. The computer readable instructions may be implemented on a variety of systems, including single or multi-processor systems, minicomputers, mainframe computers, personal computers, portable computing devices, microprocessor-based programmable consumer electronics, and combinations thereof.

[0144] The computer-readable recording medium may include volatile memory (such as random access memory (RAM)) and / or non-volatile memory (such as read-only memory (ROM), flash memory, etc.). The computer-readable recording medium may further include removable and / or non-removable recording media capable of providing non-volatile storage of computer-readable instructions, data structures, program modules, etc., examples of such removable and / or non-removable recording media include, but are not limited to, flash memory, magnetic storage devices, optical storage devices, and / or tape storage devices.

[0145] A non-transitory computer-readable recording medium is an example of a computer-readable recording medium. A computer-readable recording medium includes at least two types of computer-readable recording media: computer-readable recording media and communication media. A computer-readable recording medium includes volatile and non-volatile, removable and non-removable media implemented in any process or technology that records information such as computer-readable instructions, data structures, program modules, or other data. Examples of computer-readable recording media include phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any other non-transmission medium that can be used to store information accessed by a computing device. Alternatively, communication media may embody computer-readable instructions, data structures, program modules or other data in a modulated data signal, such as a carrier wave or other communication mechanism. As defined herein, computer-readable media does not encompass communication media.

[0146] The computer readable instructions stored on one or more non-transitory computer readable recording media, when executed by one or more processors, may perform the operations described above with reference to the figures. Generally, computer readable instructions include routines, programs, objects, components, data structures, etc. that perform particular functions or provide particular abstract data types. The order in which the operations are described is not intended to be construed as a limitation, and the steps described above may be performed in any number and combination, in any order, and / or in parallel to implement the process.

[0147] Each embodiment disclosed herein may comprise, consist essentially of, or consist of the particular components, steps, materials, or ingredients described. Thus, the terms "includes" or "including" should be interpreted as describing "comprising, essentially consisting of, or consisting of." The transitional phrase "comprising" means having, but is not limited to, and means that unspecified components, steps, materials, or ingredients may be included, even if they are greater in amount / number. The transitional phrase "consisting of" means that unspecified components, steps, materials, or ingredients are not included. The transitional phrase "consisting essentially of" limits the scope of the embodiment to the components, steps, materials, or ingredients specified and those that do not have a significant effect on the embodiment. A significant effect is an effect that may statistically significantly reduce the efficiency of removing carbon from a carbon-containing liquid and transferring it to a target gas or liquid stream.

[0148] Unless otherwise indicated, all numerical values ​​expressing quantities or properties of materials, such as molecular weights or reaction conditions, set forth and used in the specification and claims should be construed in all instances as being modified by the term "about." Accordingly, unless otherwise indicated, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. Each numerical parameter is not intended to limit the application of the doctrine of equivalents to the scope of each claim, but should at least be construed in light of the number of recited significant digits and ordinary rounding techniques. In cases where further clarity is needed, the term "about" when used in conjunction with a stated numerical value or numerical range has the meaning that a person of ordinary skill in the art would reasonably ascribe to it, i.e., in a range of ±20% of the stated numerical value; in a range of ±19% of the stated numerical value; in a range of ±18% of the stated numerical value; in a range of ±17% of the stated numerical value; in a range of ±16% of the stated numerical value; in a range of ±15% of the stated numerical value; in a range of ±14% of the stated numerical value; in a range of ±13% of the stated numerical value; in a range of ±12% of the stated numerical value; in a range of ±11% of the stated numerical value; in a range of ±10% of the stated numerical value; in a range of ±9% of the stated numerical value; in a range of ±8% of the stated numerical value; in a range of ±7% of the stated numerical value; in a range of ±6% of the stated numerical value; in a range of ±5% of the stated numerical value; in a range of ±4% of the stated numerical value; in a range of ±3% of the stated numerical value; in a range of ±2% of the stated numerical value; or in a range of ±1% of the stated numerical value.

[0149] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, any numerical value inherently contains certain errors necessarily resulting from the standard deviation in their respective testing measurements.

[0150] In the context of describing the present invention (particularly in the context of the claims below), the terms "a," "an," "the," and similar modifiers are to be construed as including both the singular and the plural, unless otherwise indicated or clearly contradicted by the context. Numerical ranges described herein are intended to be a shorthand way of referring to each numerical value falling within the range individually. Unless otherwise indicated, each numerical value is incorporated herein as if it were individually set forth herein. Any method described herein may be performed in any suitable order, unless otherwise indicated or clearly contradicted by the context. All examples and illustrative language (e.g., "etc.") provided herein are intended only to facilitate a more easily understood description of the present invention, and are not intended to limit the scope of the invention, which is not described in the claims. No language in the present specification should be construed as indicating any element essential to the practice of the invention, but not recited in the claims.

[0151] Combinations of alternative components or embodiments disclosed herein should not be construed as limitations. Each member of a combination may be referred to and claimed individually or in any combination with other members of the same combination or other components described herein. It will be understood that one or more members of a combination may be added to other combinations and one or more members may be deleted from a combination for ease of description and / or patentability. In the event of such addition or deletion, the specification shall be construed as including such modified combinations and shall satisfy the written description requirements for all Markush groups used in the appended claims.

[0152] Certain embodiments of the present invention are described herein, including what is, according to the inventors' knowledge, the best mode for carrying out the invention. Of course, variations of these above-described embodiments will become apparent to those of ordinary skill in the art upon reading the above description. The inventors anticipate that such variations will be employed by those of ordinary skill in the art, and the inventors intend that the invention may be practiced otherwise than as specifically described herein. Accordingly, the present invention is intended to include all modifications and equivalents of the invention as recited in the appended claims to the extent permitted by applicable law. Additionally, all combinations of the above-described elements in all possible variations thereof are encompassed by the present invention unless otherwise indicated or clearly contradicted by context.

[0153] Additionally, numerous references are made throughout this specification to patents, publications, journal articles, and other documents ("references" herein). Each reference is also individually incorporated herein by reference in its entirety for the teachings referenced thereto.

[0154] Finally, the embodiments of the invention disclosed herein should be construed as merely illustrative of the principles of the invention. Other variations that may be employed are within the scope of the invention. Thus, for example, but not by way of limitation, alternative configurations of the invention may be employed in accordance with the teachings set forth herein. Thus, the invention is not limited to that precisely as shown and described herein.

[0155] The specific examples presented in this disclosure are merely illustrative and are presented solely for the purpose of illustrating preferred embodiments of the present invention, and are presented in order to provide what is believed to be most useful for readily understanding the principles and conceptual aspects of various embodiments of the present invention. In this respect, structural details of the present invention have not been presented in more detail than is necessary for a fundamental understanding of the present invention, but it will be apparent to those skilled in the art, upon reading the description with reference to the drawings and / or examples, how some of the aspects of the present invention may be embodied in practice.

[0156] The definitions and explanations used in this disclosure are meant and intended to govern all future interpretations, unless they are clearly and unambiguously changed in each embodiment, or unless the application of the meaning would render the interpretation meaningless or substantially meaningless. If the interpretation of a term renders the term meaningless or substantially meaningless, the definition in a dictionary such as Webster's Dictionary (3rd Edition) or Oxford Dictionary of Biochemistry and Molecular Biology (Eds. Attwood T et al., Oxford University Press, Oxford, 2006), known to those skilled in the art, shall be adopted.

Claims

**Claim 1** A method for removing dissolved inorganic carbon from a carbon-containing liquid, comprising the step of exposing the carbon-containing liquid to a photoactive compound to remove the dissolved inorganic carbon from the carbon-containing liquid and transfer it to a second environment. **Claim 2** The method according to claim 1, wherein the photoactive compound is disposed in the carbon-containing liquid, disposed at a boundary in contact with the carbon-containing liquid, or disposed in a secondary fluid separated from the carbon-containing liquid. **Claim 3** The method according to claim 1, wherein the photoactive compound lowers the pH of the carbon-containing liquid. **Claim 4** The method according to claim 1, wherein the photoactive compound is an activated photoactive compound. **Claim 5** The method according to claim 1, wherein the photoactive compound comprises a reversible photoacid. **Claim 6** The method according to claim 1, further comprising the step of activating the photoactive compound by exposing the photoactive compound to light. **Claim 7** The method according to claim 1, wherein the photoactive compound is embedded in a material and / or coated on a surface of the material. **Claim 8** The method according to claim 2, wherein the material is disposed in the carbon-containing liquid, disposed in a boundary in contact with the carbon-containing liquid, or disposed in the secondary fluid. **Claim 9** The method according to claim 3, wherein the lowered pH is in the range of 2 to 7. **Claim 10** The method according to claim 1, further comprising the step of recovering the removed carbon. **Claim 11** The method according to claim 6, further comprising the step of deactivating the photoactive compound by stopping the exposure of the photoactive compound to light. **Claim 12** The method according to claim 2, further comprising the step of regenerating the photoactive compound by performing proton-cation substitution in the secondary fluid. **Claim 13** The method according to claim 2, wherein the protons transferred from the secondary fluid to the carbon-containing liquid are replaced with cations, anions are transferred to the carbon-containing liquid together with the protons transferred from the secondary fluid, and / or an electrochemical reaction is used to maintain the charge balance. **Claim 14** The method according to claim 1, wherein the dissolved inorganic carbon is carbon dioxide, carbonic acid, bicarbonate, and / or carbonate, the removed carbon is carbon dioxide, and / or the carbon-containing liquid is water. **Claim 15** ​ A duct for transferring the carbon-containing liquid to the photoactive compound, A light source for activating the photoactive compound, A system comprising a recovery unit for recovering the removed carbon, wherein the photoactive compound is embedded within a first material and / or coated on the surface of the first material, a system for implementing the method according to claim 1.

16. The system according to claim 15, further comprising a second duct for transferring a working fluid or a secondary fluid.

17. The system according to claim 15, further comprising a second material between the recovery unit and the target stream, the second material enabling the removed carbon to move from the recovery unit to the target stream.

18. The system according to claim 15, further comprising a solar power generation panel.

19. The system according to claim 18, wherein the solar power generation panel is disposed under the first material.

20. The system according to claim 15, further comprising a pump for flowing the carbon-containing liquid in the direction of the photoactive compound or a water head generated by a tidal current, a river, or a dam.

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