Alkaline cation enrichment and water electrolysis to provide co2 mineralization and global-scale carbon management

Abstract

To provide alkaline cation enrichment and water electrolysis to provide CO2 mineralization and global-scale carbon management.SOLUTION: Provided herein are methods of removing carbon dioxide from an aqueous stream or gaseous stream by: contacting the gaseous stream comprising carbon dioxide, when present, with an aqueous solution comprising ions capable of forming an insoluble carbonate salt; contacting the aqueous solution comprising carbon dioxide with an electro active mesh that induces its alkalinization thereby forcing precipitation of a carbonate solid from the solution and thereby removal of dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution, or a surface of the mesh where the carbonate solids may deposit. Also provided herein are flow-through electrolytic reactors comprising an intake device in fluid connection with a rotating cylinder comprising an electro active mesh, and a scraping device and / or liquid-spray based device for separating a solid from the mesh surface or solution.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 861,848, filed June 14, 2019, which is incorporated herein by reference.

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under Grant Nos. DE-FE0029825, DE-FE0031718, and DE-FE0031705 awarded by the U.S. Department of Energy. The federal government has certain rights in this invention. [Background technology]

[0003] To mitigate the rise in global average temperature and reduce the impacts of climate change, management of existing and ongoing atmospheric carbon dioxide emissions is required. To realistically achieve this, approximately 10-20 gigatonnes (Gt) of CO2 would need to be removed from the atmosphere per year within the next century, requiring carbon management plans that can be implemented on a large scale.

[0004] Relative carbon capture and storage is limited by handling CO2 in a fluid state (gas, liquid, supercritical, etc.), which creates constraints and complications for CO2 routes, processes, and disposal pathways, including expensive and energy-intensive separation, the significant energy required for compression, and the high cost of pressurized containment with the potential for leakage.

[0005] Injecting CO2 captured from point sources or the atmosphere into geological formations, including (depleted) oil and gas reservoirs, unminable coal seams, and saline aquifers, could sequester up to 22,000 Gt of CO2 in North America. While the theoretical capacity is enormous, in practice, pressure limitations necessary to prevent rock fracturing or reactivation of existing faults, and / or the presence of residual hydrocarbons, result in a more modest storage capacity of approximately 700 Mt per year over 50 years of injection. While the potential capacity of geological sequestration is expected to be more than adequate to accommodate current (and future) levels of CO2 emissions, the risks of CO2 migration and leakage, as well as the management and verification of the injection process, require significant monitoring of wells, underground, and at the surface over time. Furthermore, conventional approaches to carbon management based on carbon capture, sequestration, and storage (CCSS) are constrained by (i) the need to satisfy the thermodynamic penalty associated with the entropy of demixing CO from either air or flue gas streams and the subsequent enthalpy of desorption of CO from solid or liquid substrates, and (ii) the need for significant logistical and transportation infrastructure (e.g., pipelines) to transport CO to geological sequestration. In particular, in conventional absorption / desorption CO capture, energy consumption is associated with the separation of CO from the gas mixture, which involves a reduction in the entropy of the system, and the desorption step, which allows CO to be concentrated to a grade sufficient for pipeline transport and subsequent geological sequestration. In summary, while technical challenges remain and are being gradually resolved, the practical realization of CCSS relies heavily on policies around the world that empower CCSS project developers and support them in risk mitigation, within limits, best practices, and time-bound monitoring, to do no harm.

[0006] Beyond geological sequestration and storage, changes in land use, agricultural practices, marine geoengineering, and chemical conversion of CO2 into building materials represent alternative, large-scale pathways that comprise a portfolio of approaches to ensure carbon management (e.g., emissions reductions and atmospheric carbon removal). While some progress has been made in developing negative (CO2 / carbon) emission technologies (NETs), much greater "exponential" progress is needed to achieve the necessary CO2 removal rates and durable carbon storage in a cost-effective / cost-feasible manner.

[0007] It is against this background that the embodiments described in this disclosure became necessary to be developed. Summary of the Invention [Means for solving the problem]

[0008] Some embodiments of the present disclosure include a method for removing carbon dioxide from a water or gas stream by contacting the gas stream containing carbon dioxide with an aqueous solution containing ions capable of forming insoluble carbonate salts, if present; contacting the aqueous solution containing carbon dioxide with an electroactive mesh that induces alkalization of the aqueous solution containing carbon dioxide, thereby precipitating carbonate solid(s) from the solution; and removing the precipitated carbonate solids from the solution or from the surface of the mesh on which the carbonate solids may be deposited. In some embodiments, the gas stream is present. In some embodiments, the gas stream contains 0.04-100% CO2 by volume. In some embodiments, the gaseous fluid is atmospheric air. In some embodiments, the gaseous fluid is flue gas emitted from natural gas-fired power plants, coal-fired power plants, iron and steel mills, cement plants, ethanol plants, and chemical manufacturing plants. In some embodiments, the aqueous solution contains an amount of dissolved carbon dioxide in equilibrium with the gas stream. In some embodiments, the aqueous solution is in thermal equilibrium with the gas stream. In some embodiments, the aqueous solution is not in thermal equilibrium with the gas stream. In some embodiments, the gas stream is absent. In some embodiments, the ions capable of forming insoluble carbonates include ions including one or more of Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, and Al. In some embodiments, the aqueous solution has a NaCl concentration of about 1,000 ppm or greater. In some embodiments, the aqueous solution has a NaCl concentration of about 30,000 ppm or greater. In some embodiments, the aqueous solution comprises seawater. In some embodiments, the electroactive mesh comprises a mesh cathode comprising a metal or non-metallic composition. In some embodiments, the method utilizes an end-to-end energy intensity of about 2.5 MWh or less per ton of mineralized carbon dioxide. In some embodiments, the aqueous solution contains dissolved carbon dioxide in an amount that buffers it from atmospheric abundance.In some embodiments, the electroactive mesh enhances alkaline conditions in situ in the aqueous solution within about 2-20,000 μm of the electroactive mesh. In some embodiments, the alkalized condition is a pH of 9 or greater. In some embodiments, the electroactive mesh comprises a metal mesh or a carbon-based mesh. In some embodiments, the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions of these materials. In some embodiments, the electroactive mesh comprises pores with diameters ranging from about 0.1 μm to about 10,000 μm. In some embodiments, inducing precipitation of carbonate solids comprises rotating a cylinder of the mesh in the solution while applying a suction force to draw the solution onto the exterior surface of the electroactive mesh. In some embodiments, the solution is a brine solution. In some embodiments, the solution is an alkaline metal-containing solution. In some embodiments, inducing precipitation of the carbonate solids comprises inducing precipitation of at least one carbonate having Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, or Al.

[0009] Some embodiments of the present disclosure include a flow-through electrolytic reactor comprising an entrainment device fluidly connected to a rotating cylinder comprising an electroactive mesh, and a scraping device and / or liquid spray-based device for separating solids from a surface or solution. In some embodiments, the reactor further comprises an aqueous solution comprising carbon dioxide, Ca ions, and Mg ions. In some embodiments, the electroactive mesh can induce dissolved inorganic carbon removal by precipitation of carbonate solids from an aqueous solution comprising carbon dioxide and ions capable of forming insoluble carbonates. In some embodiments, the electroactive mesh comprises a metal mesh or a carbon-based mesh. In some embodiments, the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions of these materials. In some embodiments, the reactor comprises a plurality of electroactive meshes. In some embodiments, the plurality of electroactive meshes are arranged in a series of parallel planar cells or parallel cylindrical cells. In some embodiments, the reactor is in fluid communication with a desalination device. [Brief explanation of the drawings]

[0010] [Figure 1] 1 illustrates an embodiment of a carbon dioxide mineralization and treatment process. The heating element and diffuser are optional components. [Figure 2](a) Representative calculation showing the limits of calcite precipitation as affected by Ca, CO2, or alkalinity for a solution with the composition [Ca] = 10 mM, [Cl] = 20 mM, [CO2] = 10 mM (approximately 30% CO2; 300,000 ppm), and pH = 4.16 (dotted curve). The maximum yield of CaCO3 is 10 mmol per kg of water. As [Ca] is reduced to 3 or 5 mM (dark blue curve) ([Cl] is either 6 or 10 mM, [CO2] = 10 mM, pH = 4.17), the maximum yield of CaCO3 drops to 3 and 5 mmol. Similarly, reducing [CO2] to 3 mM (light blue curve) (approximately 9% CO2, pH = 4.42) or 5 mM (approximately 15% CO2, pH = 4.31) ([Ca] = 10 mM, [Cl] = 20 mM) reduces the maximum yield of CaCO3. Interestingly, reducing [Ca] increases NaOH consumption at equivalent CaCO3 yields, while reducing [CO2] reduces NaOH consumption. (b) Compares two scenarios: (i) an initial pCO2 of 5%, corresponding to 1.73 mM CO2 (thick curve), decreases with precipitation; and (ii) the solution pCO2 is kept constant at 5% (e.g., by continuous equilibration with a CO2 gas flow (17,300 ppm)) (thin curve). In (i), CaCO3 precipitation is rapidly induced by the addition of NaOH and, similar to (a), is limited by total dissolved CO2. A continuous supply of CO2 in (ii) allows precipitation of CaCO3 with a yield of approximately 7 mM (limited by [Ca]). (c) shows the NaOH consumption for calcite precipitation for solutions in equilibrium with CO2 at various pCO2 levels (vol %), as determined by Henry's law. [Figure 3] Figure 1 shows the total dissolved carbon content as a function of pH for solutions in equilibrium with a gas stream of CO2 over a range of different gas-phase concentrations. Total dissolved CO2 is equal to [H2CO3 *] + [HCO3 -] + [CO3 2-]. For reference, 0.04% represents the CO2 concentration in air. The CO2 content in air is shown for comparison. [Figure 4]Representative equilibrium calculations using PHREEQC and the llnl.dat database of reference seawater compositions, as reported by Millero et al. (Deep Sea Research Part I: Oceanographic Research Papers 2008 55 (1), 50-72). Calcite and magnesite precipitate by simultaneous addition of CO2 and NaOH in a 1:2 molar ratio, with magnesite at a maximum of approximately 55 mmol per kg of water and calcite at approximately 10 mmol per kg of water. The saturation concentration of CO2 at atmospheric pressure is approximately 34 mM. In an engineered process, CO2 equilibrium can be maintained simply by bubbling air through the carbonate precipitation process (see Figure 2(b) and (c)). [Figure 5]Figure 1 shows the energy requirement for CO2 capture and compression as a function of concentration (red solid curve) for an amine-based process simulated using Aspen Plus®. The thermodynamic minimum energy required for CO2 separation from the mixture and compression from 1 atmosphere to 15 MPa (red dotted curve) is calculated based on the entropy of (de)mixing of gas-phase CO2. Also shown are the energy costs of CO2 mineralization (blue solid curve) and chloralkali generation of NaOH (blue dashed curve) at the thermodynamic minimum energy requirement for production. The theoretical energy requirement for producing NaOH from NaCl is taken from Thiel et al. (ACS Sustainable Chem. Eng. 2017, 5(12), 11147-11162). Energy costs for direct air capture and compression (DACC) using the KOH / K2CO3 process (magenta triangles) and the integrated caustic-amine process (green circles) are taken from Keith et al. (Joule 2018, 2(8), 1573-1594, and Climatic Change 2006, 74(1), 17-45). The vertical grey lines represent CO2 concentrations in air, natural gas-fired and coal-fired power plants, and the flue gas of a cement plant. The shaded areas represent a representative range of energy costs for the following CO2 abatement methods: (red) capture and compression (range: 0.1 MWh, thermodynamic minimum to 4.5 MWh per tonne of CO2; depending on concentration); (blue) stoichiometric addition of electrolytically synthesized NaOH (range: 1.26 MWh (thermodynamic minimum) to 4.5 MWh per tonne of CO2); and (yellow) electrolytic precipitation approach (single-step carbon sequestration and storage) (range: 0.07 MWh (thermodynamic minimum) to 2.3 MWh per tonne of CO2; independent of concentration). [Figure 6](a) Schematic diagram of localized OH generation on the membrane cathode (b) as a means of inducing carbonate precipitation. Agglomerates deposited on or near the membrane surface are removed using a rotating drum filtration solution. (c) Electrolyte pH after 1 second of electric polarization for various overpotentials, simulated using COMSOL Multiphysics® with adaptive time-stepping, triangular mesh elements (mesh opening area 173.21 μm²), and periodic boundary conditions. The water decomposition potential is assumed to be 0 V RHE (RHE: Reversible Hydrogen Electrode) (see RSC Adv. 2019, 9(54), 31563-31571). The simulations considered a planar electrode (100 mm) made of 304L stainless steel immersed in excess electrolyte (0.1 M NaCl). For the hydrogen evolution reaction (HER), the Tafel relationship [η = 0.172 + log(i / i), where η is the overpotential (V), i is the current density (A / m), and i is the exchange current density (1.04 × 10 A / m)] yields pH(t) = 14 + log[{(10[(η −1.2) / 0.172])t} / 9.6485 + 10], where pH is the average pH of the adjacent salt-containing electrolyte within a 1 mm-thick region, η is the overpotential (V), and t is time (s). For example, an overpotential of approximately 0.5 V is required to produce a pH of 10 at the membrane surface, at which all inorganic carbon in solution is speciated in the form of CO anions. As expected, increasing the surface area of ​​the electrode (e.g., by using a mesh) or improving the electrochemical activity of the electrode reduces the overpotential required to induce alkalinization near the surface. [Figure 7] FIG. 1 shows a single-step carbon sequestration and storage concept to achieve CO mineralization and processing. [Figure 8](a) Cathodic polarization curve of 304L stainless steel in 0.1 M NaCl solution. The dashed line represents the Tafel approximation of the hydrogen evolution reaction (HER), i.e., [η = 0.172 + log(i / i0) (where η is the overpotential (V), i is the current density (A / m2), and i0 is the exchange current density (1.04 × 10-7 A / m2)], which indicates that pH(t) = 14 + log[{(10[(η-1.2) / 0.172])t} / 9.6485 + 10-7] in the electrolyte within a 1 mm-thick region at time t (s). (b) shows the simulated equilibrium pH between the anode and cathode as a function of overpotential (e.g., 1.23 V, the difference between the cell potential and the water decomposition potential) in the annular reactor (inset). The pH is controlled by the production and mass transfer of OH- and H+ ions and acid-base neutralization (OH- + H+ → H2O). [Figure 9] (a) shows a cross-sectional view of an electro-precipitation apparatus having a planar geometry. (b) shows a cross-sectional view of an electro-precipitation apparatus having a cylindrical geometry. In both configurations, acidified (C, Ca, Mg) depleted seawater outlet feed can be used for silicate weathering, which increases the alkalinity and pH of the effluent. [Figure 10] (a) shows a 1 mm thick mesh geometry with cylindrical pores (100 μm radius) simulated using COMSOL Multiphysics®, e.g., a cross section of the cathode in FIG. 10(b), (b) shows the pH of the solution in the pores at various current densities at a flow rate of 1 mm / s, and (c) shows the pH of the solution in the pores at various average flow rates at a current density of 1 mA / cm. [Figure 11](a) Carbon nanotube-polyvinyl alcohol (CNT-PVA) composite membrane showing surface morphology and pore size of approximately 125 nm. (b) Optical microscope image (approximately 1 mm × 1 mm field of view (FOV)) of the anode activated carbon (graphite) electrode surface (pore size 20 μm) after exposure to 10 mM CaCl solution and application of a potential of 1 V (battery) in a flow reactor, showing a precipitate identified as CaCO by thermogravimetric analysis. Removal of dissolved Ca was further evidenced by the lower [Ca] at the outlet compared to the inlet. DETAILED DESCRIPTION OF THE INVENTION

[0011] Certain embodiments of the present disclosure relate to methods for fixing CO2.

[0012] In one aspect of some embodiments, a method includes introducing carbon dioxide into a solution and inducing precipitation of carbonate solids from the solution, wherein inducing precipitation of the carbonate solids includes subjecting the solution to water electrolysis. In some embodiments, introducing carbon dioxide into the solution is via a gas diffuser. In some embodiments, the solution contains (dissolved) carbon dioxide due to equilibration with the atmosphere. In some embodiments, subjecting the solution to water electrolysis includes increasing the pH of the feed solution. In some embodiments, subjecting the solution to water electrolysis includes generating hydroxide ions. In some embodiments, inducing precipitation of the carbonate solids includes rotating the membrane drum in the solution while applying suction to draw the solution onto the surface of the membrane drum. In some embodiments, the solution is a brine solution. In some embodiments, the solution is an alkaline metal-containing solution. In some embodiments, inducing precipitation of the carbonate solids includes inducing precipitation of at least one of calcium carbonate or magnesium carbonate, or other carbonates (e.g., barium carbonate) or other related solids. In some embodiments, the method further includes concentrating alkaline metal cations in the solution.

[0013] In another aspect according to some embodiments, a method includes introducing carbon dioxide into a solution and inducing precipitation of carbonate solids from the solution, wherein inducing precipitation of the carbonate solids includes rotating the membrane drum in the solution while applying suction to draw the solution onto the surface of the membrane drum. In some embodiments, introducing carbon dioxide into the solution is via a gas diffuser. In some embodiments, inducing precipitation of the carbonate solids includes performing water electrolysis on the solution. In some embodiments, performing water electrolysis on the solution includes increasing the pH of the feed solution. In some embodiments, performing water electrolysis on the solution includes generating hydroxide ions. In some embodiments, the solution is a brine solution. In some embodiments, the solution is an alkaline metal-containing solution. In some embodiments, inducing precipitation of the carbonate solids includes inducing precipitation of at least one of calcium carbonate or magnesium carbonate, or other carbonates (e.g., barium carbonate) or other related solids. In some embodiments, the method further includes concentrating alkaline metal cations in the solution.

[0014] In another aspect of some embodiments, a method for removing carbon dioxide from a water or gas stream is provided by contacting the gas stream containing carbon dioxide with an aqueous solution containing ions capable of forming insoluble carbonate salts, if present; contacting the aqueous solution containing carbon dioxide with an electroactive mesh that induces alkalinization of the aqueous solution, thereby precipitating carbonate solids from the solution and removing dissolved inorganic carbon by electrolysis; and removing the precipitated carbonate solids from the solution or from the surface of the mesh on which the carbonate solids may be deposited. In some embodiments, the gas stream is present. In some embodiments, the gas stream contains about 0.04-100% CO by volume (e.g., about 0.04, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 98, 99, 99.9% CO by volume, and ranges therebetween). In some embodiments, the gas stream is atmospheric air. In some embodiments, the gaseous fluid is flue gas emitted from natural gas and coal-fired power plants, iron and steel mills, cement plants, ethanol plants, and chemical production plants, among others. In some embodiments, the aqueous solution contains an amount of dissolved carbon dioxide in equilibrium with the gas stream. In some embodiments, the aqueous solution is in thermal equilibrium with the gas stream, e.g., at a temperature of 5°C < T < 100°C. In some embodiments, the aqueous solution is not in thermal equilibrium with the gas stream, e.g., at a temperature of 5°C < T < 100°C. In some embodiments, the gas stream is absent. In some embodiments, the ions capable of forming insoluble carbonates include ions including one or more of Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, and Al. In some embodiments, the concentration of NaCl in the aqueous solution is about 1,000 ppm or greater. In some embodiments, the concentration of NaCl in the aqueous solution is about 30,000 ppm or greater.In some embodiments, the aqueous solution has a NaCl concentration of about 1,000, 2,000, 3,000, 4,000, 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000 ppm, and ranges therebetween. In some embodiments, the aqueous solution comprises seawater, brackish water, or brine. In some embodiments, the electroactive mesh comprises a mesh cathode comprising a metal or non-metallic composition. In some embodiments, the method utilizes an end-to-end energy intensity of about 2.5 MWh or less per ton of mineralized carbon dioxide. In some embodiments, the aqueous solution contains dissolved carbon dioxide in an amount that buffers it to atmospheric abundance. In some embodiments, the electroactive mesh enhances alkaline conditions in situ in the aqueous solution within about 2-20,000 μm of the electroactive mesh. In some embodiments, the alkalinized condition is a pH of 9 or greater (e.g., a pH of about 9, 10, 11, 12, 13, 14, and ranges therebetween). In some embodiments, the electroactive mesh comprises a metal mesh or a carbon-based mesh. In some embodiments, the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions of these materials (e.g., metal / polymer, metal / non-metal, metal / ceramic). In some embodiments, the electroactive mesh comprises pores ranging in size from about 0.1 μm to about 10,000 μm (e.g., about 10, 50, 100, 200, 300, 400, 500, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10,000 μm). In some embodiments, inducing precipitation of the carbonate solids comprises rotating a cylinder of the electroactive mesh in the solution while applying a suction force to draw the solution onto the exterior surface of the electroactive mesh, hi some embodiments, the solution is an alkaline metal-containing solution.In some embodiments, inducing precipitation of the carbonate solids comprises inducing precipitation of at least one carbonate having Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, and Al.

[0015] In another aspect according to some embodiments, a flow-through electrolysis reactor comprises an entrainment device fluidly connected to a rotating cylinder comprising an electroactive mesh, and a scraping device and / or a liquid spray-based device for separating solids from the mesh surface / solution. In some embodiments, the flow-through electrolysis reactor further comprises an aqueous solution comprising carbon dioxide, Ca ions, and Mg ions. In some embodiments, the electroactive mesh can induce dissolved inorganic carbon removal by precipitation of carbonate solids from an aqueous solution comprising carbon dioxide and ions capable of forming insoluble carbonates. In some embodiments, the electroactive mesh comprises a metal mesh or a carbon-based mesh. In some embodiments, the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions. In some embodiments, the reactor comprises a plurality of electroactive meshes. In some embodiments, the plurality of electroactive meshes are arranged in a series of parallel planar cells or parallel cylindrical cells. In some embodiments, the reactor is in fluid communication with a desalination device.

[0016] CO2 can be immobilized in stable mineral carbonates. The basis of the above scheme is the synthesis of gaseous CO2 and Ca2+ in aqueous media, from liquid and solid streams. 2+ and / or Mg 2+The precipitation of solid calcium carbonate (CaCO3), magnesium carbonate (MgCO3), and their variants results from the combination of carbon dioxide with ions (or other ions capable of forming insoluble carbonates, such as Ba, Sr, Fe, and Zn). The mineralized carbon is then disposed of on the Earth's surface or discharged into the ocean. The large carbon storage capacity, minimal environmental impact, and low risk of CO2 release after capture support the scheme's viability as a primary pathway for long-term gigatonne-per-year (Gt-scale) CO2 waste management.

[0017] The basic CO2 mineralization process can be achieved by adding a strong base, such as NaOH, to a near-neutral Ca- and Mg-containing feed solution (e.g., purified water containing about 10 millimolar (mM) CaCl2 and about 55 mM MgCl2), similar to seawater, as described below. The feed solution may also consist of liquid streams such as alkaline metal-rich groundwater, industrial wastewater, or brines resulting from desalination. Alkaline cation concentration constitutes an optional pretreatment step to increase the concentration of Ca, Mg, and other alkaline cations in the water. Concentration can be achieved by filtration, volumetric concentration, or a combination thereof. Effective mixing and CO2 equilibration can then be achieved using an aeration tank, such as those used in activated sludge processes in wastewater treatment, to produce CO2-enriched water. The CO2-enriched water can then be combined with a base (e.g., NaOH), such as those used in coagulation and flocculation processes for water treatment, resulting in the precipitation of CaCO3 and MgCO3. The precipitate can be separated by settling and the discharged solids can either be further dewatered and landfilled or discharged into the ocean, similar to brine treatment in a desalination plant.

[0018] The thermodynamics and kinetics of carbonate mineralization can be further enhanced by local pH and temperature changes induced on the membrane surface. In an advanced CO2 mineralization process, hydroxide ions (OH) are produced by electrolysis of water (via a water electrolyzer) instead of adding consumable reactants. -The system includes a carbon dioxide mineralization and treatment system that generates OH from the electrolysis of water and increases the temperature of the area (via a heating element). A more basic solution increases the driving force for carbonate precipitation, and the electrolysis of water increases the driving force for OH. - The formation of CO₂ increases the pH of the liquid, promoting carbonate precipitation. Similarly, higher temperatures increase the driving force for carbonate precipitation, and the use of heating elements increases the temperature of the liquid to promote carbonate precipitation. CO₂ may be optionally injected or otherwise introduced into the liquid via a gas diffuser and compressor, or may be present in the liquid at a level in equilibrium with its gas atmosphere. As shown in Figure 1, the design of the apparatus is in the form of a rotating vacuum membrane drum located within a tank and rotating in the CO₂-rich, Ca / Mg-containing liquid (e.g., seawater or other brine solution). The membrane drum comprises a membrane (e.g., a metal membrane in the form of a mesh or sieve) as a filtration medium surrounding a central duct through which suction (i.e., negative pressure) is applied. As the membrane drum rotates through the liquid, carbonates may form on the surface of the membrane. A vacuum pump is connected to the central duct, applying suction to draw the liquid onto and through the membrane surface, removing Ca at the membrane surface. 2+ and Mg 2+ CO3 2- The filtrate, now with reduced Ca / Mg concentrations, flows inside the membrane drum and is pumped out. The carbonate solids adhere to the outside of the membrane drum, which then passes through knives that remove the solids from the membrane, thereby regenerating the membrane surface for subsequent carbonation as the drum rotates back into the liquid. This advanced process also has the potential for process integration with / in desalination plants, which would address the climate change issues of CO2 and the scaling issues in membrane desalination plants (Ca deposition on the membrane surface). 2+ and Mg 2+ This simultaneously addresses the problems caused by the accumulation of compounds. [Example]

[0019] The precipitation of calcium carbonate, e.g., calcite, is given by: CaCO3 (calcite) ⇔ Ca 2+ +CO3 2- , logK sp =-8.48(25℃)[1] In the formula, K sp is the solubility product (also known as the equilibrium constant), and Ca 2+ and CO3 2- In the precipitation of calcite, HCO3 - or CO3 2- (both formed by CO2 speciation in water) can be adsorbed and incorporated onto the growing surface. sp decreases with temperature, so that raising the temperature of a calcite-saturated solution from 25°C to 90°C results in the precipitation of calcite at a yield of approximately 300 μmol / kg-water. The species formation reaction and dissociation constants for the CO2-H2O system are written as follows: [ka] In the formula, H2CO3 * CO2 (aqueous solution) and H2CO3 0 The distribution of dissolved CO2 is shown by the Bjerrum diagram. Generally, CO3 2- The activity of the anion is pH dependent (e.g., in water, above pH 10.33, CO3 2- is the dominant carbon species), and the degree of calcite precipitation is similar. At higher salinity, K1 and K2 shift to larger values, so HCO3 - and CO3 2- The pH in the ion-dominated state shifts to lower values. The thermodynamic driving force for mineral precipitation is the saturation ratio Ω = IAP / K. sp where IAP is the ionic activity product. For example, for calcite, the ionic activity product is the amount of Ca in solution. 2+ and CO3 2-This is relevant to common natural waters (e.g., groundwater, seawater, produced waters) that contain divalent metal cations because their near-neutral pH requires supplemental alkalinity to induce carbonate precipitation. Because Ca and Mg are the most abundant divalent cations in natural waters and often industrial waters (e.g., produced waters, thermally evaporated brines, etc.), these waters are expressed as CaCl2 solutions, which are primarily composed of Cl. - This is because the charge compensation is relative to the cations in these systems.

[0020] Addition of NaOH changes the pH and Ω of the solution. カルサイト The pH rises, eventually resulting in the precipitation of calcite. For a solution with a fixed initial CO2 concentration (pCO2), calcite precipitation is limited by either the amount of Ca, CO2, or alkalinity (pH). These scenarios are illustrated in Figure 2(a), which considers CO2-added CaCl2 solutions with various Ca, CO2, or alkalinity concentrations. In less acidic solutions (e.g., lower CO2 concentrations), less NaOH is required to initiate calcite precipitation, but the maximum CaCO3 yield (limited by CO2 in this scenario) may be correspondingly lower (light blue curve in Figure 2(a)). On the other hand, when excess CO2 is present in solution, Ca may become the limiting reactant. The case where both the NaOH:CaCO3 and H2O:CaCO3 molar ratios are minimized is when the molar concentrations of Ca and CO2 are approximately equal and NaOH (representing alkalinity) is added until the maximum CaCO3 yield is reached (dotted line in Figure 2(a)). + and CO3 2- forms a complex, and therefore the molar ratio between CO2 and Ca is {CO3 2-} and {Ca 2+} (where the brackets {} denote activity), is reached, resulting in an equivalence slightly higher than 1. The molar ratio between the NaOH consumed and the CO2 sequestered as CaCO3 is at least 2 (e.g., this is equivalent to 1 mole of OH for each of reactions [2] and [3]).- (Provide).

[0021] For liquid streams characterized by low CO2 concentrations, air may be bubbled through the aqueous feed depending on the CO2 consumption rate. To illustrate this, two scenarios are compared in Figure 2(b): one in which the initial CO2 concentration is fixed and dissolved carbon is gradually depleted, and one in which the solution CO2 concentration is maintained constant by equilibration with a gas stream characterized by a fixed pCO2. In the first case, CaCO3 precipitation is rapidly induced by the addition of NaOH and is limited by total dissolved CO2, while in the second case, CO2 replenishment allows calcite precipitation until Ca is depleted. In the second scenario, precipitation is initially inhibited due to excess acidity, e.g., CO2. For completeness, various scenarios of CO2 equilibration / replenishment for various pCO2 levels are shown in Figure 2(c). In the limit, carbonate yield depends only on the amount of [Ca] present in the feed and is invariant with CO2 concentration. The amount of CO2 that can be dissolved in water is controlled by Henry's law constant, which depends on its pH, salinity, and temperature. For a given solution, increasing the pH of the solution (pH > 6) increases the total dissolved carbon (Figure 3). This is because the ratio of CO2 (in water) to HCO3 - and CO3 2- This is due to pH-dependent speciation into CO2 (soluble in water), which reduces the concentration of CO2 (gas), allowing more CO2 (gas) to dissolve, according to Henry's law. At pH above 6, the formation of cation-carbonate and cation-bicarbonate complexes in seawater increases the carbon storage capacity of seawater compared to freshwater.

[0022] The carbonate precipitation reaction is characterized by a time scale. Under well-mixed conditions (i.e., no mass transfer limitations) at 25°C and 1 atm, the equilibrium described by the reaction [4] is t = 5.0 × 10 -11 Occurs within seconds. CO2 (gas) ⇔ CO2 (water-soluble) [4] The aqueous species H2CO3, HCO3 are described by reactions [5]-[7] - , and CO3 2- is 10 -2 Equilibrium is reached within seconds. CO2 (water soluble) + H2O⇔H2CO3[5] H2CO3⇔H + +HCO3 - [6] HCO3 - ⇔H + +CO3 2- [7] However, Ca 2+ The equilibrium for (i.e., reactions [8] and [9]) is 10 3 It takes a few seconds to reach it. Ca 2+ +CO3 2- ⇔CaCO3 (water soluble) [8] CaCO3 (water soluble) ⇔ CaCO3 (solid) [9]

[0023] In alkaline solutions (pH > 10), HCO3 - Forming OH - An alternative route for the solvation of CO2 by reaction with H2O (K = 6.6 × 10 -4 M -1 s -1 ) is even faster than (K=8.5×10 3 M -1 s -1 The precipitation rate of calcite in concentrated solutions similar to seawater (over 0.5M NaCl) is 3.2 × 10 6 Ms -1 The precipitation rate constant is about 100 kJ / s, and the yield is consistent with that shown in Figure 2(c). This rate constant is R = k(Ω-1) n Formula of the form (where R is in units of M s -1 The settling velocity, k, is in M ​​s -1 where Ω is the rate constant for calcite, and n is the reaction order. ) is derived by fitting experimental (calcite precipitation) data. Therefore, in a well-mixed system with low mass transfer resistance, Ca 2+The reaction with CO₂, e.g., precipitation of CaCO₃, is rate-limiting. This allows for the analysis of the mass and energy balance for future CO₂ mineralization.

[0024] Establishing a Baseline: In general, the above analysis indicates that alkalinity promotes carbonate precipitation. Therefore, we first considered the common approach of adding a strong base, such as NaOH, to a near-neutral Ca- and Mg-containing solution (Figure 4). For reference, note that CO2 concentrations in point-source emissions are approximately 3% (volume %) for natural gas-fired power plants, 15% for coal-fired power plants and iron and steel mills, 20% for cement plants, and over 90% for ammonia, ethanol, and hydrogen plants. Meanwhile, atmospheric CO2 concentrations are approximately 0.04%, while the purity of CO2 captured by amine scrubbing can be greater than 99%. Therefore, this analysis includes standard concentrations of 0.04%, 5%, 20%, and 100%. The CO2 mineralization assumed in the baseline case is modeled using a water treatment process analogy. First, when using a CO2 source other than air, an aeration tank similar to those used in activated sludge processes can be used to facilitate effective mixing with the brine and CO2 equilibration. NaOH can then be mixed with the CO2-rich water to precipitate CaCO3 and MgCO3, similar to coagulation and flocculation processes. The precipitate is then separated from the solution by settling, and the discharged solids can be dewatered using a belt press or discharged into the ocean, similar to brine treatment in desalination.

[0025] Ensuring Calcium and Magnesium Sufficiency for Carbonate Mineralization Ca and Mg are available in more than sufficient quantities to meet the demands of global carbon management. For example, removing 10 Gt of CO2 per year would require 9.1 Gt of Ca or 5.5 Gt of Mg, which represents 0.0017% of the total Ca and 0.00032% of the total Mg in the world's oceans ("seawater"). Alternatively, although at significantly lower levels, calcium and magnesium are also present in (a) saline groundwaters that may contain more than 1,000 mg total dissolved solids (TDS) per liter, with withdrawal rates of 3.2 billion m3 / year in 2015; 3 (b) above saline groundwater, which amounts to 0.6 Mt of Ca and 0.3 Mt of Mg (using typical Ca and Mg concentrations in brackish water in the United States); and (b) 50 billion m per year. 3 These can be sourced from (a) brines from desalination, which are produced globally at a rate of 1.2 Gt / year and could provide an additional 0.04 Gt of Ca and 0.1 Gt of Mg per year, and (b) produced waters with a production of 2.23 Gt / year, which, assuming an average Ca concentration of 5,000 mg / liter, could provide an additional 0.01 Gt of Ca per year in the United States alone. Alkaline by-products from metal, alloy, and cement manufacturing and coal combustion are rich in Ca and Mg, but their weathering is also hypothesized to sequester more than 0.3 Gt of CO2 per year. Nevertheless, seawater remains the most viable and abundant source of divalent metal ions for mineralization processes.

[0026] From stoichiometry, 2 moles of NaOH are required to convert 1 mole of CO2 to 1 mole of CaCO3 (see Figure 2(a) and Figure 4). Therefore, mineralization of 10 Gt of CO2 requires at least about 18 Gt of NaOH. However, the global production of NaOH is relatively small, at around 70 Mt in 2016. However, based simply on the Na content of NaOH, if seawater is used, it is estimated that 3.2 x 10 7It is also possible to synthesize 10 Gt of NaOH per year. Meeting this demand would require 6,000 large-scale chloralkali plants, each producing 3 Mt of NaOH per year, an impractical task. By dosing seawater ([Mg] ≈ 55 mM, [Ca] ≈ 10 mM) with enough NaOH, 2.86 g of CO2 per kg of water could be converted to MgCO3 and CaCO3 (Figure 4). Therefore, to sequester 10 Gt of CO2 per year, approximately 3,500 Gt of water would need to be treated per year, an amount similar to the world's annual water withdrawals (approximately 4,000 Gt). Meanwhile, over 14,700 treatment plants in the United States treat 47 Gt of wastewater per year. If a single CO2 reduction facility were to treat 2,000 Mt of seawater per year (e.g., the size of a large wastewater treatment plant), 1,760 such plants would need to be built worldwide, each supplied with 10 Mt of NaOH per year. Because carbonate yield is limited by the content of divalent cations in the feed, increasing the Ca and Mg concentration in the feed stream (e.g., using a membrane that can selectively separate divalent cations) would allow for the treatment of smaller volumes of water. Such pretreatment, despite the resulting increase in carbonate yield, can only be carried out while incurring a substantial energy penalty that would apparently be unfeasible.

[0027] Energy Intensity Analysis: The energy requirements of a mineralization process using seawater as the source of divalent cations and NaOH as the stoichiometric additive can be estimated for comparison with the geological CCSS scheme. Unlike the geological CCSS, CO2 reductions based on seawater mineralization do not require a CO2 capture step. Therefore, the energy requirements of the baseline process (although practically infeasible) are based on the need for water handling and treatment, as well as NaOH production. Water handling and treatment include (a) seawater intake, which requires approximately 1.3 kWh per ton of mineralized CO2; (b) chemical dispersion, which requires 2.8–7.7 kWh per ton of mineralized CO2; and (c) sedimentation, which requires 0.175–0.35 kWh per ton of mineralized CO2. Therefore, assuming a seawater supply, water treatment and handling could consume a total of approximately 5 kWh per ton of mineralized CO2. Synthesis of NaOH by the chlor-alkali process requires 2.5 MWh per ton of NaOH. Therefore, the energy requirement for direct CO2 mineralization (using seawater as a source of both divalent ions and (solubilized) CO2) is estimated to be around 4.5 MWh per ton of CO2 (Figure 5). The estimated cost of CO2 removal, based on industrial electricity rates of about $70 per MWh, is therefore $315 per ton of CO2 for current best-in-class chloralkali-produced NaOH. The cost of introducing alkaline metals (Ca) into solution by dissolving them, e.g., alkaline solids, is $100 per ton of CO2. 2+ , Mg 2+ ) and OH -The need for NaOH can be somewhat reduced by carbonating the alkaline solids produced by CO2 extraction. The energy input for such direct carbonation, including pretreatment costs such as grinding and possibly thermal activation, disposal of the (carbonate) product, and running pumps and mixers, is approximately 0.5 MWh per ton of CO2. Unfortunately, direct carbonation of such industrial alkaline solids is expected to result in CO2 reductions of less than 0.3 Gt per year. A somewhat less energy-intensive NaOH production route may be realized through bipolar membrane electrodialysis. Even if it were possible to produce NaOH (45% NaOH and HCl, a by-product that can be used to improve silicate dissolution) with its theoretical minimum energy requirement of 0.7 MWh per ton of NaOH, the cost of mineralization-based CO2 management would involve an energy intensity of at least 1.26 MWh per ton of CO2 (blue dashed horizontal line in Figure 5), which corresponds to a cost of more than $90 per ton of CO2 converted to solid carbonate using, for example, divalent cations from seawater.

[0028] Energy intensities of conventional CCSS pathways are calculated using Aspen, including the eRNTL thermodynamic properties method. This is estimated by considering a monoethanolamine (MEA)-based process using the Catalyst Plus®, consisting of an absorber, stripper, cooler, and a four-stage compressor (see Figure 5). It was assumed herein that CO2-depleted gas is withdrawn from the top of the absorber, while a CO2-rich solvent stream is withdrawn from the bottom. To release the CO2, the CO2-rich amine is heated to satisfy the enthalpy of desorption. An overhead condenser feeds a reflux stream to the column, purifying the CO2-rich gas to nearly 100% CO2. The nearly pure CO2 stream exiting the stripper is compressed and transported for geological storage. Considering an inlet stream containing 3% CO (e.g., equivalent to flue gas emitted from a natural gas-fired power plant), an energy intensity of approximately 1.5 MWh per ton of CO is estimated for amine-based CO capture (heat duty for amine regeneration of 1.3 MWh per ton) and for compressing the captured CO stream from atmospheric pressure to a pipeline rating of 14 MPa (0.2 MWh per ton) (Figure 5; see solid red curve). This energy intensity decreases to 0.8 MWh per ton of CO (0.6 MWh per ton of CO for carbon capture and 0.2 MWh per ton for compression for coal-fired power plants) as the CO concentration in the inlet stream increases to approximately 12% and then remains constant. However, at inlet CO concentrations below 3% CO, the energy intensity of the amine-based process increases sharply. When the capacity of the amine in contact with air is small (approximately 0.25 moles per mole), a reboiler duty of over 5.0 MWh per ton of CO2 is required to achieve a working capacity of less than 0.05 moles per mole. This demonstrates the unique operational advantages of less energy intensive alternative mineralization processes for cases where the CO2 feed stream is significantly dilute, such as in the removal of CO2 from atmosphere or water in equilibrium with the atmosphere.

[0029] Single-Step Carbon Sequestration and Storage (sCS) 2The above considerations show that the energy consumption of mineralization-based CO2 management is primarily associated with the need to make the process alkaline. An ideal carbon sequestration process would require no consumable chemical inputs, which are costly to manufacture, transport, handle, and store. Ideally, the process could be powered using zero-carbon electrons, for example, from photovoltaic generation. Single-Step Carbon Sequestration and Storage (sCS) without Chemical Inputs 2 The process is illustrated in Figures 6 and 7. In this example, water (e.g., seawater) containing dissolved CO2, in equilibrium with the atmosphere, flows through a porous metal membrane / cathode. Application of a cathodic potential electrolyzes the water and locally generates OH at the membrane / water interface. - The concentration increases, which promotes rapid association of carbonate anions with metal cations while minimizing transport limitations and providing a substrate for heterogeneous nucleation. Specifically, flowing electrolyte through the pores of the membrane allows for the rapid association of all ionic species (OH) while providing surface sites for the nucleation and growth of metal carbonates. - , CO3 2- , and Me 2+) diffusion length scale is minimized (to the pore radius). Finite element analysis (FEA) has shown that a reasonable overpotential (≈0.5 V; see Figure 6(c)) can indeed produce highly alkaline conditions near the electroactive membrane ("electrode") surface. Indeed, in a volume of electrolyte within 200 μm of the electrode / membrane surface (e.g., significantly larger than the pore size of the electroactive membrane envisioned for such applications), highly alkaline conditions sufficient to induce carbonate precipitation are produced within 1 second of electric polarization, for the limits shown in Figure 5. For reference, the 304L stainless steel electrode is shown as a flat sheet herein, but in actual use, a coarse mesh with openings on the order of about 20 μm is assumed. This analysis confirms that the alkalinity required for carbonate precipitation is rapidly produced by applying a moderate potential. This analysis ignores electromigration and gas evolution, which cause convective mixing, but provides a lower-bound estimate of the overpotential required to induce rapid alkalinization and thus carbonate precipitation.

[0030] Electrochemical OH - A realistic energy requirement for an electromineralization process based on the production of OH can be estimated based on current state-of-the-art electrolyzers operating at 79% efficiency (e.g., 50 kWh of power to produce 1 kg of H, assuming a thermodynamic power requirement of 39.4 kWh / kg for the stoichiometric hydrogen evolution reaction). 1 kg of H produced by water electrolysis is equivalent to 1000 moles of OH, which can sequester 22 kg of CO based on stoichiometry. - ions, resulting in an energy intensity of 2.3 MWh per ton of CO2. If we take into account the calorific value of the hydrogen by-product, and assume a conversion efficiency (e.g., burning hydrogen to produce electricity) of around 60%, similar to the combustion of natural gas, the energy intensity of this process is 1.2 MWh per ton of mineralized CO2. In this analysis, 2 moles of OH - Consider the stoichiometry for mineralizing one mole of CO2 into calcium carbonate (CaCO3). Based on this, 45 kg of low-pressure H2O is needed for every ton of CO2 mineralized. 2(気体)This hydrogen is expected to have a commercial value of around $3 / kg, thereby offsetting the cost of around $135 per ton of mineralized CO2. Alternatively, if the resulting low-pressure hydrogen is converted to electricity using a hydrogen fuel cell (HFC), a conversion efficiency of around 80% could be achieved, resulting in an energy intensity of 0.84 MWh per ton of mineralized CO2. The energy intensity further drops to 1.9 MWh per ton of CO2 (without H2 capture; at $133 per ton of CO2) and 0.38 MWh per ton of CO2 (with H2 capture and 90% conversion efficiency using HFC; at $27 per ton of CO2) for an electrolyzer operating at 90% efficiency. These values ​​are based on the sCS 2 (See the yellow region in Figure 5.) In summary, this analysis demonstrates that (i) at ambient CO2 concentrations, direct electromineralization can achieve carbon removal nearly twice as efficiently as common chlor-alkali-based NaOH production and amine solvent-based processes (e.g., conservatively, >4 MWh per ton vs. <2.3 MWh per ton), and (ii) both when the energy benefits of the by-product hydrogen are considered and / or when zero-carbon energy inputs are used, this sCS 2 The approach has been shown to provide the basis for pioneering true negative emissions technology (NET).

[0031] An important advantage of mineralization using electroactive membranes to generate local alkalinity is that it enhances the precipitation kinetics due to the increase in pH, supersaturation (Ω; see Figures 4 and 6(c)), and the temperature increase (up to 60°C in solution) that occurs at the membrane surface induced by Joule heating. The electrolytic nature of the process requires a conductive (e.g., metal or composite) membrane that is mechanically and chemically stable under cathodic conditions. At such membrane surfaces, fouling is expected to occur during operation due to the formation of metal carbonates. As expected, the present sCS 2The process engineering design matches the Reynolds, Peclet, and Damkohler numbers in the electroprecipitation reactor so that the kinetics of mass transfer (of reactants) and chemical precipitation occur in correspondence with each other. As discussed herein, this is unlikely to result in substantial flux attenuation in coarse-mesh structures, but the insulating nature of mineral carbonates can actually impair current density (e.g., increasing the required overpotential) and energy efficiency. Therefore, to remove deposits, the applied potential is periodically reversed to anodically inject O and H near the membrane surface. + However, anodic conditions can lead to rapid corrosion, especially when iron-based membranes are used. Another method involves physical abrasion of deposited carbonates, similar to that used to continuously clean rotary drum filters (see, for example, Figure 6(b) and Figure 7). In these systems, the membrane surface is continuously scraped with blades that remove accumulated solids and re-expose the membrane surface. This sCS is undoubtedly 2 The concept of sCS is characterized by high energy intensity for carbon reduction. 2 This concept (a) is more efficient than most other direct air capture (DAC) approaches, (b) allows for the direct use of carbon-free electricity, for example, especially in excess cases, and (c) ensures end-to-end CO2 reduction. Furthermore, rather than requiring the construction of new chlor-alkali plants, the electrolysis reactors envisioned herein can be easily modularly integrated with existing and future desalination plants, thereby enabling CO2 removal and sequestration while producing hydrogen that can be used as drinking water and fuel. 2 An additional advantage of the process is that it produces soft water, which is an excellent feedstock for desalination plants. Currently, the energy cost of seawater desalination is about 100 times higher than that of seawater reverse osmosis (SWRO). 3 It requires 2-2.5 kWh per m of seawater, and the pretreatment step (e.g., involving substantial water softening) 3Considering that CO2 mineralization consumes 0.3-1.0 kWh per ton of water, this can be estimated at 3.5 kWh per ton of water. Combining CO2 mineralization-based pretreatment with SWRO desalination can result in energy usage that is 9% lower than the combined energy consumption of these two processes operating separately.

[0032] However, even if cation replenishment / pH adjustment is necessary, this can be easily achieved in an electrochemical system by utilizing the resulting acidity at the anode. 2 Electrolytic (re)alkalinization of reject seawater streams can be carried out by dissolving mafic and ultramafic rocks and industrial solids, including coal combustion and metal processing residues, in a weathering-enhancing form using the acidity by-product of the process. In particular, this analysis shows that aqueous forms store more CO2 per unit of alkalinity than solids. 2 moles of OH per mole of C stored as carbonate solids. - is required, whereas 1.2 moles of OH per mole of C stored as dissolved ions - As a result, only the pH is adjusted to 8-9 (e.g., 1 μM OH). - to 10 mM OH - By increasing the pH (to 100%), an additional 33 mmol of CO2 per kg of water is solubilized (Figure 3). The discharged water can therefore be engineered to have a higher pH (e.g., higher [Ca] and / or [Mg]) than the seawater from which it was extracted, further enhancing the carbon reduction benefits. Therefore, schemes for removing atmospheric CO2 need to be carefully combined with (re)alkalinization of seawater to enhance its CO2 capacity, which is driven by ocean-atmosphere equilibrium.

[0033] Disposal of Carbonate Solids: The capture of CO2 in mineral carbonates can occur rapidly, enabling stable and permanent storage while eliminating the risk of post-sequestration release. Assuming calcite stoichiometry and precipitation, removing 10 Gt of CO2 from the atmosphere (by dissolving in seawater) could produce approximately 20 Gt of solids per year. A portion of these solids could replace the global limestone market across construction materials (aggregates) and specialty uses. In the United States, 68% of crushed stone produced consists of carbonate rock, with approximately 1 Gt of production used in construction and as a feedstock for cement manufacturing. Unusable solids can be disposed of through existing solid waste management plans. In 2016, global municipal solid waste generation, as well as industrial, agricultural, and construction and demolition waste, amounted to approximately 25 Gt. In the United States, landfilling solid waste costs approximately $45 per ton, and landfilling 10 Gt of carbonate solids would require approximately 6.8 km of landfill space per year. 3 (6.8 billion m 3 ) of space. Rather than constructing a new landfill, these solids can also be stored in abandoned mines. In 2017, 53 Gt of metallic and non-metallic ores, 15 Gt of fossil fuels, and 24 Gt of biomass were extracted worldwide. However, off-site storage requires transportation of the solids, which can cost 1000 m² per km². 3 More realistically, especially when seawater is used as the alkalinity source, the sediment could be redeposited into the ocean (e.g., in the manner of brines produced in desalination; in this case, the ocean is supersaturated with respect to calcite and magnesite, allowing these solids to remain stable and non-reactive), or used for land reclamation and erosion control purposes.

[0034] Under the London Protocol, amended and implemented in 2006, ocean dumping is prohibited, with the exception of potentially permissible wastes, as outlined in the "reverse list" of Annex 1. Calcium and magnesium carbonates potentially qualify as "inert geological materials" that could be permitted for disposal in the ocean, where they can remain stable, because near-surface seawater is supersaturated with respect to both phases. If the dissolved calcium and magnesium are derived from sources other than seawater (e.g., saline groundwater), precipitated calcium and magnesium carbonates could be used to buffer the decline in ocean pH caused by either atmospheric CO2 absorption or direct CO2 injection, through the addition and dissolution of limestone. Returning to reclamation considerations, a simple model of Southern California's coastline movement suggests that for every meter of sea-level rise, coastline retreat approaches approximately 30 meters. Assuming an average shelf depth of 50 meters, the production of 20 gigawatts of solids could reverse this effect along 4,500 kilometers of coastline, roughly half the length of Florida's Gulf Coast. The creation of new land from solids derived from CO2 mineralization has the potential to not only address future CO2 emissions but also reverse one of the most significant effects of climate change. It could address the threat of land and habitat disappearance due to sea level rise while providing a CO2 storage solution that is both permanent and does not require continuous monitoring. 2 A detailed analysis of mechanisms for financially subsidizing CO2 management approaches, particularly the associated capital costs, is beyond the scope of this study. Nevertheless, the recent 45Q tax credit in the United States and California's Low Carbon Fuel Standard (LCFS) incentivize carbon reduction by implicitly pricing CO2 between $35 and $180 per ton. Such incentives provide an important, and potentially essential, pathway for enabling and empowering global CO2 reduction and mitigation.

[0035] This sCS to the CO2 problem 2The pathway differs from conventional carbon capture and geological sequestration schemes. Unlike conventional absorbent-based CO2 capture processes, where substantial energy consumption is associated with (1) demixing CO2, often at dilute concentrations (<15% by volume) from gas mixtures, and (2) the energy consumption required for CO2 desorption, the present sCS 2 The approach relies on electrolysis-enhanced carbonate mineral precipitation in a process that can operate entirely using renewable energy. However, this requires filling a significant gap in the supply of carbon-free electricity to achieve practical viability. Ultimately, this approach enhances and ensures the permanence of CO2 storage by stabilizing solid carbonates, while eliminating the need for monitoring and verification of CO2 sequestration and storage. Given that carbon storage needs to last for thousands of years, especially since NETs are deployed in the short to medium term (5-10 years), only by combining this electrolytic seawater CO2 mineralization with accelerated silicate / carbonate weathering could provide us with a viable, environmentally friendly, and potentially more acceptable approach to solving the global carbon crisis than conventional geological sequestration.

[0036] In some embodiments, the sCS 2 The approach involves the integration of an electroactive mesh composition into a "rackable and stackable" flow-through reactor (see Figure 7) for scalable CO2 reduction without the need for any stoichiometric reactants or additives, in a design specifically adapted for direct air capture (DAC). Here, water (e.g., produced water, groundwater, or seawater) containing dissolved alkali cations and dissolved CO2 (in equilibrium with air) flows through a porous conductive mesh / cathode. Application of a cathode potential electrolyzes the water at the mesh / water interface, locally generating OH. - The increased concentration of carbonate anions and metal cations (e.g., Ca) minimizes transport constraints and provides a substrate for heterogeneous nucleation. 2+ , Mg 2+) on the cathode surface (Figure 7). Two rationales underlie this hypothesis: (1) the formation of OH - The electrochemical generation of OH and the nucleation and growth (N&G) of metal carbonates are rapid reactions. Therefore, the rate of crystal growth is limited by the transport of ions to the growing nuclei. OH electrochemically generated along the porous mesh / electrode - , and simultaneously the electrolyte flowing through the pores of the mesh provides surface sites for the N&G of metal carbonates, thereby enhancing the reaction rate while dissolving all ionic species (OH - , CO3 2- , Ca 2+ , and Mg 2+ (2) Heterogeneous nucleation is favored over homogeneous nucleation due to the lower energy barrier to crystal growth (e.g., 5 kJ / mol versus 12.5 kJ / mol for CaCO3). Therefore, providing a surface (e.g., mesh / electrode) with the highest pH promotes carbonate precipitation while sequestering atmospheric CO2.

[0037] In support of this approach, experimental data and finite element analysis (FEA) have shown that highly alkaline conditions (pH > 10) readily occur in the vicinity (e.g., within 200 μm) of the electroactive mesh / cathode surface at reasonable overpotentials (≈0.5 V). Although carbonate formation on the mesh surface may limit the electron transfer reaction, this sCS 2The process can incorporate physical methods (e.g., scraping and / or washing) to remove precipitate and restore the mesh / cathode surface, similar to those used in industrial rotary drum filters. The precipitate can be collected and / or disposed of as suspended solids in a manner similar to the brine produced in desalination (Figure 7). Electrolytic (re)alkalinization of the reject seawater stream by dissolving alkaline rocks and industrial solids (coal combustion residues) can enable the absorption of even more CO2 from the atmosphere in a weathering-enhancing form. Furthermore, the electroactive mesh structures that can be developed herein feature superior performance (e.g., based on energy per unit of CO2 captured, mineralized, or rejected) compared to existing absorbents and membranes for DAC.

[0038] This approach takes advantage of the significantly higher concentrations of CO2 in water compared to air, conditioned by air-seawater equilibration. Seawater, with its current average pH of 8.1, contains 150 times more CO2 than an equivalent volume of air (Figure 3), thus significantly reducing the amount of fluid to be treated. Although the relative density ratio of seawater to air is greater than this concentration multiplication factor, pumping water is more efficient than air, and less water needs to be treated to remove the same amount of CO2. Furthermore, this sCS 2 The approach takes advantage of the favorable thermodynamics of carbonate precipitation from alkaline solutions. The thermodynamic driving force for precipitation is Ω = IAP / K at saturation. sp where IAP is the ionic activity product and K sp is the solubility product. In the case of calcite, this is the solubility product of Ca in solution at equilibrium. 2+ and CO3 2- The difference in Gibbs free energy is a function of the solution composition according to ΔG = RTlnΩ, where R is the gas constant and T is the temperature. The standard Gibbs free energy of formation ΔG f 0 CO2 (gas): -394.3 kJ / mol, CO3 2-: -527.8 kJ / mol, and CaCO3 calcite: -1129.1 kJ / mol, which indicates that carbonate precipitation ("CO2 mineralization") is thermodynamically downhill. カルサイト rises, ensuring the precipitation of calcite (and / or magnesite or other carbonates) (Figures 4 and 6). The reactions involved in carbonate precipitation in alkaline solutions are rapid. Under well-mixed conditions at 25°C and 1 atmosphere (1 bar), the equilibrium represented by Co2 (gas) ⇔ Co2 (aqueous) is t = 5.0 × 10 -11 Occurs within seconds. Co2 (aqueous solution) + H2O ⇔ H2CO3, H2CO3 ⇔ H + +HCO3 - , and HCO3 - ⇔H + +CO3 2- Aqueous species described by H2CO3, HCO3 - , and CO3 2- is 10 -2 In alkaline solutions (pH > 10), OH - HCO3 by reaction with - An alternative route to the solvation of CO2 by the formation of HCl (k=6.6×10 -4 M -1 s -1 ) is even faster than (k=8.5×10 3 M -1 s -1 The calcite precipitation rate in high salinity water (over 0.5M NaCl) is 3.2 × 10 6 Ms -1 shows the precipitation rate constant, and the yield is calculated from experimental precipitation data by R p =k(Ω-1) n (In the formula, R p is the precipitation rate, k is the rate constant, Ω is the saturation exponent, and n is the reaction order. Thus, in a well-mixed system with low mass transport resistance, CaCO3 precipitation is rate-limiting. The net reaction is 2+ +CO2+2OH - →CaCO3 + H2O and Mg 2++CO2+2OH - →MgCO3 + H2O. According to these stoichiometries, 1 mole of CO2 is converted to 1 mole of aqueous Ca 2+ or Mg 2+ and 2 moles of OH are required to produce 1 mole of CaCO3 or MgCO3. - For typical seawater, under cation-limited conditions (relevant boundary conditions), 2.86 g of CO2 are mineralized per 1000 g of treated water (Figure 4).

[0039] For clarity, we simulated the pH distribution of the scaled reactor. In this simulation, the electrode reactions are considered as follows: (1) At the anode, oxygen evolution reaction (OER): 2H2O → O2 + 4H + +4e - (2) At the cathode, (2a) oxygen reduction reaction (ORR): O2 + H2O + 4e - →4OH - , and (2b) Hydrogen Evolution Reaction (HER): 2H2O + 2e - →H2+2OH - is.

[0040] The electrochemical behavior of 304L stainless steel is shown in Figure 8(a). Dissolved oxygen in solution promotes ORR (but not HER) at negative overpotentials, with a 4 × 10 -7 A / cm 2 A diffusion-limited current of 1000 kJ / cm2 is obtained. Such a limiting current can be overcome by HER (e.g., water decomposition), which follows a Tafel relationship with the applied overpotential. ORR can generate local alkalinity at the cathode up to pH 10, while HER promotes the generation of even higher pH, albeit at higher cell potentials.

[0041] Book sCS 2The process consists of one major unit operation, as shown in Figure 9. In this unit operation, Ca- and Mg-rich water (e.g., seawater, produced water, groundwater) saturated with CO2 from air at atmospheric conditions (approximately 23°C, 1 bar total pressure, and approximately 400 ppm CO2) is introduced into the electrolytic flow reactor.

[0042] Two configurations are disclosed as non-limiting examples, using either (A) planar electrodes (FIG. 9(a)) or (b) tubular electrodes (FIG. 9(b)). In (a), a mesh cathode is placed in the center of a rectangular shell made of non-conductive material, thereby forming two chambers (FIG. 9(a)). The anode is inserted near the wall of one of the chambers. In (B), the anode and cathode are radially arranged within a non-conductive tube, similar to the configuration shown in FIG. 4 (FIG. 9(b)). Seawater (105 mg CO2 equivalent C per liter, see FIG. 3) flows through a precipitation reactor consisting of a mesh / cathode-anode system described below. Cl at the anode, produced by electrolysis of seawater, is released. 2(気体) The generation of [OH] can be suppressed by using an oxygen-selective material (e.g., MnO2) as a coating on the anode, which has an OER efficiency of 95–100%, allowing the use of a single electrolyte (seawater). Within the reactor, application of a cathodic potential results in the formation of [OH] at the cathode / water interface. - ] rises and precipitation occurs. This is shown in a simulation of the pH distribution within the pores of the electroactive mesh (Figure 10). Nearly neutral seawater enters the pores and becomes progressively more alkaline, up to pH 12 (Figure 10(a)), to an extent that depends on the current density (Figure 10(b)), and to an extent that depends on the flow rate (Figure 10(c)).

[0043] The electroactive mesh composition and flow reactor enable seawater-mediated DAC, taking advantage of the thermodynamically favorable mineralization reaction while simultaneously utilizing both the technical advantages of membrane-based water treatment systems and the substantially higher amounts of CO2 in seawater than in air at ambient conditions. 2Since this does not impair the process, and in fact fouling is a goal of the process, simple mechanical removal of solids and / or periodic polarity reversal are possible means of membrane regeneration.

[0044] Book sCS 2 The process is significantly more energy efficient than existing direct air capture (DAC) methods. First, the energy intensity of conventional carbon capture and storage (CCS) is estimated using Aspen Plus® by considering a monoethanolamine (MEA)-based process consisting of an absorber, stripper, chiller, and four-stage compressor. The energy requirements escalate sharply at inlet CO2 concentrations below 3% CO2 by volume, extrapolating to over 3 MWh / t-CO2 at 0.04%, primarily due to the increased thermal energy required for CO2 desorption from low solvent loadings. 2 The energy requirements are primarily related to the electrolysis of water. A state-of-the-art electrolyzer operating at 79% efficiency (e.g., 50 kWh of electricity to produce 1 kg of H2, assuming a thermodynamic requirement of 39.4 kWh / kg of OH) requires 1000 moles of OH. - ions, which can mineralize 22 kg of CO2 on a stoichiometric basis with an energy intensity of 2.3 MWh per ton of CO2. For an electrolyzer operating at 90% efficiency, the energy intensity drops to 1.9 MWh per ton of CO2. Thus, the expected power requirement for the process in Figure 4 (2 kg of CO2 per day) is about 0.2 kW (about 4.6 kWh per day). Energy is also required to pump the water, i.e., (i) through the mesh (for 40 μm mesh opening, ≈10 psi; 1.2 kWh per ton of CO2) and (ii) against gravity (e.g., 1 meter total dynamic head; 1.3 kWh per ton of CO2). [Table 1]

[0045] The processes disclosed in some embodiments herein are functionally similar to membrane-based DAC approaches, except that removal is based on electrically induced chemical reactions rather than size or charge exclusion. Metrics such as (1) throughput, (2) energy intensity, and (3) carbonate single-pass yield can provide relevant information similar to those obtained for conventional membrane-based processes. These data support the rapidity of the electrolytic precipitation reaction (k ≈ 3.2 × 10). 6 Ms -1 ) and therefore the yield is limited by the amount of cation present. For Ca, Mg limited reactions, 60% and 100% conversion provide the "measured" and "designed" metrics.

[0046] In some embodiments, the low-pressure hydrogen produced is converted to electricity using a hydrogen fuel cell (HFC), which can achieve conversion efficiencies on the order of 80%, resulting in a net energy intensity of 0.84 MWh per tonne of CO2 mineralized.

[0047] The feasibility of (a) electroactive mesh materials and (b) mesh-incorporated flow reactors for enabling water alkalinization and promoting ultrafast precipitation has been demonstrated in the treatment of chromium-containing water, where pH fluctuations along the mesh surface / cathode enabled rapid Cr(OH)3 deposition at the membrane / water interface (Figure 11). The meshes included (a) baseline meshes based on 316L stainless steel (SS) mesh or perforated sheets, (b) nonmetallic carbon-based meshes (carbon nanotube (CNT) / polymer / exfoliated graphite composites), and (c) SS meshes with locally sintered titanium films (Magneli phase sintered TiO7 materials). The latter two mesh compositions were selected for their high electrical conductivity and stability in seawater, especially under anodic conditions that can corrode Fe-based materials (requiring periodic mesh cleaning). The selected materials are characterized by their low cost and easy processability, which allows for the easy fabrication of many form factors, including porous structures (e.g., coarse meshes with openings in the μm-mm range). For example, porous TiO materials are easily produced by sintering and thermal reduction of TiO powders. They can also be formed by applying doctor blade treatment to deposit particles of several hundred inches in size. 2 It is also possible to rapidly fabricate carbon electrode mesh materials spanning the nanometer and nanometer ranges, and (ii) fabricate large-scale CNT-based membranes by air-brushing a percolated network of CNTs onto a porous polymer support and then cross-linking it with a polymer, e.g., polyvinyl alcohol (PVA) (see Figure 11). These composite materials are stable and conductive, with pore sizes ranging from nm to mm.

[0048] Various metal and carbon-based meshes / electrodes suitable for inducing pH fluctuations in saline can be used. In particular, stainless steel (SS) (m in the case of sintered mesh) 2These include the use of porous geometries (e.g., meshes or nonwoven mats) composed of polymers such as titanium dioxide (approximately $12 per gram, or $0.05 per gram), Magneli phase-sintered TiO materials (synthesized from TiO, approximately $0.10-$0.20 per gram), and carbon nanotube (CNT) / polymer / exfoliated graphite (eG) composites (e.g., CNTs cost approximately $3-$30 per gram, while eG synthesized from graphite costs approximately $0.10 per gram). Mesh materials (<5 cm x 5 cm) with various porosities (15-40%) and pore sizes (0.1 μm-100 μm, corresponding to a pressure drop of less than 15 psi) can be used (smaller pores allow for higher pH at lower overpotentials, but require a larger driving force to push water through). For SS, commercially available mesh materials can be used (e.g., sintered metal sheets made from 304 and 316L SS with pore sizes ranging from 37 μm (400 mesh) to 1 μm (for sintered SS plates)). To fabricate TiO7-coated mesh, purchased TiO2 powder can be placed in a gel mold, sintered under air flow at 1050 °C, and then reduced under H2 gas flow at 1050 °C, conditions that produce substoichiometric TiO7. An alternative synthesis approach is a combination of the sol-gel method and vacuum carbothermal method. Carbon-based meshes can be fabricated by spray-coating a CNT / eG suspension onto porous polytetrafluoroethylene and stainless steel supports and cross-linking using PVA. Mesh surface morphology and pore size can be observed using scanning electron microscopy (SEM); mesh roughness can be measured using atomic force microscopy (AFM). Pore size can be evaluated using SEM. The composition of the mesh can be measured using energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and quantitative X-ray diffraction using Rietveld analysis. The bulk electrochemical properties can be characterized using a four-point conductivity probe, cyclic voltammetry, electrochemical impedance spectroscopy, and electrochemical microscopy. The long-term stability of the mesh can be measured using a filtration cell with a blocked outlet at 1-200 mA / cm. 2It can be evaluated for over 168 hours of continuous operation with a pressurized feed stream (seawater) flowing through a mesh that can be used as the cathode at a current density of 1000 kJ / s. A MnO2 coated Ti rod can serve as the anode.

[0049] In situ atomic force microscopy (AFM) can be performed on various mesh materials to optimize current density and (water) flux for carbonate precipitation by seawater electrolysis. This allows the identification of the best-performing mesh composition that aligns alkalinization kinetics with thermodynamic predictions while maximizing solid precipitate formation. Electrochemical AFM equipped with a fluid cell and temperature control, a potentiostat, and a photothermal probe excitation module that enables high-speed imaging can be used for screening analyses.

[0050] The current density and topography of the carbonate overgrowth layer on the mesh surface can be monitored while applying various overpotentials (0.0 V to 2.0 V) on a 1 cm x 1 cm x ≤ 0.25 cm mesh sample mounted in a fluid cell containing simulated seawater. The fluid cell features separate liquid and gas exchange ports. The aqueous environment to which the mesh is exposed can be controlled in real time (e.g., during application of potential and data collection) by exchanging solutions or gases within the fluid cell using a programmable syringe pump. For example, dissolved Ca 2+ and Mg 2+To replenish dissolved CO2 (e.g., extracted from solution by CaCO3 precipitation), simulated seawater is exchanged through a sealed cell at a flow rate commensurate with its depletion from solution. Alternatively, air can be flowed through the cell to replenish dissolved atmospheric CO2 without replenishing cations. The kinetics of carbonate growth (e.g., rate, morphology) can be assessed by collecting time-series images over periods ranging from seconds to hours. Precipitate morphology can be tracked by measuring aspect ratio, thickness, and surface coverage, which may affect the progress of electrolytic precipitation by inducing resistive losses / Joule heating at the mesh surface. Changes in precipitate growth rate over time can also be assessed (to fix solution composition and pCO2). The solution's Ω can be estimated from modeling changes in pH at the surface and gas / liquid exchange rates. Therefore, electrolytic conditions (e.g., applied potential, flow rate, Ω) that maximize growth rate can be identified. A mesh can be selected that allows the highest yield and carbonate precipitation rate with minimal overpotential and a decrease in carbonate growth rate over time due to, for example, resistive losses. The cycling performance of a selected mesh can be tested over tens of polarity reversals while monitoring the surface topography / current density.

[0051] Definition of Terms As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to one object may encompass plural objects unless the context clearly dictates otherwise.

[0052] As used herein, the term "set" refers to a collection of one or more objects. Thus, for example, a set of objects may include a single object or multiple objects. Objects in a set may also be referred to as members of the set. Objects in a set may be the same or different. In some cases, objects in a set may share one or more common characteristics.

[0053] As used herein, the terms "connect," "connected," and "connection" refer to an operational coupling or connection. Connected items may be directly coupled to each other or indirectly coupled to each other, such as through one or more other objects.

[0054] As used herein, the terms "substantially" and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, these terms can refer not only to the exact occurrence of the event or circumstance, but also to the approximation of the occurrence of the event or circumstance. When used in conjunction with a numerical value, these terms can refer to a range of variation of ±10% or less of the numerical value, for example, ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% or less, ±0.1% or less, or ±0.05% or less.

[0055] Additionally, amounts, ratios, and other numerical values ​​may be expressed herein in a range format. It should be understood that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​expressly specified as the limits of the range, but also to include all individual numerical values ​​or subranges subsumed within that range, as if each numerical value and subrange were expressly specified. For example, a ratio in the range of about 1 to about 200 should be interpreted to include the explicitly stated limits of about 1 and about 200, but also individual ratios such as about 2, about 3, and about 4, as well as subranges such as about 10 to about 50, about 20 to about 100, etc.

[0056] Further embodiments E1. Introducing carbon dioxide into the solution; inducing precipitation of carbonate solids from said solution; Including, The method, wherein inducing precipitation of carbonate solids comprises subjecting the solution to water electrolysis.

[0057] E2. The method of E1, wherein introducing carbon dioxide into the solution is via a gas diffuser or the solution can contain carbon dioxide at a level that is in equilibrium with its environment.

[0058] E3. The method of any one of E1-2, wherein subjecting the solution to water electrolysis comprises increasing the pH of the feed solution.

[0059] E4. The method according to any one of E1 to E3, wherein subjecting the solution to water electrolysis comprises generating hydroxide ions.

[0060] E5. The method of any one of E1-4, wherein inducing precipitation of the carbonate solids comprises rotating a membrane drum in the solution while applying a suction force to draw the solution onto the surface of the membrane drum.

[0061] E6. The method according to any one of E1 to E5, wherein the solution is a brine solution.

[0062] E7. The method according to any one of E1 to E6, wherein the solution is an alkaline metal-containing solution.

[0063] E8. The method of any one of E1-7, wherein inducing precipitation of carbonate solids comprises inducing precipitation of at least one of calcium carbonate or magnesium carbonate.

[0064] E9. Introducing carbon dioxide into the solution; inducing precipitation of carbonate solids from said solution; Including, The method wherein inducing precipitation of the carbonate solids comprises rotating a membrane drum in the solution while applying a suction force to draw the solution onto the surface of the membrane drum.

[0065] E10. The method of E9, wherein introducing carbon dioxide into the solution is via a gas diffuser.

[0066] E11. The method of any one of E9-10, wherein inducing precipitation of the carbonate solids comprises subjecting the solution to water electrolysis.

[0067] E12. The method according to any one of E9 to E11, wherein the solution is a brine solution.

[0068] E13. The method according to any one of E9 to E12, wherein the solution is an alkaline metal-containing solution.

[0069] E14. The method of any one of E9-13, wherein inducing precipitation of carbonate solids includes inducing precipitation of at least one of calcium carbonate or magnesium carbonate.

[0070] While the present disclosure has been described with reference to specific embodiments thereof, those skilled in the art will recognize that various changes can be made and equivalents substituted without departing from the true spirit and scope of the present disclosure as defined by the appended claims. Moreover, many modifications may be made to adapt a particular situation, material, composition of matter, method, operation, or operations to the objective, spirit, and scope of the present disclosure. All such modifications are intended to be within the scope of the claims appended hereto. In particular, while a particular method may be described with reference to specific operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or rearranged to form equivalent methods without departing from the teachings of the present disclosure. Accordingly, unless otherwise expressly stated herein, the order and grouping of the operations described above are not intended to limit the present disclosure. The present invention provides, for example, the following items. (Item 1) 1. A method for removing carbon dioxide from a water or gas stream, comprising: contacting said gas stream containing carbon dioxide with an aqueous solution containing ions capable of forming insoluble carbonate salts, if present; contacting an aqueous solution containing carbon dioxide with an electroactive mesh that induces alkalinization of the aqueous solution, thereby precipitating carbonate solid(s) from the solution; removing said precipitated carbonate solids from said solution or from the surface of said mesh on which said carbonate solids may be deposited; The method according to the present invention. (Item 2) 2. The method of claim 1, wherein the gas flow is present. (Item 3) The method according to item 1 or 2, wherein the gas stream contains 0.04 to 100% by volume of CO2. (Item 4) 4. The method according to any one of items 1 to 3, wherein the gas fluid is atmospheric air. (Item 5) 5. The method according to any one of items 1 to 4, wherein the gas fluid is a flue gas emitted from a natural gas-fired power plant, a coal-fired power plant, an iron and steel mill, a cement plant, an ethanol plant, and a chemical manufacturing plant. (Item 6) 6. The method according to any one of items 1 to 5, wherein the aqueous solution comprises dissolved carbon dioxide in an amount in equilibrium with the gas stream. (Item 7) 7. The method according to any one of items 1 to 6, wherein the aqueous solution is in thermal equilibrium with the gas stream. (Item 8) 7. The method according to any one of items 1 to 6, wherein the aqueous solution is not in thermal equilibrium with the gas stream. (Item 9) 2. The method of claim 1, wherein the gas flow is absent. (Item 10) 10. The method according to any one of items 1 to 9, wherein the ions capable of forming an insoluble carbonate include ions comprising one or more of Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, and Al. (Item 11) 11. The method according to any one of items 1 to 10, wherein the aqueous solution has a NaCl concentration of about 1,000 ppm or more. (Item 12) 12. The method according to any one of items 1 to 11, wherein the aqueous solution has a NaCl concentration of about 30,000 ppm or more. (Item 13) 13. The method according to any one of items 1 to 12, wherein the aqueous solution comprises seawater. (Item 14) 14. The method of any one of items 1 to 13, wherein the electroactive mesh comprises a mesh cathode comprising a metal or non-metallic composition. (Item 15) Item 16. The method of any one of items 1 to 14, wherein the method utilizes an end-to-end energy intensity of about 2.5 MWh or less per ton of mineralized carbon dioxide. 16. The method according to any one of items 1 to 15, wherein the aqueous solution contains dissolved carbon dioxide in an amount that is buffered to the amount present in the atmosphere. (Item 17) 17. The method of any one of items 1 to 16, wherein the electroactive mesh enhances alkaline conditions in situ in the aqueous solution within about 2 to 20,000 μm of the electroactive mesh. (Item 18) Item 18. The method according to item 17, wherein the alkalinized state is a pH of 9 or higher. (Item 19) 19. The method according to any one of items 1 to 18, wherein the electroactive mesh comprises a metal mesh or a carbon-based mesh. (Item 20) 20. The method of claim 19, wherein the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions of these materials. (Item 21) 21. The method of any one of items 1 to 20, wherein the electroactive mesh comprises pores having diameters ranging from about 0.1 μm to about 10,000 μm. (Item 22) 22. The method of any one of items 1 to 21, wherein inducing precipitation of the carbonate solids comprises rotating a cylinder of the electroactive mesh in the solution while applying suction to draw the solution onto the outer surface of the mesh. (Item 23) 23. The method according to any one of items 1 to 22, wherein the solution is a brine solution. (Item 24) 24. The method according to any one of items 1 to 23, wherein the solution is an alkaline metal-containing solution. (Item 25) 25. The method of any one of items 1 to 24, wherein inducing precipitation of carbonate solids comprises inducing precipitation of at least one carbonate having Ca, Mg, Ba, Sr, Fe, Zn, Pb, Cd, Mn, Ni, Co, Cu, or Al. (Item 26) A flow-through electrolytic reactor comprising an entrainment device in fluid communication with a rotating cylinder comprising an electroactive mesh, and a scraping device and / or a liquid spray-based device for separating solids from a surface or solution. (Item 27) Item 27. The flow electrolysis reactor according to item 26, further comprising an aqueous solution containing carbon dioxide, Ca ions, and Mg ions. (Item 28) 18. The flow-through electrolysis reactor according to item 16 or 17, wherein the electroactive mesh is capable of inducing the removal of dissolved inorganic carbon by precipitation of carbonate solids from an aqueous solution containing carbon dioxide and ions capable of forming insoluble carbonates. (Item 29) 29. The flow electrolysis reactor according to any one of items 26 to 28, wherein the electroactive mesh comprises a metal mesh or a carbon-based mesh. (Item 30) 30. The flow-through electrolysis reactor of item 29, wherein the electroactive mesh comprises stainless steel, titanium oxide, carbon nanotubes, polymers, and / or graphite, or other hybrid compositions of these materials. (Item 31) 31. The flow electrolysis reactor according to any one of items 26 to 30, comprising a plurality of electroactive meshes. (Item 32) 32. The flow-through electrolysis reactor according to item 31, wherein the plurality of electroactive meshes are arranged in a series of parallel planar cells or parallel cylindrical cells. (Item 33) 33. The flow electrolytic reactor according to any one of items 16 to 32, in fluid communication with a desalination unit.

Claims

[Claim 1] 1. A method for removing carbon dioxide from a water or gas stream, comprising: contacting said gas stream containing carbon dioxide with an aqueous solution containing ions capable of forming insoluble carbonate salts, if present; contacting an aqueous solution containing carbon dioxide with an electroactive mesh that induces alkalinization of the aqueous solution, thereby precipitating carbonate solid(s) from the solution; removing said precipitated carbonate solids from said solution or from the surface of said mesh on which said carbonate solids may be deposited; The method according to the present invention.

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