Systems and methods for electrochemical repair of contaminants

Abstract

An electrochemical contaminant repair system includes a conditioning tank and a flow-through electrochemical reactor. The flow-through electrochemical reactor includes a housing having an internal liquid flow path. A first electrode is disposed within the internal liquid flow path. The second electrode is spaced apart from the flow-through or solid first electrode, thereby forming an electroactive gap between the flow-through or solid first electrode and the second electrode.

Description

Technical Field

[0001] The present disclosure relates to systems and methods for remediation of contaminants in liquids, and more particularly to systems and methods for electrochemical remediation of contaminants. Background Art

[0002] Water contamination and pollution problems continue to grow. Often, consumer waste is disposed of in landfills or similar collection sites. Chemicals in the waste can seep into the soil below and eventually reach and contaminate groundwater. Chemical groundwater contamination can pose significant health risks to the general public around the contamination.

[0003] While some contaminants can be broken down into benign substances in landfills through exposure to, for example, biological agents, others are not easily broken down. Some examples of such contaminants that have recently been found in large quantities in groundwater are perfluoroalkyl and polyfluoroalkyl substances, commonly referred to as "PFAS." PFAS are persistent chemicals that decay at essentially zero rate under ambient conditions and exhibit good resistance to oil, water, temperature, chemicals, and fire. PFAS can be found in a variety of consumer and industrial products, including but not limited to Ski wax, clothing, cell phones, computers, tablets, semiconductors, surgical gowns, commercial aircraft, low-emission vehicles, and firefighting foams. When products containing PFAS reach the end of their useful life, they are often discarded in landfills. Because PFAS exhibit these beneficial qualities, they also degrade very slowly, and are sometimes referred to as "forever chemicals" because these materials can take decades to degrade under environmental conditions.

[0004] While research on the effects of PFAS on humans is still ongoing, some potential health issues associated with high PFAS levels in the blood include increased cholesterol, decreased immune function, changes in liver enzymes, increased blood pressure, and an increase in some forms of cancer. PFAS can enter the bloodstream in a variety of ways, such as by ingesting contaminated water, contaminated fish, poultry or meat, contaminated soil or dust, or contaminated food packaged in or contained in packaging materials containing PFAS. Due to the potential harmful effects of PFAS, efforts are being made to reduce the amount of PFAS in drinking water. One way to reduce the amount of PFAS in drinking water is to reduce the amount of PFAS-containing materials disposed of in landfills. However, it is not feasible to completely eliminate PFAS-containing materials. However, PFAS that seep into groundwater sources can be effectively removed before or during treatment, such as by municipal water treatment plants, to make the water safer to drink.

[0005] Currently, PFAS are most often removed from water by employing adsorption and filtration methods, such as adsorption on activated carbon, adsorption on ion exchange resins, and high-pressure (reverse osmosis or nanofiltration) membranes. However, current treatment methods are expensive, impractical for large-scale treatment, may require high pressures, and may produce wastes containing very high concentrations of PFAS in waste streams. Additionally, when activated carbon or ion exchange resins can no longer remove these compounds, they must be removed and typically incinerated as hazardous waste or placed in landfills, thus continuing the cycle of disposal and leaching. Summary of the invention

[0006] According to some examples, the electrochemical contaminant remediation system includes a conditioning tank having an untreated liquid input and a conditioning agent input. The conditioning tank is configured to receive untreated liquid from the untreated liquid input and to receive the conditioning agent from the conditioning agent input or from a storage tank containing an adsorbent or ion exchange resin and to accommodate the untreated liquid and the conditioning agent. The untreated liquid and the conditioning agent are mixed and combined in the conditioning tank to produce a conditioned solution in the conditioning tank. The conditioned solution flow path connects the conditioning tank to a flow-through electrochemical reactor fluid. The conditioned solution flow path is configured to receive the conditioned solution from the conditioning tank and deliver the conditioned solution to the flow-through electrochemical reactor. The flow-through electrochemical reactor includes a housing having an internal liquid flow path, a first electrode is disposed in the internal liquid flow path, and a second electrode is spaced apart from the first electrode, thereby forming an electroactive gap between the first electrode and the second electrode. The conditioned solution passes through the electroactive gap. The untreated liquid contains contaminants, and the conditioning agent includes a material that merges with the contaminants to produce a complex, and the complex is electrostatically attracted to the surface of the first electrode.

[0007] According to other examples, a method for removing contaminants from a liquid comprises mixing a liquid including contaminants with a conditioning agent to form a conditioned solution comprising a contaminant / conditioning agent complex. The conditioned solution is delivered to a flow-through electrochemical reactor. An electric current is applied to the flow-through electrochemical reactor to produce a first charged electrode and a second charged electrode. The first charged electrode and the second charged electrode are spaced apart from each other by an electroactive gap. At least some of the contaminant / conditioning agent complexes located within the electroactive gap are electrostatically attracted to a first electrode surface. The contaminant / conditioning agent complex is electrochemically destroyed on the first electrode surface.

[0008] The foregoing examples of electrochemical contaminant remediation systems and methods for removing contaminants from liquids using flow-through electrochemical reactors may further include any one or more of the following optional features, structures, and / or forms.

[0009] In some optional forms, the untreated water may be cooled before or once entering the conditioning tank.

[0010] In other optional forms, cooling may be accomplished by a chiller or heat transfer device.

[0011] In some optional forms, the contaminant includes PFAS.

[0012] In some optional forms, the contaminant includes 1,4-dioxane.

[0013] In some optional forms, the conditioning agent includes one or more additives selected from the group consisting of a polymer, a surfactant, an adsorbent, and an ion exchange resin.

[0014] In some optional forms, the polymer comprises polydiallyldimethylammonium chloride (poly(DADMAC)) cationic polymer.

[0015] In some optional forms, the polymer comprises a quaternary amine cationic polymer.

[0016] In some optional forms, the conditioning agent is an adsorbent selected from one or more of the following groups: organic adsorbents and inorganic adsorbents, for example, one or more selected from the following group: powdered activated carbon (PAC), granular activated carbon (GAC), carbon black, silica and activated alumina.

[0017] In some optional forms, the conditioning agent is a water cooler or heat transfer device that reduces the temperature of the mixture of untreated liquid and conditioning agent.

[0018] In some optional forms, the conditioned solution is stored for a period of time in a conditioning tank before being delivered to the flow-through electrochemical reactor.

[0019] In some optional forms, the time period is from 30 seconds to 60 minutes, such as from 2 minutes to 60 minutes.

[0020] In some optional forms, a controllable valve is located between the regulating tank and the flow-through electrochemical reactor.

[0021] In some optional forms, the first electrode is an anode having a hollow cylindrical shape.

[0022] In some optional forms, the second electrode is a cathode having a hollow cylindrical shape.

[0023] In some optional forms, the wall of the second electrode has a plurality of openings.

[0024] In some optional forms, the electroactive gap is less than 5 mm.

[0025] In some optional forms, the electrochemical reactor may include a plurality of electrode pairs.

[0026] In some optional forms, the electrochemical reactor may include 1 to 10 electrode pairs.

[0027] In some optional forms, at least one of the first electrode and the second electrode is solid.

[0028] In some optional forms, at least one of the first electrode and the second electrode is porous.

[0029] In some optional forms, at least one of the first electrode and the second electrode is a cathode, the cathode comprising titanium, titanium metal or titanium oxide, and being solid or in a mesh form.

[0030] In some optional forms, the first electrode and the second electrode are arranged concentrically, the first electrode includes an anode located within the cylindrical wall of the second electrode, and the second electrode includes a cathode. In other optional forms, the first electrode and the second electrode can be reversed, wherein the second electrode including the cathode and the first electrode including the anode are arranged concentrically, and the second electrode (cathode) is located within the cylindrical wall of the first electrode (anode).

[0031] In other optional forms, the solution flow path extends at least partially longitudinally within the anode along the longitudinal axis of the anode and at least partially radially outward through the wall of the anode, substantially perpendicular to the longitudinal axis of the anode.

[0032] In other optional forms, the solution flow path extends radially through the wall of the first electrode, radially across the electroactive gap, and radially through the plurality of openings in the wall of the second electrode.

[0033] In other optional forms, the flow-through electrochemical reactor may include a power source connected to the first electrode and the second electrode.

[0034] In other optional forms, the flow-through electrochemical reactor may include an inlet cover at the first end of the housing that aligns and maintains the relative spacing between the first electrode and the second electrode.

[0035] In other optional forms, the flow-through electrochemical reactor may include an outlet guide flow cover at the second end of the housing, the outlet guide flow cover sealing the second end of the housing and receiving the outlet flow from outside the second electrode, the outlet guide flow cover also sealing one end of the first electrode.

[0036] In other optional forms, the second electrode may include: an iron-based alloy such as stainless steel; a carbonaceous material such as graphite; a dimensionally stable anode (DSA); a Magneli phase titanium oxide (general formula Ti n O 2n-1); mixed metal oxides (such as TiO2, RuO2, IrO2 and / or SnO in combination with another metal oxide, typically titanium dioxide); boron-doped diamond (BDD); or combinations thereof, such as magneli phase titanium oxide coated onto a support mesh made of stainless steel.

[0037] In other optional forms, the first electrode may include a dimensionally stable anode (DSA); a Magneli phase titanium oxide (general formula Ti n O 2n-1 ); mixed metal oxides (such as TiO2, RuO2, IrO2 and / or SnO in combination with another metal oxide, typically titanium dioxide); boron-doped diamond (BDD); or combinations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter regarded as forming the present invention, the present invention will be better understood from the following description taken in conjunction with the accompanying drawings.

[0039] Figure 1 is a schematic diagram of an electrochemical pollutant remediation system including a flow-through electrochemical reactor.

[0040] Figure 2 is a schematic diagram of an alternative embodiment of an electrochemical contaminant remediation system including a flow-through electrochemical reactor.

[0041] Figure 3 It can be used for Figure 1 or Figure 2 An exploded perspective view of one example of a flow-through electrochemical reactor of an electrochemical contaminant remediation system.

[0042] Figure 4 yes Figure 3 Side view of a flow-through electrochemical reactor.

[0043] Figure 5 yes Figure 3 Side cross-sectional view of a flow-through electrochemical reactor.

[0044] Figure 6 yes Figure 3 Close-up side cross-sectional view of the inlet cover of a flow-through electrochemical reactor.

[0045] Figure 7 yes Figure 3 Close-up side cross-sectional view of the outlet cover of a flow-through electrochemical reactor. DETAILED DESCRIPTION

[0046] The electrochemical contaminant remediation systems and methods described herein advantageously remove contaminants from water quickly and efficiently. In addition, the systems and methods described herein are particularly useful for remediating persistent contaminants that are believed to be chemically stable and effectively have a decay rate of substantially zero under ambient conditions, such as PFAS.

[0047] Although there are electrochemical remediation systems for treating PFAS and other refractory materials, they are limited by the mass transfer of pollutants to the electrode surface. Once adsorbed to and / or close to the electrode surface, these pollutants can undergo direct electron transfer reactions and then partially or completely converted into components, including but not limited to carbon dioxide, fluoride and sulfate, thereby reducing the harm to the environment and human health. However, the rate of destroying pollutants by existing systems and methods is very slow and inefficient.

[0048] The systems and methods described herein increase the mass transfer rate of contaminants near the electrode surface and / or the degree of adsorption to the electrode surface by including a modifier, which increases the efficiency of the reactor, thereby improving throughput, performance and / or reducing the electrical requirements of the electrochemical reactor, such as power and voltage.

[0049] Now turn to Figure 1 , schematically illustrates an electrochemical contaminant remediation system 1000, which includes a conditioning tank 1020. The conditioning tank 1020 has an untreated liquid input 1030 and a conditioning agent input 1034. The conditioning tank 1020 is configured to receive untreated liquid from the untreated liquid input 1030 and to receive a conditioning agent from a conditioning agent input 1034 and to contain the untreated liquid and the conditioning agent. The conditioning agent input 1034 is operably connected to a source of conditioning agent 1036. The untreated liquid and the conditioning agent are mixed and combined in the conditioning tank 1020 to produce a conditioned solution in the conditioning tank 1020. In some embodiments, the conditioning tank 1020 may include a mixing device 1022, such as a mechanical mixing device. In some embodiments, the mechanical mixing device may include a rotating paddle, a fan, or an impeller blade. In other embodiments, the mixing device 1022 may include a flow-through mixing device such as a venturi tube. In other embodiments, the mixing device 1022 may include a bubble aerator. In other embodiments, the mixing device 1022 may include a hydraulic mixing device.

[0050] As used herein, a regulator means a material or material mixture that is usually formed by charge neutralization, absorption, adsorption or a combination thereof. More specifically, in the disclosed system and method, a contaminated liquid is cleaned or purified by a regulator that forms a complex with the pollutant material in the liquid. Therefore, as used herein, a regulator is a material that is merged, compounded, adsorbed, interacted and / or combined with pollutant molecules (usually PFAS). By merging or combining with pollutant molecules, the regulator / pollutant complex obtains increased insolubility, which causes the merged regulator / pollutant part to be more easily delivered to the vicinity of the electrode surface and / or more completely adsorbed to the electrode surface. The adsorbed regulator / pollutant molecules are then degraded and destroyed by electrochemical reactions on or near the electrode surface.

[0051] In other embodiments, the conditioning agent may include heat transfer. For example, the cooling jacket 1099 may cool the conditioned liquid in the conditioning tank 1020. Although it is generally believed that heat increases chemical reactions, counterintuitively, the inventors have found that cooling the conditioned liquid enhances the destruction of contaminants (e.g., PFAS) in the flow-through electrochemical reactor 1010. In other embodiments, the untreated liquid may be cooled by a cooling device before being delivered to the mixing tank 1020. Although cooling alone may increase the destruction of contaminants, the addition of additional conditioning agents to the disclosed cooling systems and methods for remediating contaminants in liquids significantly increases the destruction of contaminants relative to cooling alone.

[0052] The conditioning agents useful in the devices and methods according to the present disclosure can be classified using one or more of four basic categories: polymers, including anionic polymers (e.g., polyanionic cellulose or polyacrylamide that also contains acrylate monomer units), nonionic polymers (e.g., polyacrylamide), cationic polymers (e.g., polyquaternium salts, also known as quaternary ammonium polymers, such as polyquaternium 6, which is also known as polydiallyldimethylammonium chloride and polyDADMAC, and polyquaternium 7, and biopolymers, such as chitosan, sulfated glycosaminoglycans, non-sulfated glycosaminoglycans, hyaluronic acid chondroitin sulfate, glucose sulfate, dextran sulfate, keratan sulfate, heparin, cyclodextrin, heparin sulfate or a combination thereof, especially a cationic biopolymer such as chitosan); a surfactant, including a cationic surfactant (e.g., a quaternary ammonium surfactant such as cetrimonium bromide); a high surface area material (e.g., a carbonaceous material such as carbon black or activated carbon, especially powdered activated carbon (PAC), granular activated carbon (GAC) and / or carbon black, and an inorganic adsorbent such as silica or activated alumina); and an ion exchange resin. PFAS (and other contaminants) can be removed from a liquid such as water by mixing a liquid including a contaminant (e.g., PFAS) with a conditioning agent in a conditioning tank to form a conditioned solution containing a contaminant / conditioning agent complex. More specifically, a conditioning agent, such as a cationic polymer, an anionic polymer, a cationic surfactant, a high surface area adsorbent or an ion exchange resin, such as polyDADMAC, cetrimonium bromide, PAC and / or carbon black, is mixed with water containing a contaminant, such as PFAS contaminated water. The regulator is combined, compounded, adsorbed, interacted and / or combined with the PFAS molecules (or other chemically stable, relatively soluble chemical pollutants) in the regulating tank to form a pollutant / regulator complex, which is electrostatically attracted and theoretically more easily adsorbed and / or transported, so that the complex is close to the electrode surface of the electrochemical reactor, thereby promoting electron transfer / transfer from the pollutant to the pollutant and its electrochemical degradation / destruction. Since electrostatic attraction is useful for forming a complex, the positively charged part has been shown to have a significant effect on the generally negatively charged PFAS species. It is believed that the negatively charged part will have similar effects in forming a complex with the positively charged PFAS species.

[0053] Regulated fluid flow path 1040 connects regulating tank 1020 to flow-through electrochemical reactor 1010 fluid. In some embodiments, regulated fluid flow path 1040 may include a pipe or conduit. In other embodiments, regulated fluid flow path 1040 may include an open channel. Optional control valve 1024 can control the flow of regulated liquid through regulated fluid flow path 1040. Control valve 1024 can be connected to a controller such as processor 1026, which sends a control signal to control valve 1024 based on time measurement, user command and / or input from sensor 1028 in regulating tank 1020 and / or from sensor 1029 in flow-through electrochemical reactor 1010 or sensor (not shown) downstream of flow-through electrochemical reactor 1010. Sensors 1028, 1029 can be wirelessly connected to processor 1026, or the connection can be wired (not shown). When the control signal is based on a time period, the time period is sufficient to ensure sufficient mixing of the regulator and the untreated liquid. Generally, any time period greater than one minute may be useful, but in practice, mixing for long time periods may be cost prohibitive. In some embodiments, the time period may be from 30 seconds to 60 minutes, such as from 2 minutes to 20 minutes, depending on the size of the conditioning tank 2020, the amount of conditioning agent mixed with the untreated liquid, and the reaction rate between the conditioning agent and the contaminant.

[0054] The regulated fluid flow path 1040 is configured to receive the regulated solution from the regulation tank 1020 and deliver the regulated solution to the flow-through electrochemical reactor 1010. The flow-through electrochemical reactor 1010 includes a housing 1012 having an internal liquid flow path 1014, a first electrode 1016 disposed within the solution flow path 1014, and a second electrode 1018 spaced apart from the first electrode 1016, thereby forming an electroactive gap 1019 between the first electrode 1016 and the second electrode 1018. Figure 1 The embodiment of the present invention shows a single electrode pair (first electrode 1016 and second electrode 1018), but other embodiments may include more than one electrode pair in the flow-through electrochemical reactor 1010. For example, each flow-through electrochemical reactor 1010 may include 2, 3, 4, 5, 6, 7, 8, 9 or 10 or more electrode pairs in a single reactor housing 1012. Increasing the number of electrode pairs in the flow-through electrochemical reactor 1010 is a way to increase the throughput of the system. In the embodiment shown, the first electrode 1016 and the second electrode 1018 include flat plates separated by an electroactive gap 1019. In other embodiments described below, the first electrode 1016 and the second electrode 1018 may include hollow concentric oriented cylinders. The conditioned solution passes through the electroactive gap 1019.

[0055] The untreated liquid contains contaminants, and the modulator combines, complexes, adsorbs, interacts and / or binds with the contaminants to produce a modulator / contaminant complex, and the modulator / contaminant complex is advantageously electrostatically attracted to the surface of the first electrode 1016. In theory, this strategy is particularly advantageous for contaminants like PFAS, which have considerable solubility in most solvents / solutions and therefore cannot be adsorbed and / or transported near the electrode surface in the considerable amounts required to achieve effective treatment.

[0056] Now turn to Figure 2 , schematically shows another embodiment of an electrochemical pollutant remediation system 2000, wherein the electrochemical pollutant remediation system includes a regulating tank 2020. Figure 1 Any features described in the embodiments may be included in Figure 2 For example, the sensors 1028, 1029 described above may be incorporated into Figure 2 but for the sake of brevity, not shown or discussed.

[0057] The conditioning tank 2020 has an untreated liquid input 2030 and a conditioning agent input 2034. The conditioning tank 2020 is configured to receive untreated liquid from the untreated liquid input 2030 and a conditioning agent from the conditioning agent input 2034 and contain the untreated liquid and the conditioning agent. The conditioning agent input 2034 is operably connected to a source of conditioning agent 2036. The untreated liquid and conditioning agent are mixed and combined in the conditioning tank 2020 to produce a conditioned solution in the conditioning tank 2020. In some embodiments, the conditioning tank 2020 may include a mixing device ( Figure 2 In some embodiments, the mechanical mixing device may include rotating paddles, fans, or impeller blades. In other embodiments, the mixing device may include a flow-through mixing device such as a venturi or static mixer. In other embodiments, the mixing device may include a bubble aerator. In other embodiments, the mixing device may include a hydraulic mixing device or may rely on turbulence of a pump or other delivery device.

[0058] The regulated fluid path 2040 fluidically connects the regulating tank 2020 to the plurality of flow-through electrochemical reactors 2010a, 2010b, 2010c. Figure 2In the embodiment of the present invention, the flow-through electrochemical reactors 2010a, 2010b, 2010c are connected in parallel with the liquid flow path 2040. Increasing the number of flow-through electrochemical reactors 2010a, 2010b, 2010c is another way to increase the throughput of the system. More or fewer flow-through electrochemical reactors 2010a, 2010b, 2010c can be used in any embodiment. For example, 2, 4, 5, 6 or more flow-through electrochemical reactors can be used in the system. In addition, some or all of the flow-through electrochemical reactors can be connected in series. In other embodiments, some flow-through electrochemical reactors can be connected in series, while other flow-through electrochemical reactors can be connected in parallel. In some embodiments, two or more flow-through electrochemical reactors in the flow-through electrochemical reactor can be further enclosed in an optional external housing 2050, thereby potentially eliminating the need for a separate regulated fluid path 1040, 2040 for each electrochemical reactor 2010a, 2010b, 2010c. Still further, in other embodiments, one or more of the reactor housings 2012 of the electrochemical reactors 2010a, 2010b, 2010c may contain a plurality of electrode pairs.

[0059] The conditioned fluid flow path 2040 is configured to receive the conditioned solution from the conditioning tank 2020 and deliver the conditioned solution to the flow-through electrochemical reactors 2010a, 2010b, 2010c. Figure 1 Similar to the embodiments, at least one of the flow-through electrochemical reactors 2010a, 2010b, 2010c includes a shell 2012 having an internal liquid flow path 2014, a first electrode 2016 disposed in the internal liquid flow path 2014, and a second electrode 2018 spaced apart from the first electrode 2016, thereby forming an electroactive gap 2019 between the first electrode 2016 and the second electrode 2018.

[0060] The conditioned solution passes through the electroactive gap 2019. The conditioned solution contains the contaminant and the conditioning agent, which includes a material that combines, complexes, adsorbs, interacts and / or binds with the contaminant to produce a conditioning agent / contaminant complex, and the conditioning agent / contaminant complex is electrostatically attracted to the surface of the first electrode 2016.

[0061] Now turn to Figure 3-7 , showing that it can be used in the above Figure 1 and 2An embodiment of a flow-through electrochemical reactor 10 in an electrochemical remediation system described in the disclosure. The flow-through electrochemical reactor 10 includes a housing 12 having an internal liquid flow path 14. A flow-through or solid first electrode, such as an anode 16, is disposed within the internal liquid flow path 14. In the illustrated embodiment, the anode 16 is annular in shape, in some cases a hollow cylinder, and includes a porous material. Advantageously, the flow-through electrochemical reactor described herein has no moving parts and therefore has a long service life while being relatively inexpensive and easy to manufacture. In addition, the flow-through electrochemical reactor described herein surprisingly and unexpectedly can more effectively treat contaminants present in the water / solution being treated, with significantly reduced clogging and short circuiting compared to previous electrochemical reactor devices.

[0062] A second electrode, such as cathode 18, is spaced apart from anode 16, thereby forming an electrically active gap 20 between anode 16 and cathode 18. In other embodiments, the concentric arrangement of anode 16 and cathode 18 may be reversed.

[0063] Figure 3-7 The anode 16 and cathode 18 in the illustrated flow-through electrochemical reactor both have a hollow cylindrical shape. In other embodiments, the anode 16 and cathode 18 may have other shapes, such as a flat plate or a partial cylinder. Figure 3 In the embodiment of FIG. 8 , the anode 16 and the cathode 18 are arranged concentrically, and the anode 16 is located within the cylindrical wall 22 of the cathode 18 . Figure 3-7 The arrangement shown in can be used as an oxidation reactor, which is particularly advantageous for destroying PFAS. In other embodiments, for example, when used as a reduction reactor (so that the electron transfer reaction occurs at the cathode rather than the anode, that is, the cathode is the working electrode), the anode 16 and the cathode 18 can be reversed (such as by reversing the electrical connection, thereby reversing the polarity of the applied current) so that the cathode 18 can be located within the cylindrical wall of the anode 16. In any case, the anode 16 and the cathode 18 can share a common longitudinal axis x. In an oxidation electrochemical reactor configuration using a porous anode, the interior 24 of the porous anode 16 forms an initial flow path for the treated solution entering the housing 12 through the inlet 26. When the conditioned solution fills the interior 24, the conditioned solution flows longitudinally parallel to the longitudinal axis x and eventually reaches the bottom of the interior 24, where the conditioned solution is blocked by the plug 27. Once blocked, pressure builds up in the interior 24, which forces the conditioned solution to flow radially outward perpendicular to the longitudinal axis x through the wall of the anode 16.

[0064] The conditioned solution may pass through the walls of the anode 16 through porous openings in the anode, through perforations in the anode 16, or around the anode. Regardless, once the conditioned solution flows through and / or around the walls of the anode 16, the conditioned solution enters the electroactive gap 20. While in the electroactive gap 20, chemical reactions occur in the conditioned solution, which are driven by the flow of electrons provided by the charged anode and cathode. The conditioned solution continues to flow radially outward through the cathode wall 22, for example, through a plurality of openings 28 in the cathode wall 22. Once through the cathode wall 22, the conditioned solution flows to the outlet 30 in the annular space formed between the cathode 18 and the housing 12.

[0065] In alternative embodiments, one or both of the anode 16 and cathode 18 may include a solid cylindrical wall. In such embodiments, the internal liquid flow path may enter the hollow interior of the anode 16, flow downward until the plug 27 is contracted, then around the bottom end of the anode 16, through the gap between the bottom of the anode 16 wall and the plug 27, then upward through the electroactive gap 20 until contacting the inlet cap 36 and through the gap between the inlet cap 36 and the top end of the cathode 18, then down to the outlet on the outside of the cathode 18. In other alternative embodiments, the anode 16 or cathode 18 may include a solid cylindrical wall, and the flow path may flow on the outer surface of the solid cylindrical wall and through the electroactive gap 20.

[0066] A power source 34 is connected to the anode 16 and cathode 18 via electrical connections 32. Typically, the power source will be a DC power source. However, if the AC power source is converted to DC in a transformer / rectifier, an AC power source may be used instead. The power source 34 charges the anode 16 and cathode 18 and the conditioned solution fills the electroactive gap 20, and electrons flow between the anode 16 and cathode 18 and drive certain desired chemical reactions, oxidizing or reducing the formed complex, which is particularly beneficial for degrading complexes including chemically stable and relatively soluble pollutants (such as PFAS).

[0067] An inlet cap 36 is disposed at a first end 38 of the housing 12, which maintains proper spacing and orientation of the anode 16 relative to the cathode 18. An outlet guide flow cap 40 is disposed at a second end 42 of the housing 12. The outlet guide flow cap 40 seals the second end 42 of the housing 12 and receives the outlet flow from the exterior of the cathode 18. The outlet guide flow cap 40 also seals one end of the interior 24 of the anode 24 with the plug 27.

[0068] Disposed at the first end 38 of the housing 12 is an adapter base inlet 44 that provides plumbing and electrical connections while maintaining a pressure seal.

[0069] In some embodiments, cathode 18 may include stainless steel, graphite or other carbonaceous materials, dimensionally stable anode (DSA), Magneli phase titanium oxide (general formula Ti n O 2n-1 , such as Ti4O7), mixed metal oxides (such as RuO2 (ruthenium oxide), IrO2 (iridium oxide), SnO (tin oxide) and / or PtO2 (platinum oxide) in combination with another metal oxide, usually titanium dioxide) or boron-doped diamond (BDD) or a combination thereof. As used herein, the term "magneli phase titanium oxide" refers to a titanium oxide having the general formula Ti n O 2n-1 Titanium oxide, such as Ti4O7, Ti5O9, Ti6O 11 or a mixture thereof. In one embodiment, the Magneli phase titanium oxide may be Ti4O7. In other embodiments, the Magneli phase titanium oxide may be a mixture of Magneli phase titanium oxides.

[0070] In some embodiments, the anode 16 may include one of the following: a dimensionally stable anode (DSA), a Magneli phase titanium oxide (general formula Ti n O 2n-1 , such as Ti4O7), mixed metal oxides (such as RuO2 (ruthenium oxide), IrO2 (iridium oxide), SnO (tin oxide) and / or PtO2 (platinum oxide) in combination with another metal oxide, usually titanium dioxide), boron-doped diamond (BDD), others or combinations thereof.

[0071] The anode 16 and / or the cathode 18 may further include a catalytic coating. The thickness of the catalytic coating may be 1 μm to 30 μm, preferably 5 μm to 20 μm and more preferably 10 μm to 20 μm. The catalytic coating may include one or more metals selected from the following group: ruthenium (Ru), rhodium (Rh), palladium (Pd), iridium (Ir), platinum (Pt) and tantalum (Ta). For example, the catalytic combination may include a combination of Ru and Ta, a combination of Rh and Ta, a combination of Pd and Ta, a combination of Ir and Ta, a combination of Pt and Ta, a combination of Ru and Ir, a combination of Rh and Ir, a combination of Pd and Ir, or a combination of Pt and Ir.

[0072] Once a suitable flow-through reactor is constructed and arranged, power is applied to the cathode and anode, and the conditioned solution is passed through the electrodes, thereby electrochemically purifying it. The purified solution is then removed from the reactor. The applied power may be reversed periodically to prevent electrode passivation and remove fouling. In this embodiment, the cathode may comprise Magneli phase titanium oxide (general formula Ti n O 2n-1) or other electrode materials. The reactor may be periodically backwashed or treated with an acid or antiscalant to remove accumulated solids that may accumulate on the electrodes.

[0073] In the illustrated embodiment, during use, power is applied to the cathode and anode, and the treated solution is transferred to the inlet cap end of the reactor and into a tubular path located vertically in the center of the reactor. The electrochemically treated solution is discharged from the outlet of the tube. Typically, the orientation of the reactor is positioned (and thus relative to the Figure 3-5 The depicted diagram is rotated 180 degrees) so that the inlet is arranged at the bottom and the outlet is arranged at the top. In such an arrangement, the electrochemically treated solution flows from the bottom to the top. In other embodiments, as discussed above, the anode and cathode can be reversed.

[0074] According to any embodiment, the flow reactor may further optionally include an oxidation-reduction potential sensor, a pH sensor, a chlorine sensor, a conductivity sensor, a flow rate sensor, a pressure sensor, a temperature sensor, one or more pollutant sensors (such as ammonia, TOC, UV-Vis, etc.) or a combination thereof.

[0075] As described above, one contaminant that may be advantageously mitigated, removed, and / or destroyed using the electrochemical contaminant remediation systems and flow-through electrochemical reactors described above is PFAS.

[0076] As previously described, the regulator is combined or combined with the PFAS molecules (or other chemically stable, relatively soluble chemical pollutants) in the regulating tank to form a pollutant / regulator complex. The regulated solution is delivered to the flow-through electrochemical reactor through the regulated solution flow path. An electric current is applied to the flow-through electrochemical reactor to produce a first charged electrode and a second charged electrode. The first charged electrode and the second charged electrode are separated from each other by an electroactive gap. At least some of the pollutant / regulator complexes in the combined pollutant / regulator complex located in the electroactive gap are electrostatically attracted to the first electrode surface. Relative to individual PFAS (or other chemically stable, relatively soluble chemical pollutants) molecules, the pollutant / regulator complex increases the electrostatic attraction / adsorption of the electrode surface in the flow-through electrochemical reactor. In other words, the regulator enhances the transport of the pollutant / regulator complex to the electrode surface. At least some of the combined pollutant / regulator complexes are adsorbed and / or electrostatically attracted so that they are close to the first electrode surface. Typically, the combined pollutant / regulator molecules are electrochemically destroyed on and / or near the first electrode surface by direct transfer of electrons from the pollutant to the anode.

[0077] The conditioned solution can be stored in the conditioning tank for a period of time before being delivered to the flow-through electrochemical reactor to ensure adequate mixing and formation of the pollutant / conditioner complex. In some embodiments, the adequate period of time is 30 seconds to 60 minutes, such as 2 minutes to 20 minutes.

[0078] The electrochemical contaminant remediation systems and flow-through electrochemical reactors described herein are advantageously used for water treatment, including but not limited to the removal of contaminants such as PFAS from industrial waste streams and municipal treatment plants used to produce drinking water. The flow-through electrochemical reactors described herein are durable and scalable to meet relatively small personal or household needs as well as relatively large consumer, commercial, municipal or industrial needs.

[0079] As used herein, a flow-through electrochemical reactor refers to a reactor having a solution flow path therethrough. The basic structural elements of a flow-through reactor include a housing having an inlet, an outlet, an anode, and a cathode, as described and shown, for example, in U.S. Patent Publication No. 2019 / 0284066, which is hereby incorporated by reference in its entirety.

[0080] As used herein, "about," "approximately," or "substantially" is inclusive of the stated value and means within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art, taking into account problematic measurements and errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system). For example, "about," "approximately," or "substantially" can mean within one standard deviation, or within ±10%, 5%, 3%, or 1% of the stated value.

[0081] As used herein, "carbonaceous" means a material that includes carbon. As used herein, to be considered "carbonaceous," a material should contain carbon atoms in an oxidation state other than +4 (such that the carbon atoms can be oxidized). For example, carbonaceous materials include, but are not limited to, graphite, graphene, fullerenes, conductive plastics, and diamond.

[0082] As used herein, "flow-through" anode or cathode refers to an anode or cathode electrode through which a liquid can flow. Some non-limiting examples of flow-through electrodes include anodes or cathodes having internal straight-through paths and / or including perforations, pores or holes through which a liquid can flow. For example, holes can be made in electrodes by punching. In one example, a solid but hollow cylindrical electrode can have an internal straight-through path, wherein liquid can flow axially along the length of the hollow cylindrical electrode. Other non-limiting examples include anodes having a material wall including a porous material, for example, hollow cylindrical anodes or cathodes having a material wall including a porous material, and liquid can flow axially along the length of the anode or cathode and flow through the cylindrical anode or cathode wall laterally through the material wall. Porous electrodes, such as porous Magneli phases, such as Ti4O7 anodes, are generally preferred because they provide high surface areas and increase contact with water / solution (usually water) to be electrochemically treated. Solid plate-type anodes (not hollow and without internal flow-through paths) can also be used. Therefore, both anodes and cathodes can be flow-through or solid.

[0083] In order for any electrochemical process to proceed, there must be two (or more) electrodes acting as anode and cathode. As used herein, "electroactive gap" means the gap or space between electrodes acting as anode and cathode. In the disclosed flow-through electrochemical reactor, the electroactive gap is contained in a flow path through which a solution (usually an aqueous phase to be treated) can flow when the electrodes of the electrochemical reactor are energized and electrons can be transferred. The current may cause various chemical reactions to occur within the electroactive gap, degrading and / or inactivating contaminants in the treated water / solution, thereby purifying water and converting non-potable water into potable water and / or remediating and thereby releasing wastewater streams into the environment.

[0084] As used herein, a "dimensionally stable anode" refers to an anode that exhibits relatively high electrical conductivity and corrosion resistance. Typically, the dimensionally stable anode is made of one or more metal oxides, such as RuO2 (ruthenium oxide), IrO2 (iridium oxide), SnO (tin oxide) or PtO2 (platinum oxide).

[0085] "Mixed metal oxide electrodes" (which can be used as anodes or cathodes) are made by coating a substrate (such as a titanium plate or expanded mesh) with a metal oxide. One metal oxide is typically RuO2 (ruthenium oxide), IrO2 (iridium oxide), SnO (tin oxide), or PtO2 (platinum oxide), or a combination thereof, which conducts electricity and catalyzes the desired reaction, such as in situ generation of chlorine gas. The other metal oxide is typically titanium dioxide, which does not conduct electricity or catalyze significantly, but prevents internal corrosion.

[0086] The following examples are provided to illustrate the systems and methods disclosed herein for remediating contaminants in liquids.

[0087] Example 1

[0088] To test the effect of cationic polymers on the electrochemical remediation of PFAS, two different polymers were evaluated. The first (C-591) was poly(diallyldimethyl)ammonium chloride (poly(DADMAC)), while the second, C-577, was another polyquaternary amine.

[0089] The tests were conducted using leachate collected from a centralized water treatment facility that treats several different leachates. Due to the high organic content in the water, rather than using raw leachate for testing, leachate was collected after coagulation and clarification with ferric chloride and lime.

[0090] For evaluation, the polymer was added to 3 gallons of leachate and then mixed for 15 minutes. Figure 3-7 As shown, water was introduced into the reactor using a porous titanium oxide (Ti4O7) anode and a titanium metal mesh cathode and recirculated for 6 hours at greater than 3 V. Water samples were collected at 2, 4 and 6 hours and sent for PFAS analysis according to EPA Method 1633. Two tests were performed with the addition of polymer, and a control test was also performed without the addition of polymer.

[0091] Once the results are obtained, determine the first order kinetic decay rate for PFAS reduction. First Order Kinetic Decay (Minutes) -1 ) constants are shown below.

[0092] Untreated C-591 C-577 Total PFAS 1.0E-03 2.0E-03 3.0E-03

[0093] These results demonstrate that by adding a conditioning agent, and in particular a cationic polymer, to an untreated liquid, mixing the conditioning agent and contaminants, in particular PFAS, in the liquid advantageously and significantly provides approximately 300% destruction of PFAS relative to electrochemical treatment alone (under the same operating conditions).

[0094] Unless expressly excluded or otherwise limited, each document cited herein, including any cross-referenced or related patents or applications and any patent application or patent to which this application claims priority or benefit, is hereby incorporated by reference in its entirety. The citation of any document does not admit that it is prior art to any invention disclosed or claimed herein, or that it teaches, indicates or discloses any such invention alone or in combination with any one or more other reference documents. In addition, in the event that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this document shall prevail.

[0095] Although specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, it is intended that all such changes and modifications within the scope of the present invention be covered in the appended claims.

Claims

1. An electrochemical pollutant remediation system, comprising: a conditioning tank comprising an untreated liquid input and a conditioning agent input, the conditioning tank being configured to receive untreated liquid from the untreated liquid input and conditioning agent from the conditioning agent input such that the untreated liquid and conditioning agent mix and combine in the conditioning tank to produce a conditioned solution in the conditioning tank; a regulated fluid flow path fluidly connecting the regulating tank with a first flow-through electrochemical reactor, the regulated fluid flow path being configured to receive the regulated solution from the regulating tank and deliver the regulated solution to the flow-through electrochemical reactor, the first flow-through electrochemical reactor comprising: a housing containing an internal liquid flow path; a first electrode disposed within the internal liquid flow path; a second electrode spaced apart from the first electrode so as to form an electroactive gap between the first electrode and the second electrode, the conditioned solution passing through the electroactive gap, and wherein the untreated liquid comprises a contaminant, and the conditioning agent comprises a material that combines with the contaminant to produce a contaminant / conditioning agent complex, and the contaminant / conditioning agent complex is electrostatically attracted to the surface of the first electrode.

2. The electrochemical pollutant remediation system of claim 1, wherein the pollutants include refractory organic materials, such as PFAS.

3. The electrochemical contaminant remediation system according to any one of claims 1 and 2, wherein the conditioning agent comprises one or more additives selected from the group consisting of a polymer, a surfactant, an adsorbent, and an ion exchange resin.

4. The electrochemical contaminant remediation system of claim 3, wherein the conditioning agent comprises a cationic polymer.

5. The electrochemical contaminant remediation system of claim 3, wherein the conditioning agent comprises one or more adsorbents selected from the group consisting of powdered activated carbon (PAC), granular activated carbon (GAC), carbon black, silica, and activated alumina.

6. The electrochemical contaminant remediation system of any one of claims 1 and 2, wherein the conditioning agent comprises an anion exchange resin. 7 . The electrochemical pollutant remediation system according to claim 1 , further comprising a controllable valve, wherein the controllable valve is located between the regulating tank and the flow-through electrochemical reactor.

8. The electrochemical contaminant remediation system of claim 1, wherein the first electrode is an anode having a hollow cylindrical shape.

9. The electrochemical contaminant remediation system of claim 1, wherein the second electrode is a cathode having a hollow cylindrical shape.

10. The electrochemical contaminant remediation system of claim 1, wherein a wall of the second electrode has a plurality of openings.

11. The electrochemical contaminant remediation system of claim 1, further comprising a mixing device located in the adjustment tank.

12. The electrochemical contaminant remediation system of claim 1, further comprising a second flow-through electrochemical reactor connected to the internal liquid flow path.

13. The electrochemical contaminant remediation system of claim 12, wherein the first flow-through electrochemical reactor and the second flow-through electrochemical reactor are connected in series.

14. The electrochemical contaminant remediation system of claim 12, wherein the first flow-through electrochemical reactor and the second flow-through electrochemical reactor are connected in parallel.

15. A method for removing contaminants from a liquid, the method comprising: mixing a liquid including a contaminant with a conditioning agent to form a conditioned solution including a combined contaminant / conditioning agent complex; delivering the conditioned solution to a flow-through electrochemical reactor; applying an electric current to the flow-through electrochemical reactor to produce a first charged electrode and a second charged electrode, the first charged electrode and the second charged electrode being separated from each other by an electroactive gap; electrostatically attracting at least some of the combined contaminant / modulating agent complexes within the electroactive gap to a first electrode surface; and The combined contaminant / modulator molecules on or near the surface of the first electrode are electrochemically destroyed.

16. The method of claim 15, wherein the contaminant comprises PFAS.

17. The method of claim 15, wherein the conditioning agent comprises one or more additives selected from the group consisting of a polymer, a surfactant, an adsorbent, and an ion exchange resin.

18. The method of claim 15, wherein the conditioning agent comprises a cationic polymer.

19. The method of claim 15, wherein the conditioning agent comprises one or more adsorbents selected from the group consisting of powdered activated carbon (PAC), granular activated carbon (GAC), carbon black, silica, and activated alumina.

20. The method of claim 15, wherein the conditioning agent comprises an anion exchange resin.

21. The method of claim 15, wherein the liquid including contaminants and the conditioning agent are mixed in a conditioning tank prior to delivering the conditioned solution to the flow-through electrochemical reactor.

22. A method according to claim 21, wherein mixing is performed for a period of time from 30 seconds to 60 minutes, such as from 2 minutes to 20 minutes.

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