Systems and methods for electrochemical purification of contaminants - Patents.com

Abstract

The electrochemical contaminant remediation system includes an equalization 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. A second electrode is spaced apart from the flow-through or solid first electrode, thereby creating 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 purifying contaminants in liquids, and more particularly, to systems and methods for electrochemical purification of contaminants. [Background technology]

[0002] Water pollution and contamination is a growing problem. Often, consumer waste is disposed of in landfills or similar dumping sites. Chemicals from the waste can leach into the underlying soil and eventually reach and contaminate groundwater. Chemical groundwater contamination can pose significant health risks to the general population in the vicinity of the contamination.

[0003] Some pollutants can be broken down into benign substances in landfills, for example by exposure to biological agents, while others do not degrade as easily. Some examples of such pollutants that have been found in large quantities in groundwater in recent years include perfluoroalkyl and polyfluoroalkyl substances, commonly referred to as "PFAS". PFAS are durable chemicals with essentially zero decay rates under ambient conditions and exhibit good oil, water, heat, chemical, and fire resistance. PFAS are found in a variety of consumer and industrial products, including but not limited to Teflon, Scotchgard, ski wax, clothing, cell phones, computers, tablets, semiconductors, surgical gowns, commercial aircraft, low-emission vehicles, and firefighting foam. Products containing PFAS are often disposed of in landfills when they reach the end of their useful life. Because PFAS exhibit the above advantageous qualities, they also degrade very slowly, sometimes referred to as "forever chemicals" because it can take decades for these materials to break down under ambient conditions.

[0004] Although research into the effects of PFAS in humans is still ongoing, potential health problems correlated with high PFAS levels in the blood include increased cholesterol, decreased immune function, changes in liver enzymes, elevated blood pressure, and increased incidence of some forms of cancer. PFAS can enter the bloodstream in several ways, for example, by ingesting contaminated water, contaminated fish, poultry, or meat, contaminated soil or dust, or contaminated foods that are packaged or contained in packaging materials that contain PFAS. Due to the potentially harmful effects of PFAS, efforts are underway to mitigate the amount of PFAS in drinking water. One way to mitigate the amount of PFAS in drinking water is to reduce the amount of PFAS-containing materials that are disposed of in landfills. However, complete elimination of PFAS-containing materials is not feasible. However, PFAS that leach into groundwater supplies can be effectively removed before or during treatment, for example, by municipal water treatment plants, making the water safer for consumption.

[0005] Currently, PFAS are most often removed from water by applying adsorption and filtration methods such as activated carbon adsorption, ion exchange resin adsorption, and high pressure (reverse osmosis or nanofiltration) membranes. However, current treatment methods are expensive, impractical for large-scale treatment, may require high pressure, and can generate waste that contains very high concentrations of PFAS in the waste stream. In addition, when activated carbon or ion exchange resins can no longer remove these compounds, they must be removed, often incinerated as hazardous waste or placed in landfills, thereby continuing the cycle of disposal and leaching. Summary of the Invention

[0006] According to some examples, an electrochemical contaminant remediation system includes an equalization tank having an untreated liquid input and a conditioner input. The equalization tank is configured to receive and contain untreated liquid from the untreated liquid input and a conditioner from the conditioner input or from a holding tank containing an adsorbent or ion exchange resin. The untreated liquid and the conditioner are mixed and combined in the equalization tank to produce a conditioned solution in the equalization tank. A conditioned solution flow path fluidly connects the equalization tank to a flow-through electrochemical reactor. The conditioned solution flow path is configured to receive the conditioned solution from the equalization 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 disposed in the internal liquid flow path, and a second electrode spaced apart from the first electrode to create an electroactive gap between the first electrode and the second electrode. The conditioned solution passes through the electroactive gap. The untreated liquid includes a contaminant, and the conditioner includes a material that combines with the contaminant to form a complex, and the complex is electrostatically attracted to a surface of the first electrode.

[0007] According to another example, a method of removing contaminants from a liquid includes mixing the liquid containing the contaminants with a modifier to create a conditioned solution containing contaminant / modifier complexes. The conditioned solution is delivered to a flow-through electrochemical reactor. A current is applied to the flow-through electrochemical reactor to generate a first charged electrode and a second charged electrode. The first charged electrode and the second charged electrode are spaced apart from one another by an electroactive gap. At least some of the contaminant / modifier complexes located within the electroactive gap are electrostatically attracted to a first electrode surface. The contaminant / modifier complexes are electrochemically disrupted on the first electrode surface.

[0008] The above-described examples of electrochemical contaminant remediation systems and methods for removing contaminants from a liquid using a flow-through electrochemical reactor may further include any one or more of the following optional features, structures, and / or configurations.

[0009] In some options, the untreated water may be cooled before entering the equalization tank or after entering the equalization tank.

[0010] In another option, cooling may be achieved by a chiller or heat transfer device.

[0011] In some optional embodiments, the contaminant comprises a PFAS.

[0012] In some optional embodiments, the contaminant comprises 1,4-dioxane.

[0013] In some optional embodiments, the conditioning agent comprises an additive selected from one or more of the group: a polymer, a surfactant, an adsorbent, and an ion exchange resin.

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

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

[0016] In some optional embodiments, the modifier is an adsorbent selected from one or more of the group of organic and inorganic adsorbents, such as one or more of the group of powdered activated carbon (PAC), granular activated carbon (GAC), carbon black, silica, and activated alumina.

[0017] In some options, the moderator is a chiller or heat transfer device that reduces the temperature of the mixture of raw liquid and moderator.

[0018] In some options, the conditioned solution is held in an equalization tank for a period of time before being delivered to the flow-through electrochemical reactor.

[0019] In some optional embodiments, the period is between 30 seconds and 60 minutes, for example, between 2 minutes and 60 minutes.

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

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

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

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

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

[0025] In some optional configurations, the electrochemical reactor may include multiple electrode pairs.

[0026] In some optional configurations, the electrochemical reactor may include 1 to 10 pairs of electrodes.

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

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

[0029] In some optional embodiments, at least one of the first and second electrodes is a cathode comprising either titanium, titanium metal or titanium oxide, and either solid or mesh.

[0030] In some optional configurations, the first and second electrodes are concentrically arranged, with the first electrode including an anode located within the cylindrical wall of the second electrode including the cathode. In other optional configurations, the first and second electrodes may be inverted, with the second electrode including a cathode, the first electrode including an anode concentrically arranged, and the second electrode (cathode) located within the cylindrical wall of the first electrode (anode).

[0031] In another optional form, the solution flow paths extend at least partially within the anode, longitudinally along the anode longitudinal axis, and at least partially radially outwardly through the walls of the anode substantially perpendicular to the anode longitudinal axis.

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

[0033] In another optional aspect, the flow-through electrochemical reactor can include a power source connected to the first electrode and the second electrode.

[0034] In another optional aspect, the flow-through electrochemical reactor may include an inlet cap at a first end of the housing, the inlet cap aligning and maintaining the relative spacing between the first electrode and the second electrode.

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

[0036] In other optional forms, the second electrode can be 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-1of), mixed metal oxides (TiO 2 , RuO 2 , IrO 2 , and / or a combination of SnO with another metal oxide, typically titanium dioxide), boron doped diamond (BDD), or combinations thereof, for example, Magneli phase titanium oxide coated onto a supporting mesh made of stainless steel.

[0037] In another optional embodiment, the first electrode is a dimensionally stable anode (DSA), a Magneli phase titanium oxide (general formula Ti n O 2n-1 of), mixed metal oxides (TiO 2 , RuO 2 , IrO 2 , and / or a combination of SnO with another metal oxide, typically titanium dioxide), boron doped diamond (BDD), or a combination thereof. [Brief description of the drawings]

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

[0039] [Figure 1] 1 is a schematic representation of an electrochemical pollutant remediation system including a flow-through electrochemical reactor. [Diagram 2] 1 is a schematic representation of an alternative embodiment of an electrochemical pollutant remediation system including a flow-through electrochemical reactor. [Diagram 3] FIG. 3 is an exploded perspective view of an example of a flow-through electrochemical reactor that may be used in the electrochemical pollutant remediation system of FIG. 1 or FIG. 2. [Figure 4] FIG. 4 is a side view of the flow-through electrochemical reactor of FIG. [Diagram 5] FIG. 4 is a side cross-sectional view of the flow-through electrochemical reactor of FIG. [Figure 6]FIG. 4 is a close-up cross-sectional side view of the inlet cap of the flow-through electrochemical reactor of FIG. [Figure 7] FIG. 4 is a close-up cross-sectional side view of the outlet cap of the flow-through electrochemical reactor of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The electrochemical contaminant remediation systems and methods described herein advantageously remove contaminants from water quickly and efficiently. Moreover, the systems and methods described herein are particularly useful for remediating persistent contaminants, such as PFAS, which are believed to be chemically stable and have a substantially zero decay rate under ambient conditions.

[0041] Electrochemical remediation systems exist for the treatment of PFAS and other recalcitrant materials, but are limited by the mass transport of contaminants to the electrode surface. Once adsorbed and / or in close proximity to the electrode surface, these contaminants can undergo direct electron transfer reactions and then be partially or completely converted to components including, but not limited to, carbon dioxide, fluorides, and sulfates, reducing their environmental and human health hazards. However, the rate of contaminant destruction by existing systems and methods is very slow and inefficient.

[0042] The systems and methods described herein include a modifier to increase the mass transport rate of contaminants proximate to the electrode surface and / or the extent of adsorption to the electrode surface, thereby increasing the efficiency of the reactor, thereby reducing the throughput, performance, and / or electrical requirements, such as power and voltage, of the electrochemical reactor.

[0043] Turning now to FIG. 1 , an electrochemical contaminant remediation system 1000 is illustrated generally including an equalization tank 1020. The equalization tank 1020 has a raw liquid input 1030 and a conditioner input 1034. The equalization tank 1020 is configured to receive and contain raw liquid from the raw liquid input 1030 and a conditioner from the conditioner input 1034. The conditioner input 1034 is operatively connected to a source of conditioner 1036. The raw liquid and the conditioner are mixed and combined in the equalization tank 1020 to generate a conditioned solution in the equalization tank 1020. In some embodiments, the equalization tank 1020 may include a mixing device 1022, such as a mechanical mixer. In some embodiments, the mechanical mixer 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. 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.

[0044] As used herein, a conditioner typically refers to a material or mixture of materials used to form a conditioner / pollutant complex by charge neutralization, absorption, adsorption, or a combination thereof. More specifically, in the disclosed systems and methods, a contaminated liquid is cleaned or purified by a conditioner that forms a complex with the contaminants in the liquid. Thus, as used herein, a conditioner is a material that combines, complexes, adsorbs, interacts, and / or binds with contaminant molecules, typically PFAS. By combining with or binding to the contaminant molecules, the conditioner / pollutant complex gains increased insolubility, which allows the combined conditioner / pollutant molecules to more easily approach and / or more completely adsorb to the electrode surface. The adsorbed conditioner / pollutant molecules are then decomposed and destroyed by electrochemical reactions on or in proximity to the electrode surface.

[0045] In other embodiments, the conditioning agent may include heat transfer. For example, a cooling jacket 1099 may cool the conditioned liquid in the conditioning tank 1020. Although it is commonly understood that heat increases chemical reactions, the inventors have found that, counterintuitively, cooling the conditioned liquid enhances the destruction of contaminants (e.g., PFAS) in the flow-through electrochemical reactor 1010. In other embodiments, the raw liquid may be cooled by a chiller before being delivered to the mixing tank 1020. While cooling alone may increase the destruction of contaminants, the addition of a further conditioning agent to the disclosed cooling system and method for purifying contaminants in a liquid significantly increases the destruction of contaminants compared to cooling alone.

[0046] Conditioning agents useful in the devices and methods of the present disclosure can be divided into four basic classes: anionic polymers (e.g., polyanionic cellulose, or polyacrylamides that also contain acrylate monomer units), nonionic polymers (e.g., polyacrylamides), cationic polymers (e.g., polyquaterniums, also known as quaternary ammonium polymers, such as polyquaternium 6, (also referred to as polydiallyldimethylammonium chloride and polyDADMAC, and polyquaternium 7), and biopolymers, such as chitosan, sulfated glycosaminoglycans, non-sulfated glycosaminoglycans, hyaluronic acid chondroitin sulfate, dextran sulfate, glyceryl ... Polymers, including cationic surfactants (e.g., quaternary ammonium surfactants, such as cetonium bromide); high surface area materials (e.g., carbonaceous materials, such as carbon black or activated carbon, particularly powdered activated carbon (PAC), granular activated carbon (GAC), and / or carbon black, and inorganic adsorbents, such as silica or activated alumina); and ion exchange resins can be used to classify PFAS (and other contaminants) from liquids, such as water, by mixing the liquid containing the contaminant (e.g., PFAS) with a conditioner in an equalization tank to create a conditioned solution containing the contaminant / conditioner complex. More specifically, a conditioner such as a cationic polymer, an anionic polymer, a cationic surfactant, a high surface area adsorbent, or an ion exchange resin, e.g., polyDADMAC, cetrimonium bromide, PAC, and / or carbon black, is mixed with contaminant-containing water, such as PFAS-contaminated water.The moderators combine, complex, adsorb, interact, and / or bind with PFAS molecules (or other chemically stable, relatively soluble chemical contaminants) in the conditioning tank to form contaminant / moderator complexes that are theorized to be electrostatically attracted and more readily adsorbed and / or transported into close proximity to the electrode surface of the electrochemical reactor, thereby facilitating electron transfer from / to the contaminant and its electrochemical decomposition / destruction. Because electrostatic attraction is useful for forming complexes, positively charged moieties have been shown to have a significant effect on PFAS species, which are often negatively charged. It is believed that negatively charged moieties may have similar effectiveness at forming complexes with positively charged PFAS species.

[0047] A regulated fluid flow path 1040 fluidly connects the equalization tank 1020 to the flow-through electrochemical reactor 1010. In some embodiments, the regulated fluid flow path 1040 may include a pipe or conduit. In other embodiments, the regulated fluid flow path 1040 may include an open channel. An optional control valve 1024 may control the flow of regulated liquid through the regulated fluid flow path 1040. The control valve 1024 may be connected to a controller, such as a processor 1026, which sends a control signal to the control valve 1024 based on time measurements, user commands, and / or inputs from a sensor 1028 in the equalization tank 1020 and / or a sensor 1029 in the flow-through electrochemical reactor 1010 or a sensor downstream of the flow through the electrochemical reactor 1010 (not shown). The sensors 1028, 1029 may be wirelessly connected to the processor 1026 or the connection may be wired (not shown). If the control signal is based on a time period, the time period is sufficient to ensure adequate mixing of the conditioner with the untreated liquid. In general, any time period greater than 1 minute may be useful, although in practice long periods of mixing may be costly. In some embodiments, the time period may be between 30 seconds and 60 minutes, e.g., between 2 minutes and 20 minutes, depending on the size of the conditioner tank 2020, the amount of conditioner being mixed with the untreated liquid, and the reaction rate between the conditioner and the contaminant.

[0048] The conditioned fluid flow path 1040 is configured to receive the conditioned solution from the conditioning tank 1020 and deliver the conditioned 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 and creating an electroactive gap 1019 between the first electrode 1016 and the second electrode 1018. While the embodiment of FIG. 1 shows a single electrode pair (first electrode 1016 and second electrode 1018), other embodiments may include two or more electrode pairs within 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 within a single reactor housing 1012. Increasing the number of electrode pairs in the flow-through electrochemical reactor 1010 is one way to increase the throughput of the system. In the illustrated embodiment, the first electrode 1016 and the second electrode 1018 comprise flat plates separated by an electroactive gap 1019. In other embodiments described below, the first electrode 1016 and the second electrode 1018 may comprise hollow concentrically oriented cylinders. The conditioned solution passes through the electroactive gap 1019.

[0049] The untreated liquid contains the contaminant, and the modifier combines, complexes, adsorbs, interacts, and / or binds with the contaminant to produce a modifier / contaminant complex, which is advantageously electrostatically attracted to the surface of the first electrode 1016. This strategy is theorized to be particularly advantageous for contaminants such as PFAS, which have significant solubility in most solvents / solutions and therefore cannot be adsorbed and / or transported in close proximity to the electrode surface in significant quantities necessary to achieve effective treatment.

[0050] Turning now to Figure 2, another embodiment of an electrochemical contaminant remediation system 2000 is shown generally including an equalization tank 2020. Any of the features described in the embodiment of Figure 1 may be included in the embodiment of Figure 2. For example, the sensors 1028, 1029 described above may be incorporated in the embodiment of Figure 2, but are not shown or described for the sake of brevity.

[0051] The equalization tank 2020 has an untreated liquid input 2030 and a conditioning agent input 2034. The equalization tank 2020 is configured to receive and contain untreated liquid from the untreated liquid input 2030 and conditioning agent from the conditioning agent input 2034. The conditioning agent input 2034 is operatively connected to a source of conditioning agent 2036. The untreated liquid and conditioning agent are mixed and combined in the equalization tank 2020 to produce a conditioned solution in the equalization tank 2020. In some embodiments, the equalization tank 2020 may include a mixing device (not shown in FIG. 2 ), such as a mechanical mixer. In some embodiments, the mechanical mixer may include a rotating paddle, fan, 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 from a pump or other conveying device.

[0052] A regulated fluid pathway 2040 fluidly connects the regulation tank 2020 to a number of flow-through electrochemical reactors 2010a, 2010b, 2010c. In the embodiment of FIG. 2, the flow-through electrochemical reactors 2010a, 2010b, 2010c are connected in parallel with the liquid flow path 2040. Increasing the number of electrochemical reactors 2010a, 2010b, 2010c is another way to increase the throughput of the system. In any embodiment, more or fewer flow-through electrochemical reactors 2010a, 2010b, 2010c may be used. For example, 2, 4, 5, 6, or more flow-through electrochemical reactors may be used in the system. Additionally, some or all of the flow-through electrochemical reactors may be connected in series. In other embodiments, some flow-through electrochemical reactors may be connected in series and other flow-through electrochemical reactors may be connected in parallel. In some embodiments, two or more of the flow-through electrochemical reactors may be further enclosed within an optional external housing 2050, thereby potentially eliminating the need for individual regulated fluid paths 1040, 2040 to each electrochemical reactor 2010a, 2010b, 2010c. Additionally, in other embodiments, one or more of the reactor housings 2012 of the electrochemical reactors 2010a, 2010b, 2010c may include multiple electrode pairs.

[0053] 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. Similar to the embodiment of FIG. 1, at least one of the flow-through electrochemical reactors 2010a, 2010b, 2010c includes a housing 2012 having an internal liquid flow path 2014, a first electrode 2016 disposed within the internal liquid flow path 2014, and a second electrode 2018 spaced apart from the first electrode 2016 to create an electroactive gap 2019 between the first electrode 2016 and the second electrode 2018.

[0054] The conditioned solution passes through the electroactive gap 2019. The conditioned solution includes a contaminant and a conditioning agent that includes a material that combines, complexes, adsorbs, interacts, and / or binds with the contaminant to form a conditioning agent / contaminant complex that is electrostatically attracted to the surface of the first electrode 2016.

[0055] 3-7, there is shown one embodiment of a flow-through electrochemical reactor 10 that may be used in the electrochemical purification system described in FIGS. 1 and 2 above. The flow-through electrochemical reactor 10 includes a housing 12 having an internal liquid flow passage 14. A flow-through or solid first electrode, such as an anode 16, is disposed within the internal liquid flow passage 14. In the illustrated embodiment, the anode 16 is an annular shape, possibly a hollow cylinder, comprising a porous material. Advantageously, the flow-through electrochemical reactors described herein have no moving parts and are therefore relatively inexpensive and easy to manufacture while having a long service life. Additionally, the flow-through electrochemical reactors described herein can more efficiently treat contaminants present in the water / solution being treated with significantly less clogging and shorting compared to conventional electrochemical reactor devices.

[0056] A second electrode, such as a cathode 18, is spaced apart from the anode 16, thereby creating an electroactive gap 20 between the anode 16 and the cathode 18. In other embodiments, the concentric arrangement of the anode 16 and cathode 18 may be reversed.

[0057] Both the anode 16 and the cathode 18 in the flow-through electrochemical reactor illustrated in Figures 3-7 have a hollow cylindrical shape. In other embodiments, the anode 16 and the cathode 18 may have other shapes, such as flat plates or partial cylinders. In the embodiment of Figures 3-8, the anode 16 and the cathode 18 are arranged concentrically, with the anode 16 located within the cylindrical wall 22 of the cathode 18. The arrangement illustrated in Figures 3-7 may be used as an oxidation reactor, which is particularly advantageous for destroying PFAS. In other embodiments, the anode 16 and the cathode 18 may be reversed (such as by reversing the electrical connections, and thus the polarity of the applied current), such that the cathode 18 may be located within the cylindrical wall of the anode 16, for example, when used as a reduction reactor (such that the electron transfer reaction takes place on the cathode rather than the anode, i.e., the cathode is the working electrode). Nonetheless, the anode 16 and the cathode 18 may 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 via the inlet 26. As the conditioned solution fills the interior 24, it flows longitudinally parallel to the longitudinal axis x until it eventually reaches the bottom of the interior 24 where it is stopped by a plug 27. Once stopped, pressure builds up within the interior 24, which forces the conditioned solution to flow radially outward, perpendicular to the longitudinal axis x, through the walls of the anode 16.

[0058] The conditioned solution may flow through the porous openings of the anode, through the perforations of the anode 16, or around the anode through the walls of the anode 16. Nevertheless, once the conditioned solution flows through / around the walls of the anode 16, it enters the electroactive gap 20 within which a conditioned chemical reaction occurs, driven by the flow of electrons supplied by the charged anode and cathode. The conditioned solution continues to flow radially outward through the cathode wall 22, for example, through a number of openings 28 in the cathode wall 22. Once past the cathode wall 22, the conditioned solution flows within the annular space formed between the cathode 18 and the housing 12 toward the outlet 30.

[0059] In alternative embodiments, one or both of the anode 16 and cathode 18 may include solid cylindrical walls. In such embodiments, the internal liquid flow path may enter the hollow interior of the anode 16, flow downward until the plug 27 contracts, then flow around the lower end of the anode 16, flow through the gap between the bottom of the anode 16 wall and the plug 27, then flow upward through the electroactive gap 20 until it contacts the inlet cap 36, then flow through the gap between the inlet cap 36 and the top end of the cathode 18, and then flow down the outside of the cathode 18 to the outlet. In other alternative embodiments, the anode 16 or cathode 18 may include solid cylindrical walls, and the flow path may flow through the exterior surface of the solid cylindrical wall and through the electroactive gap 20.

[0060] A power source 34 is connected to the anode 16 and cathode 18 via electrical connections 32. Typically, the power source is a DC power source. However, an AC power source may alternatively be used if the AC power source is converted to DC in a transformer / rectifier. The power source 34 charges the anode 16 and cathode 18, and the conditioned solution fills the electroactive gap 20, causing electrons to flow between the anode 16 and cathode 18, driving a particular desired chemical reaction that results in the oxidation or reduction of the complexes formed, which is particularly advantageous for decomposing complexes that contain chemically stable and relatively soluble contaminants such as PFAS.

[0061] An inlet cap 36 is disposed at a first end 38 of the housing 12, where the inlet cap 36 maintains the 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 outlet flow from outside the cathode 18. The outlet guide flow cap 40 also cooperates with the plug 27 to seal one end of the interior 24 of the anode 24.

[0062] An adapter base inlet 44 is disposed at the first end 38 of the housing 12, the adapter base inlet 44 providing plumbing and electrical connections while maintaining a pressure seal.

[0063] In some embodiments, the cathode 18 is made of stainless steel, graphite or other carbonaceous material, a dimensionally stable anode (DSA), Magneli phase titanium oxide (general formula Ti n O 2n-1 For example, Ti 4 O 7 The term "Magneli phase titanium oxide" as used herein may include any of the following: a) a mixed metal oxide (RuO2 (ruthenium oxide), IrO2 (iridium oxide), SnO (tin oxide) and / or PtO2 (platinum oxide) in combination with another metal oxide, typically titanium dioxide), or boron doped diamond (BDD), or a combination thereof. As used herein, the term "Magneli phase titanium oxide" refers to a material having the general formula Ti n O 2n-1 Titanium oxide having, for example, Ti 4 O 7 , Ti 5 O 9 , Ti 6 O 11 In one embodiment, the Magneli phase titanium oxide refers to Ti 4 O 7 In other embodiments, the Magneli phase titanium oxide may be a mixture of Magneli phase titanium oxides.

[0064] The anode 16 is a dimensionally stable anode (DSA), a Magneli phase titanium oxide (general formula Ti n O 2n-1 , for example Ti 4 O 7 of), mixed metal oxides (e.g., RuO 2 (Ruthenium oxide), IrO 2 (iridium oxide), SnO (tin oxide) and / or PtO 2 (platinum oxide in combination with another metal oxide, typically titanium dioxide), boron doped diamond (BDD), others, or combinations thereof.

[0065] The anode 16 and / or the cathode 18 may further include a catalytic coating. The catalytic coating may be 1 μm to 30 μm thick, preferably 5 μm to 20 μm thick, and more preferably 10 μm to 20 μm thick. The catalytic coating may include a metal selected from one or more of the group of 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.

[0066] Once a suitable flow-through reactor has been constructed and arranged, power is applied to the cathode and anode and the conditioned solution is passed through the electrodes resulting in its electrochemical purification. The purified solution is then removed from the reactor. The applied power may be reversed periodically to prevent passivation of the electrodes and to remove contaminants. In this embodiment, the cathode is made of Magneli phase titanium oxide (general formula Ti n O 2n-1 (of) or other electrode materials. The reactor may be periodically backwashed or treated with acids or antiscalants to purge accumulated solids that may build up on the electrodes.

[0067] 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 passage 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 such that the inlet is located at the bottom and the outlet is located at the top (thus rotated 180 degrees relative to the illustrations shown in Figures 3-5). In such an arrangement, the electrochemically treated solution flows from bottom to top. In other embodiments, the anode and cathode may be reversed as described above.

[0068] According to any embodiment, the flow-through reactor may optionally further include an oxidation-reduction potential sensor, a pH sensor, a chlorine sensor, a conductivity sensor, a flow sensor, a pressure sensor, a temperature sensor, one or more contaminant sensors (ammonia, TOC, UV-Vis, etc.), or combinations thereof.

[0069] As explained above, one contaminant that may be advantageously reduced, removed, and / or destroyed by the electrochemical contaminant remediation systems and flow-through electrochemical reactors described above is PFAS.

[0070] As described above, the moderator is combined or bound with the PFAS molecules (or other chemically stable and relatively soluble chemical contaminants) in the conditioning tank to form contaminant / moderator complexes. The conditioned solution is delivered to the flow-through electrochemical reactor via the conditioned solution flow path. A current is applied to the flow-through electrochemical reactor to generate 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 / moderator bound complexes located in the electroactive gap are electrostatically attracted to the first electrode surface. The contaminant / moderator complexes have increased electrostatic attraction / adsorption to the electrode surface in the flow-through electrochemical reactor compared to the PFAS (or other chemically stable and relatively soluble chemical contaminant) molecules alone. In other words, the moderator enhances the transport of the contaminant / moderator complexes to the electrode surface. At least some of the contaminant / moderator bound complexes are adsorbed and / or electrostatically attracted such that they are in close proximity to the first electrode surface. The contaminant / modulator binding molecule is typically electrochemically destroyed on and / or in close proximity to the first electrode surface by direct transfer of electrons from the contaminant to the anode.

[0071] The conditioned solution may be held in the conditioning tank for a period of time before delivery to the flow-through electrochemical reactor to ensure proper mixing and formation of the contaminant / conditioner complex. In some embodiments, a suitable period of time is between 30 seconds and 60 minutes, e.g., between 2 minutes and 20 minutes.

[0072] The electrochemical contaminant remediation systems and flow-through electrochemical reactors described herein are advantageously used for water treatment, including, but not limited to, removing contaminants such as PFAS from industrial wastewater streams and from municipal treatment plants to produce drinking water. The flow-through electrochemical reactors described herein are durable and scalable to meet relatively small-scale personal or household needs, and relatively large-scale consumer, commercial, municipal or industrial needs.

[0073] 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, the entirety of which is incorporated herein by reference.

[0074] As used herein, "about," "approximately," or "substantially" means within an acceptable deviation of the particular value, inclusive of the stated value, as determined by one of ordinary skill in the art, taking into account the measurement in question and the error associated with the measurement of the 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.

[0075] As used herein, "carbonaceous" refers to a material that contains carbon. As used herein, to be considered "carbonaceous", a material must contain carbon with a carbon atom in other than the +4 oxidation state (so that the carbon atom can be oxidized). For example, carbonaceous materials include, but are not limited to, graphite, graphene, fullerenes, conductive plastics, and diamond.

[0076] As used herein, a "flow-through" anode or cathode refers to an anode or cathode electrode through which liquid can flow. Some non-limiting examples of flow-through electrodes include anodes or cathodes that have an internal through passage and / or contain perforations, pores, or holes through which liquid can flow. The holes can be manufactured in the electrode, for example, by punching. In one example, a solid but hollow cylindrical electrode can have an internal through passage through which liquid can flow axially along the length of the hollow cylindrical electrode. Other non-limiting examples include anodes with material walls that include a porous material, for example, hollow cylindrical anodes or cathodes with material walls that include a porous material through which liquid can flow axially along the length of the anode or cathode as well as laterally through the cylindrical anode or cathode walls. Porous electrodes, for example, porous Magneli phases, for example, Ti 4 O 7 The anode is generally preferred in that it provides a high surface area and increased contact with the water / solution (typically water) being electrochemically treated. Solid plate type anodes (not hollow and having no internal flow-through pathways) may also be used. Thus, both the anode and cathode may be flow-through or solid.

[0077] For any electrochemical process to operate, there must be two (or more) electrodes that function as an anode and a cathode. As used herein, "electroactive gap" refers to the gap or space between the electrodes that function as an anode and a cathode. In the disclosed flow-through electrochemical reactor, the electroactive gap is contained within a flow path through which a solution, typically the aqueous phase to be treated, can flow and electrons can transfer when power is applied to the electrodes of the electrochemical reactor. The flow of electric current can cause various chemical reactions within the electroactive gap that decompose and / or inactivate contaminants in the water / solution to be treated, thereby purifying the water to convert non-potable water to potable water, and / or purifying the wastewater stream, thereby allowing it to be discharged into the environment.

[0078] As used herein, a "dimensionally stable anode" refers to an anode that exhibits relatively high electrical conductivity and corrosion resistance. Generally, a dimensionally stable anode is made of RuO 2 (Ruthenium oxide), IrO 2 (iridium oxide), SnO (tin oxide), or PtO 2 It is made from one or more metal oxides, such as platinum oxide.

[0079] "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 metal oxides. One metal oxide is usually RuO, which both conducts electricity and catalyzes the desired reaction in situ, such as the production of chlorine gas. 2 (Ruthenium oxide), IrO 2 (iridium oxide), SnO (tin oxide) or PtO 2 (platinum oxide), or a combination thereof. The other metal oxide is typically titanium dioxide, which does not significantly conduct or catalyze, but does prevent internal corrosion.

[0080] The following examples are provided to illustrate the systems and methods for purifying contaminants in liquids disclosed herein.

[0081] Example 1 To test the effect of cationic polymers on the electrochemical remediation of PFAS, two different polymers were evaluated. The first (C-591) is poly(diallyldimethyl)ammonium chloride (poly(DADMAC)) and the second, C-577, is another polyquaternary amine.

[0082] Tests were carried out using leachate collected from a centralised water treatment plant which handles several different leachates. Due to the high organic matter levels in the water, raw leachate was not tested, but rather collected after treatment by coagulation and clarification with ferric chloride and lime.

[0083] For evaluation, the polymer was added to 3 gallons of leachate and then mixed for 15 minutes. After this, the polymer was dissolved in water and the porous titanium dioxide (Ti 4 O 7 Water was introduced into the reactor using a 3V anode and titanium metal mesh cathode and recirculated above 3V for 6 hours. Water samples were collected at 2, 4, and 6 hours and sent for PFAS analysis via EPA Method 1633. Two tests were performed with added polymer and a control test with no added polymer was also performed.

[0084] After the results were obtained, the first order kinetic decay rate for PFAS reduction was determined. First order kinetic decay (min -1 ) constants are as follows: [Table 1]

[0085] These results show that the addition of modifiers to the untreated liquid, and in particular the addition of cationic polymers, favorably and significantly improved the destruction of PFAS by approximately 300%, compared to electrochemical treatment alone (under the same operating conditions), by mixing the modifiers and contaminants, particularly PFAS, in the liquid.

[0086] All documents cited herein, including any cross-referenced or related patents or applications, and any patent applications or patents to which this application claims priority or benefit, are incorporated herein by reference in their entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein, or that it alone, or in any combination with any other reference or references, teaches, suggests, or discloses any such invention. Furthermore, to the extent that any meaning or definition of a term in this specification conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this specification shall control.

[0087] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended in the appended claims to cover all such changes and modifications that are within the scope of this invention.

Claims

1. 1. An electrochemical contaminant remediation system comprising: an equalization tank including an untreated liquid input and a modifier input, the equalization tank configured to receive untreated liquid from the untreated liquid input and modifier from the modifier input, such that the untreated liquid and the modifier mix and combine in the equalization tank to generate a conditioned solution; a regulated fluid flow path fluidly connecting the equalization tank to a first flow-through electrochemical reactor, the regulated fluid flow path configured to receive the regulated solution from the equalization tank and deliver the regulated solution to the flow-through electrochemical reactor, the first flow-through electrochemical reactor comprising: a housing including an internal fluid flow path; a first electrode disposed within the internal liquid flow path; a conditioned flow path including a second electrode spaced apart from the first electrode creating an electroactive gap between the first electrode and the second electrode, the conditioned solution passing through the electroactive gap; An electrochemical contaminant remediation system, wherein the untreated liquid includes a contaminant, the modifier combines with the contaminant to form a contaminant / modifier complex, and the contaminant / modifier complex is electrostatically attracted to a surface of the first electrode.

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

3. 3. The electrochemical pollutant remediation system of claim 1 or 2, wherein the conditioning agent comprises an additive selected from one or more of the group: polymers, surfactants, adsorbents, and ion exchange resins.

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

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

6. 3. The electrochemical pollutant remediation system of claim 1 or 2, wherein the conditioning agent comprises an anion exchange resin.

7. 10. The electrochemical pollutant remediation system of claim 1, further comprising a controllable valve between said equalization tank and said flow-through electrochemical reactor.

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

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

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

11. The electrochemical pollutant remediation system of claim 1 further comprising a mixing device within the equalization tank.

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

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

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

15. 1. A method for removing contaminants from a liquid, the method comprising: mixing the contaminant-containing liquid with a conditioner to produce a conditioned solution containing a contaminant / conditioner bound 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 one another by an electroactive gap; electrostatically attracting at least some of the contaminant / modifier bound complexes located within the electroactive gap to a first electrode surface; and electrochemically destroying contaminant / modifier binding molecules on or adjacent to said first electrode surface.

16. The method of claim 15 , wherein the contaminants include PFAS.

17. 16. The method of claim 15, wherein the conditioning agent comprises an additive selected from one or more of the group: 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. 16. The method of claim 15, wherein the conditioner comprises an adsorbent selected from one or more of the group: 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. 16. The method of claim 15, wherein mixing the contaminant-containing liquid with the conditioning agent occurs in an conditioning tank prior to delivering the conditioned solution to the flow-through electrochemical reactor.

22. 22. The method of claim 21, wherein the mixing is carried out for a period of from 30 seconds to 60 minutes, such as from 2 minutes to 20 minutes.

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