Electrochemical water desalination using organic mixed ion electron transporting materials

Abstract

An electrochemical water desalination system and method employing organic active electrode materials are disclosed. The system comprises a first electrode and a second electrode, each comprising an organic active material in contact with a current collector, arranged to define a flow channel for a saline feed solution therebetween. The organic active materials comprise conducting or semiconducting polymer films or molecular films, including polythiophenes, polypyrroles, polydiimides, polyfluorenes, polyisoindigos, polydiketopyroles, polyphenylenes, and copolymers thereof. The organic active materials remove ions from the feed solution by an intercalation mechanism, functioning as single-ion transporting intercalation materials for cations and anions respectively, providing the ion selectivity benefits of membrane capacitive deionization without requiring ion exchange membrane layers.

Description

Atty. Docket No.: 4997-00101ELECTROCHEMICAL WATER DESALINATION USING ORGANIC MIXED ION ELECTRON TRANSPORTING MATERIALSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 789,809, filed April 16, 2025, entitled "ELECTROCHEMICAL WATER DESALINATION USING ORGANIC MIXED ION ELECTRON TRANSPORTING MATERIALS," the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION

[0002] The present invention relates to the deionization or desalination of saline solution and more particularly to capacitive deionization or electrochemical water desalination systems and methods.BACKGROUND

[0003] Water scarcity is an important global issue . The number of water stressed regions is high and climbing, making potable water extraction from saline sources an attractive technology. Water usage also extends beyond direct human use with agriculture, livestock, and energy application comprising nearly 80% of the global water demand. Many techniques for water desalination exist including reverse osmosis, electrodialysis, multistage flash distillation, multieffect distillation, and mechanical vapor compression. These techniques are already being applied at scale to provide potable water to the most water stressed regions. Several key considerations must be taken into account when selecting a technology to provide potable water. Operating costs include the amount of energy required to produce a volume of water at reduced salinity, as well as the maintenance and replacement costs of materials and mechanical components used in the process. Initial capital expenditures also impact the feasibility of freshwater production and include the cost of equipment and facilities for a desalination plant.SUMMARY

[0004] In some embodiments, a capacitive deionization system is provided. The system comprises a first electrode comprising a first organic active material in contact with a first current collector, and a second electrode comprising a second organic active material in contact with a second current collector, wherein the first electrode and the second electrode define a flow channel therebetween.

[0005] In some embodiments, a method of deionization of a saline solution is provided. The method comprises providing the capacitive deionization system described above, generating aAtty. Docket No.: 4997-00101potential between the first electrode and the second electrode, flowing or otherwise introducing the saline solution between the first electrode and the second electrode, and absorbing ions in the saline solution into the first electrode and the second electrode to produce a reduced salinity solution.

[0006] In some embodiments, a method of deionization of a saline solution is provided. The method comprises providing a first electrode comprising a first organic active material in contact with a first current collector and a second electrode comprising a second organic active material in contact with a second current collector, wherein the first electrode and the second electrode define a flow channel therebetween, generating a potential between the first electrode and the second electrode, flowing or otherwise introducing the saline solution between the first electrode and the second electrode, and absorbing ions from the saline solution into the first organic active material and the second organic active material to produce a reduced salinity solution.

[0007] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:

[0009] FIG. 1 is a schematic illustration of an electrochemical water desalination system 100 according to some embodiments, showing a first current collector 102, a first organic active material layer 104, a saline solution flow channel, a second organic active material layer 106, and a second current collector 108.

[0010] FIG. 2a is a schematic of the coin cell, comprising titanium current collectors, activated carbon electrode layers, a PDMSZNaCl(aq) compartment, an Ag / AgCl reference electrode, and voltage measurement terminals VA and VB.

[0011] FIG. 2b is a graph showing the change in NaCl concentration in the activated carbon cell as a function of time for feed concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, and 1.0 g / L at an applied potential of 1 V.

[0012] FIG. 2c is a graph showing the integrated charge passing into the activated carbon electrodes as a function of time for the same feed concentrations.

[0013] FIG. 2d is a graph showing water desalination capacity (WDC, left axis, mg / g) and average desalination rate (ADR, right axis, mg / g / min) as a function of applied potential for feed concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, and 1.0 g / L.Atty. Docket No.: 4997-00101

[0014] FIG. 2e is a graph showing charge efficiency (A, %) as a function of applied potential for the same feed concentrations.

[0015] FIG. 2f is a graph showing invested desalination energy (IDE, kWh / mol) as a function of applied potential for the same feed concentrations.

[0016] FIG. 2g is a graph showing Coulomb efficiency (r|\_Coulomb) as a function of applied potential for the same feed concentrations.

[0017] FIG. 3a is a schematic of the coin cell, comprising titanium current collectors, a ProDOT electrode layer, a PEDOTPSS electrode layer, a PDMSZNaCl(aq) compartment, an Ag / AgCl reference electrode, and voltage measurement terminals VA and VB.

[0018] FIG. 3b is a drawing showing the chemical structure of PEDOTPSS.

[0019] FIG. 3c is a drawing showing the chemical structure of ProDOT.

[0020] FIG. 3d is a graph showing the change in NaCl concentration as a function of time for a feed concentration of 0.1 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0021] FIG. 3e is a graph showing the integrated charge (mC) as a function of time for a feed concentration of 0.1 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0022] FIG. 3f is a graph showing the change in NaCl concentration as a function of time for a feed concentration of 0.5 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0023] FIG. 3g is a graph showing the integrated charge (mC) as a function of time for a feed concentration of 0.5 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0024] FIG. 3h is a graph showing the change in NaCl concentration as a function of time for a feed concentration of 1.0 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0025] FIG. 3i is a graph showing the integrated charge (mC) as a function of time for a feed concentration of 1.0 g / L at applied potentials of 0.6 V, 0.8 V, and 1.0 V.

[0026] FIG. 3j is a graph showing water desalination capacity (WDC, left axis, mg / g) and average desalination rate (ADR, right axis, mg / g / min) as a function of applied potential for feed concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, and 1.0 g / L.

[0027] FIG. 3k is a graph showing charge efficiency (A, %) as a function of applied potential for the same feed concentrations.

[0028] FIG. 31 is a graph showing invested desalination energy (IDE, kWh / mol) as a function of applied potential for the same feed concentrations.

[0029] FIG. 3m is a graph showing Coulomb efficiency (r|\_Coulomb) as a function of applied potential for the same feed concentrations.Atty. Docket No.: 4997-00101

[0030] FIG. 4a is a schematic of the device structure incorporating an anion exchange membrane (AEM) disposed on the ProDOT electrode, comprising titanium current collectors, a ProDOT layer, an AEM layer, a PDMSZNaCl(aq) compartment, and a PEDOT:PSS layer.

[0031] FIG. 4b is a graph showing water desalination capacity (WDC, left axis, mg / g) and average desalination rate (ADR, right axis, mg / g / min) as a function of applied potential for the AEM device, for feed concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, and 1.0 g / L.

[0032] FIG. 4c is a graph showing charge efficiency (A, %) as a function of applied potential for the AEM device for the same feed concentrations.

[0033] FIG. 4d is a graph showing invested desalination energy (IDE, kWh / mol) as a function of applied potential for the AEM device for the same feed concentrations.

[0034] FIG. 4e is a graph showing Coulomb efficiency (r|\_Coulomb) as a function of applied potential for the AEM device for the same feed concentrations.

[0035] FIG. 4f is a schematic of the device structure incorporating a cation exchange membrane (CEM) disposed on the PEDOTPSS electrode, comprising titanium current collectors, a ProDOT layer, a PDMSZNaCl(aq) compartment, a CEM layer, and a PEDOTPSS layer.

[0036] FIG. 4g is a graph showing water desalination capacity (WDC, left axis, mg / g) and average desalination rate (ADR, right axis, mg / g / min) as a function of applied potential for the CEM device, for feed concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, and 1.0 g / L.

[0037] FIG. 4h is a graph showing charge efficiency (A, %) as a function of applied potential for the CEM device for the same feed concentrations.

[0038] FIG. 4i is a graph showing invested desalination energy (IDE, kWh / mol) as a function of applied potential for the CEM device for the same feed concentrations.

[0039] FIG. 4j is a graph showing Coulomb efficiency (r|\_Coulomb) as a function of applied potential for the CEM device for the same feed concentrations.

[0040] FIG. 5a is a schematic of the instrumentation configuration, showing the arbitrary function generator (AFG), Howland Current Source (HCS), lock-in amplifier (LIA), power amplifier (PA), transimpedance amplifier (HA), data acquisition system (DAQ), high-pass filter (HPF), low-pass filters (LPF), and voltage measurement terminals VA, VB, V+, V-, and GND.

[0041] FIG. 5b is a calibration curve showing measured solution conductance (mS) as a function of NaCl concentration (g / L), following the linear relationship G = 0.00854C.

[0042] FIG. 6a is a schematic showing the step-by-step fabrication process for PEDOTPSS films, comprising cleaning of the pristine substrate followed by spin-coating and annealing at 120°C to induce GOPS crosslinking.Atty. Docket No.: 4997-00101

[0043] FIG. 6b is a schematic showing the step-by-step fabrication process for ProDOT films, comprising cleaning of the pristine substrate, amine functionalization using APTMS, and subsequent PEGDE treatment to introduce PEG chains on the substrate surface prior to spincoating.

[0044] FIG. 6c is a step-height optical profilometry graph showing film height (pm) as a function of position (mm) for a PEDOTPSS film on an ITO-coated glass substrate.

[0045] FIG. 6d is a step-height optical profilometry graph showing film height (pm) as a function of position (mm) for a ProDOT film on an ITO-coated glass substrate.

[0046] FIG. 7a is a cyclic voltammogram of a PEDOTPSS film without a membrane layer, showing current (mA) as a function of applied potential (V vs. Ag / AgCl).

[0047] FIG. 7b is a cyclic voltammogram of a PEDOTPSS film coated with a cation exchange membrane (CEM), showing current (mA) as a function of applied potential (V vs. Ag / AgCl).

[0048] FIG. 7c is a cyclic voltammogram of a ProDOT film without a membrane layer, showing current (mA) as a function of applied potential (V vs. Ag / AgCl) for NaCl concentrations of 0.1 g / L, 0.5 g / L, and 1.0 g / L.

[0049] FIG. 7d is a cyclic voltammogram of a ProDOT film coated with an anion exchange membrane (AEM), showing current (mA) as a function of applied potential (V vs. Ag / AgCl) for NaCl concentrations of 0.1 g / L, 0.5 g / L, and 1.0 g / L.DETAILED ESCRIPTION

[0050] Thermal techniques like multistage flash distillation, multi-effect distillation, and mechanical vapor compression suffer from poor overall energy efficiency and are often used in regions where energy costs are low. These techniques also suffer from high initial capital expenditure, requiring equipment and vessels for controlling the temperature and pressure of the feed stream. Membrane based techniques like reverse osmosis are highly efficient, but also require equipment and vessels for the control of fluid pressure. In addition, the membranes through which the feed stream is driven can become fouled, leading to a decrease in the flow rate of the desalination system. These membranes must be replaced, taking portions of the desalination system offline, which requires that desalination plants are constructed with excess capacity, increasing the initial capital expenditure required.

[0051] Electrodialysis uses an electrochemical potential and membrane materials to separate saline water into a fresh water and brine stream. This technique is energy efficient and does not require the pressurization or depressurization of the feed stream, offering benefits with respect to the initial capital expenditure of a plant. However, a typical system configuration is complexAtty. Docket No.: 4997-00101and often requires consumable electrode materials in order to maintain the overall charge balance of the system.

[0052] In response to these challenges, electrochemical water desalination technologies which remove salt directly from the feed stream have emerged as a competitive technology. This technique, often referred to as capacitive deionization, uses an electrochemical potential applied between two electrodes to attract salt ions onto or into the electrode material, thereby removing it from the feed stream. The process is simpler to implement than other desalination techniques offering a benefit with respect to the initial capital expenditure required for the commissioning of a desalination plant. In a second step, some of the expended energy can be reclaimed as the device is discharged in the production of a brine stream. In general, capacitive deionization can operate at approximately ambient pressures, low temperatures, with relatively small cell voltages, allowing for inexpensive, scalable systems.

[0053] A variety of materials can be used in this application including activated carbon, carbon aerogels, carbon nanotubes, graphene, and mixtures thereof. However, the operating mechanism of these materials limits the mass of ions that can be removed per mass of the electrode material. These materials rely on the attraction of ions to the electrode surface where they form a thin ion rich layer, often described in terms of a Gouy-Chapman-Stem double-layer. Because ions cannot penetrate into the aforementioned carbonaceous materials, electrochemical water desalination technologies that rely on them are limited in their overall desalination capacity. Electrode materials with nanoscale pores are preferred in this context, but the tortuosity of ionically conductive pathways and necessity of electronic percolation throughout the electrode material limits the total exposed surface area that might be presented to the feed stream in the performance of water desalination.

[0054] More recently, attention has shifted towards inorganic materials like metal oxides which can incorporate ions into their bulk structure. The intercalation reaction which moves ions into the material bulk provides a clear advantage relative to impermeable electrode materials in that special care regarding material nanostructure need not be taken for the material to possess a large desalination capacity. As such, these materials possess higher desalination capacities than carbonaceous materials and benefit from less sensitive processing conditions. However, ceramic materials can be brittle and large area material deposition methods are not facile.

[0055] Researchers in the lab of the applicant have developed an electrochemical water desalination technology that employs conducting and semiconducting polymers as the active electrode materials. Polymeric materials are potentially inexpensive to produce, have water desalination capacities similar to metal oxide materials, and can take advantage of highAtty. Docket No.: 4997-00101throughput thin film fabrication techniques like roll-to-roll printing. As such, they offer several advantages in the production of desalinated water. The use of conducting polymers and other organic materials in water desalination technologies has some precedent, however, they have not been used as the primary active material, instead being employed as a binder or other material used in the creation of carbonaceous electrode materials.

[0056] Irrespective of the technique, the minimum energy required to produce fresh water is determined by the Gibbs free energy of separation. This is determined by the concentration of the feed solution, product solution, and brine solution, as well as the ratio between product and feed volumes. As stated above, an electrochemical desalination cell has the ability to recover stored energy in the second step of the process during which a brine stream is created, and electrode capacity is recovered. The total work necessary for desalination can approach the thermodynamic limit should the efficiency of both the charging step and the discharging step reach values comparable to state-of-the-art supercapacitors. This could potentially make it applicable for the desalination of seawater, a domain of applicability beyond its normal target of lower salinity sources like brackish water.

[0057] Disclosed herein is an electrochemical water desalination technology in which conducting or semiconducting polymers films comprise the active electrode materials. The active electrode materials may also be conducting or semiconducting molecular films. Hereafter, these films will be referred to as organic active layers. The organic active layers can be adhered to current collectors which can be composed on Ni, Ti, Cu, Ag, Au, stainless steel, carbon, or any combination thereof. The current collector can be in any suitable form such as a foil, plate, foam, mesh, or the like. The current collector allows for electrical contact to be made to the active electrode materials. The current collectors and active electrode materials disposed thereon can be collectively referred to as an electrode. The organic active layers change their charge state in the process of removing ions from a water stream to be desalinated.

[0058] The organic active layers remain intact and adhere to the current collector when placed into an aqueous solution. This can be accomplished by the formulation of active organic layers which are not water soluble or can be rendered water insoluble through crosslinking or other chemical reactions which change their solubility characteristics. As used herein, a substance is not water soluble when it does not dissolve in water to a significant extent, and, for example, remains identifiable even in the presence of water for an extended time period. These chemical changes can include the release of functional groups, for example, hydrophilic moieties attached to the electronically active portion of the system. The chemical changes can also include the attachment of hydrophobic functional groups which reduce the water solubility of the organicAtty. Docket No.: 4997-00101active layers. Other chemical changes can include the reaction of the active organic layers with the surface or incorporation of other surface chemistries which improve the physical or chemical adhesion of the organic active layers to the current collectors.

[0059] The current collectors can be coated with organic active layers using any suitable techniques such as an appropriate thin film deposition technique. These techniques can include spin-coating, dip-coating, drop-casting, flexographic printing, rotogravure printing, ink-jet printing, screen printing, offset printing, lithographic printing, sublimation, chemical vapor deposition, or heat transfer processes . Other processes such as pressing a thin film of the organic active layers can also be used. The resulting organic active layers can have a thickness of between about 50 nm and about 5 mm.

[0060] The current collectors, coated with organic active layers can be positioned proximally to one another with a spacing between organic active layers of 10 micrometres to 100 millimeters. The spacing between organic active layers can be enforced through a number of methods including the placement of materials between them. These materials can be designed in such a way to allow the flow of the feed stream between the electrodes or otherwise provide a means by which the feed stream can contact the organic active layers such that ions can be removed from the feed stream. The assembly of current collectors and organic active layers can be static during the desalination process or move relative to rigid components of the desalination equipment. For example, the current collectors coated with organic active layers could be flexible and passed from the feed stream to the brine stream continuously via a belt-driven mechanism.

[0061] The organic active layers can be designed to change their reduction or oxidation state to allow the uptake of ions from a feed solution. In order to remove positive ions, one organic active layer must be reduced and a second, opposing layer must be oxidized take up negative ions. This dual-action both completes the circuit and ensures local charge neutrality in the solution and the electrode materials. In the case where the organic active layer is in its neutral state, cation uptake is accompanied by reduction of the organic active layer, or anion uptake is accompanied by the oxidation of the organic active layer. In the case where the organic active layer is composed of cationic and anionic polymers, uptake of cations in the electrochemical water desalination process is accompanied by the reduction of the cationic species in the polymer or polymer composite. In the case where the organic active layer is composed of cationic and anionic polymers, uptake of anions in the electrochemical water desalination process is accompanied by the oxidation of the anionic portion of the polymer or polymer composite. Neutral organic active layers can include polythiophenes, polypyrroles, polydiimides, polyflourines, polyisoindigos, polydiketopyrrole, polyphenylenes, or any copolymers thereof. Organic active layers which areAtty. Docket No.: 4997-00101composed of cationic and anionic polymer composites or polymer blends can include the polymers listed above and further include polymers with sulfate, triflourosulfonoimide, triflate, borofluoride, nitrile, isonitrile, imidazolium, benzimidazolium, imide, fluorophosphate, carboxylate, or phosphate groups.

[0062] In addition, the use of the term “organic active layers” does not preclude the use of various additives such as metals in the polymer for structural reasons or to obtain the desired reduction and oxidation chemistry.

[0063] Compared to carbon based materials, the electrodes of the present disclosure may not require anion exchange layers such as membranes or coating to prevent the co-deposition, coadsorption, or co-incorporation of other ions. While not intending to be limited by theory, it is believed that the materials as disclosed herein result in the capture of the ions through an intercalation mechanism rather than the formation of an ionic double layer. As a result, the organic electronic materials function as single ion transporting intercalation materials, and as such, provide the benefits afforded by membrane electrochemical desalination devices without the need for additional membrane materials. This can result in a less expensive system by not including an ion exchange membrane (e.g., an anion exchange membrane or cation exchange membrane, etc.) on the active organic layers.

[0064] Figure 1 illustrates a deionization system 100 according to some embodiments. As shown a first electrode, formed from active organic material layer 104 and current collector 102, and a second electrode, formed from active organic material layer 106 and current collector 108, can be arranged to create a flow channel for a saline solution therebetween. In some aspects, a tab can be connected to the current collector 102 and / or current collector 108 to allow for an electrical connection to a system configured to provide a potential difference between the first electrode and the second electrode during use. A conduit can be used to supply the saline solution, which can be flowed or cycled through the electrodes. Flow through the channel can be a single pass or flow as a recycled solution until a desired level of salt removal is achieved. The system can be placed within a larger housing to provide a leak proof system.

[0065] In some aspects, the current collectors 102, 108 can be constructed similarly such as being formed from the same materials. In other embodiments, the current collectors 102, 108 may be different materials and / or forms. In some aspects, the composition, thickness, or application of the active organic material 104 and active organic material 106 can be the same or different. For example, a composition of the active organic material may vary depending on whether or not the active organic material is being used with the anode or cathode during the desalination process, as the different electrodes absorb different ions from the solution being desalinated. WhenAtty. Docket No.: 4997-00101different materials are used, the thickness and amounts may vary to provide the desired capacity for each electrode based on the differences in material compositions.

[0066] In use, the system 100 can operate by creating a potential difference across the electrodes while the saline solution is flowing or in contact with the electrodes. For example, the aqueous solution can comprise a brine such as seawater. The electrodes can include those described herein and include an active organic material coated onto a current collector. When the potential has been applied to the electrodes, positive and negative ions in the solution migrate to their respective counter-charged electrodes. They then absorb into the organic active material and can be held in place via an electrostatic attraction. This process can be carried out up of the saturation point of the organic active material to remove ions (e.g., salt) from the aqueous solution until a desired level of desalination is achieved. The resulting water can then be used for various uses such as drinking water.

[0067] This absorption mechanism is reversible, and by reversing or zeroing the applied potential, the intercalated ions in the organic active material can be discharged back into a solution, allowing the electrodes to be regenerated and reused. The regeneration process can be used with a separate aqueous solution stream into which the intercalated ions can be rejected. For example, a similar saline solution can be used during the regeneration process to reject the ions back into the saline stream, which can then be returned or discharged back to the source. Once regenerated, the process can be repeated.

[0068] The number of electrodes used in the system can be selected to provide an ion absorption capacity suitable to desalinate a desired amount of water. Further, any number of systems 100 can be operated in a swing bed or cyclic fashion to provide a level of continuous operation for the desalination process.

[0069] In addition to the primary metric of overall energy efficiency, there are a number of secondary metrics and performance indicators for evaluating electrochemical desalination devices. We will focus on several in order to evaluate material performance. The water desalination capacity, WDC. historically referred to as the salt adsorption capacity, describes the relationship between the mass of salt removed from the feed stream and the mass of the electrode material used, providing a scaled measure of material effectiveness for salt removal. This measure can also be applied as the volume of (dry) active material instead of the mass. The average desalination rate, ADR, is simply the WDC divided by the cycle time and describes the kinetics of the desalination process without relying on a model of the dynamics. The charge efficiency, A, compares the moles of ions removed to the moles of electrons used in theAtty. Docket No.: 4997-00101desalinating current. This metric is useful in evaluating the presence of leakage currents across the device, Faradaic reactions with the solution, and the effects of co-ion adsorption. The latter decreases A because ions associated with the electrode are simply exchanged with ions in the feed stream, consuming charge without decreasing feed salinity. The Coulomb efficiency, / coulomb- describes the balance of charge injected into the active material during the desalination step with the charge obtained during the discharge step of the process. Finally, the invested desalination energy, IDE, describes the total energy expended during the process including both charging (salt removal) and discharging (brine production) steps. In the experiments described below, discharge occurs at zero applied potential, which by definition does not allow for energy recovery during the discharge step. However, a device in practical implementation is designed to perform electrical work during the discharge process.

[0070] The coin cell geometry used here is shown in fig. 2a. It is composed of a pair of Ti current collectors onto which activated carbon has been deposited. Between these electrodes a poly(dimethoxy silane) (PDMS) o-ring is placed, creating a watertight compartment into which the solutions under test can be introduced. The PDMS o-ring contains 4 embedded wires which provide a reference electrode and a solution conductivity probe. An Ag / AgCl reference electrode was created using a silver wire coated with an anion exchange membrane (Aemion, lonomr Innovations Inc.) to prevent silver ions from entering the solution under test. The solution conductivity probe is constructed of a Pt wire, serving as a current source, a Ti wire serving as a high-impedance voltage probe, and an additional Ti wire serving as a ground for the AC current. The frequency of the AC solution conductivity probe was 100 kHz, which allows them to be decoupled from the low frequency voltages and currents of the current collectors using high pass and low pass analog filters.

[0071] Fig. 2b displays the concentration of NaCl as a function of time in a cell using activated carbon electrodes. The concentration was obtained through a calibration of salt concentration and solution conductivity (FIG.. 5B). The NaCl concentration decreases as the device is charged, and returns to the baseline level upon device discharge. As such, the device does not produce a purified water volume but allows for an assessment of material performance under a reproducible and idealized set of conditions. This coin cell offers the additional benefit of enabling small amounts of material to be tested, a benefit particularly important in the development of novel electrode materials. A symmetric potential (± 0.5 V vs. Ag / AgCl) was applied to the electrodes during the charging step and the discharge was performed at short circuit (0.0 V vs. Ag / AgCl). The WDC value, displayed in fig. 2d., can be read from the change in NaCl concentration at theAtty. Docket No.: 4997-00101end of the charging step divided by the mass of the electrode material (activated carbon plus binder). The dynamics, as described by the ADR value (fig. 2d) reflect mass transport processes within the pore structure of activated carbon.

[0072] Fig. 2c displays the integrated current flowing into the cell. As expected, the dynamics bear a close, but imperfect resemblance to the change in cell concentration. Values of A, displayed in fig. 2e are less than unity and show a decrease with increasing salt concentration. This is typically interpreted as evidence of co-ion adsorption. Because ions remain on the material exterior, electrochemical double layer formation prompts the inclusion of co-ions within the pore structure. As mentioned above, this effect does not contribute to greater WDC. prompting researchers to place an anion exchange membrane material on the cathode and cation exchange membranes on the anode. This technology, referred to a membrane capacitive deionization, is effective at mitigating the effects of co-ion adsorption but increases complexity in device construction.

[0073] The IDE is shown in fig. 2f and is calculated by the extracted salt concentration at the end of the charging step (expressed in moles) divided by the expended energy, calculated in terms of expended charge and applied potential. Fig. 2g displays r / coulomb as extracted from the ratio of charge injected at the completion of the charging step to the charge recovered at the completion of the discharge.

[0074] Fig. 3 describes analogous results for a cell which uses pi-conjugated polymers as the active electrode materials. Specifically, the anode is PEDOT:PSS, known to transport cations as it electrochemically transitions from its as-received state comprising positively doped PEDOT, to a state comprising neutral PEDOT. The cathode is ProDOT, a good anion transporting material. This material is neutral in its as-received form and becomes positively charged upon the uptake of anions. Obtaining good film adhesion is an important challenge in this context; existing surface functionalization methods were used for PEDOT:PSS and a two step surface treatment was developed to compatibilize the Ti surface to ProDOT, as illustrated in Fig. 6. In the two-step treatment, the titanium substrate was first functionalized with amine groups using (3 -aminopropyl)trimethoxy silane (APTMS), followed by exposure to a polyethylene glycol) diglycidyl ether (PEGDE) solution to introduce PEG chains on the surface. The PEG chains facilitate entanglement with the oligo-ether side chains of the ProDOT backbone, significantly enhancing adhesion and ensuring film stability during repeated charge-discharge cycles.

[0075] With respect to the ion uptake mechanism, both materials were recently shown to uptake ions via a diffusion mechanism. Therefore, they are best thought of as organic analogues toAtty. Docket No.: 4997-00101inorganic intercalation materials. Figs. 3d, 3f, and 3h show the change in concentration upon the application of a potential symmetric about the Ag / AgCl reference. As with activated carbon, salinity within the coin cell first decreases, then returns toward the baseline when potential is removed and the device discharged. However, the return is not complete over the timescale of the measurement, this is consistent with previous observations that ion diffusion is slower during the discharge process, and may be influenced by the effects of charge trapping. It is important to note that the concentration within the cell is measured in a plane 1.5 mm distant from each electrode, such that short timescale dynamics also involve the motion of ions within the aqueous layer.

[0076] The left axis of fig. 3j displays WDC as a function of potential for several concentrations. The values demonstrate the ability of the device to remove ions from solution for a variety of applied potentials and feed stream salinities. Comparisons with activated carbon demonstrate the superiority of organic materials in this regard. While sodium is not of particular value, it is noted that this also demonstrates the ability of the system to extract ions of greater value from aqueous solutions, including but not limited to lithium.

[0077] Considerations of stoichiometry provide an estimate of the theoretical maximum WDC achievable by the all-polymer electrochemical water desalination cell. In the case of PEDOT:PSS, a ratio of 2 monomer units per unit of NaCl results in a theoretical maximum WDC of 45.3 mg / g, while a ratio of 3 monomer units per NaCl unit results in a theoretical maximum WDC of 30.2 mg / g. For ProDOT, a ratio of 2 monomer units per NaCl unit results in atheoretical maximum WDC of 42.4 mg / g, while a ratio of 3 monomer units results in a theoretical maximum WDC of 28.3 mg / g. The largest measured WDC in the examples described herein is approximately 33.8 mg / g, which falls within these theoretical ranges for both materials, indicating operation near the theoretical maximum at the highest measured concentrations and applied potentials. It should be noted that WDC is a property of the cell as a whole rather than of a single electrode material: because one electrode accepts cations and the other accepts anions, charge balance considerations require that the electrode with the smaller individual WDC dictates the overall WDC of the cell. This distinction should be considered when comparing WDC values across different electrode materials and cell configurations.

[0078] The right axis of fig. 3j displays ADR as a function of applied potential for several concentrations. This is directly related to the rate of ion diffusion, which includes the diffusion constant and the inverse square of the film thickness. The vertical ion diffusion constants have recently been reported for PEDOT:PSS and ProDOT as approximately 2 x 10-10cm2 / s andAtty. Docket No.: 4997-001016 X IO-11cm2 / s. respectively. Given a film thickness of approximately 250 nm for PEDOTPSS and approximately 150 nm for ProDOT, the estimated timescale of ion diffusion through the film thickness is approximately 1 second, consistent with the experimental observations.

[0079] Figs. 3e, 3g, and 3i display the time integrated current as a function of time. As with activated carbon, the data is similar, but not identical in appearance to the measured concentration within the cell. Comparing the injected charge and the decrease in concentration, we obtained A values of our cell (fig. 3k). The A of the device decreases with applied potential, which could indicate reactions between PEDOTPSS and dissolved oxygen in the feed solution, consistent with the known catalytic properties of this material . Improvements in film properties with respect to unwanted Faradaic reactions is an important research target which will likely yield improvements in A values.

[0080] Fig. 31 displays IDE values extracted from the injected charge and salt concentration within the cell. The energy used in desalination increases with respect to applied potential, possibly as a result of decreasing A values. This hypothesis predicts that the IDE is insensitive to solution concentration in a manner similar to the A, consistent with the observations. The hypothesis that the leakage currents which cause a decrease in A as a function of potential is further supported decreasing ri coulomb with respect to applied potential (Fig. 3m). At low potentials, this factor approaches unity, consistent with the hypothesis co-ion adsorption in PEDOTPSS and ProDOT is of limited importance.

[0081] In purely capacitive materials like activated carbon, the adsorption of co-ions into the pore structure of the material is correlated with poorer performance, especially at elevated feed solution concentrations. One strategy for mitigating this problem is the deposition of single ion conductors onto the capacitive material. It is not uncommon in the literature to describe PEDOTPSS and to a lesser extent, ProDOT as functionally similar to activated carbon. As such, one should expect an improvement in the performance of all-polymer electrochemical deionization cell through the incorporation of single ion conductors on the active layers of the device. If instead, the material operates via an intercalation mechanism, ion incorporation is coupled with charge injection, limiting the effects of co-ion adsorption. In this case, device performance would more likely be limited by Faradic reactions with dissolved oxygen and other species present in the feed solution. As such, the inclusion of single ion conductors will not positively influence device performance, especially with respect to the WDC and to a lesser extent the value of A.Atty. Docket No.: 4997-00101

[0082] To test which, if any, of the polymeric electrode materials is limited by co-ion adsorption, devices utilizing anion and cation transporting membranes were fabricated and measured (fig.4). The cation transporting membrane is a commercially availble fluorine free hydrocarbon polymer containing sulfonate groups (Pemion, lonomr Innovations Inc.) known to swell slightly in aqueous solutions. Fig. 4 b-e describe the results in terms of the afforementioned performance metrics. The results are largely unchanged within the experimental uncertainty of the measurement, indicating that anion transport in PEDOT:PSS is not a first-order effect in its performance as an active layer in capacitive desalination. In a complimentary fashion, ProDOT was coated with an anion exchange membrane (Aemion, lonomr Innovations Inc.) similar in structure to materials reported in the literature. As with PEDOT:PSS the use of a single ion conducting polymer does not strongly impact the performance metrics associated with electrochemical desalination. This also indicates that co-ion transport, this time in the form of cation transport in ProDOT, is not a first-order effect in this material. Taken in sum, this strongly suggest that the organic electronic materials function as single ion transporting intercalation materials, and as such, provide the benefits afforded by membrane electrochemical desalination devices without the need for additional membrane materials.

[0083] To summarize the above discussion, electrochemical water desalination (EWD) devices employing PEDOT:PSS and ProDOT were demonstrated using a custom six-electrode coin cell. The ability of the materials to remove NaCl in response to an applied potential was demonstrated in real time by following the solution conductivity. The cell demonstrates water desalination capacity (WDC) values which outperform capacitve-type activated carbon electrodes. The device current consumed in this process was integrated with respect to time to provide measurements of charge efficiency (A), invested desalination energy (IDE), and Coulomb efficiency (77 coulomb)- Devices compared favorably with activated carbon. The role of co-ion uptake in the performance of all-polymer devices was investigated by coating the electrodes with single-ion transporting membranes. Devices showed similar performance, eliminating co-ion transport into the film bulk as an important loss mechanism. The results highlight that polymer electrodes of this type operate via an intercalation mechanism. Overall, electronically conductive polymers are potentially useful as electrode materials in electrochemical desalination devices. Freshwater production is an important global issue, particularly to persons in water-stressed regions of the world. In some aspects, organic electronic materials can be of use in this context.

[0084] The conclusion that the organic electrode materials function as single-ion transporting intercalation materials is further supported by cyclic voltammetry (CV) measurements conductedAtty. Docket No.: 4997-00101on PEDOTPSS and ProDOT films with and without the appropriate single-ion conducting membrane layers, as shown in Figs. 7a-7d. PEDOTPSS films coated with a cation exchange membrane (Fig. 7b) produced voltammograms nearly identical to those obtained from uncoated PEDOTPSS films (Fig. 7a) across all measured NaCl concentrations of 0.1 g / L, 0.5 g / L, and 1.0 g / L. Similarly, ProDOT films coated with an anion exchange membrane (Fig. 7d) produced voltammograms nearly identical to those from uncoated ProDOT films (Fig. 7c). If anion cotransport in PEDOTPSS or cation co-transport in ProDOT were significant, one would expect substantial changes in the CV response upon application of the respective single-ion conducting membrane layers, particularly under positive applied potentials and at the highest electrolyte concentrations where co-ion adsorption effects would be most pronounced. The absence of such changes across both materials and all measured conditions is consistent with an intercalationtype doping mechanism and is inconsistent with a non-Faradaic double-layer mechanism. CV scans were recorded at a scan rate of 40 mV / s in NaCl electrolyte solutions, with electrolytes purged with nitrogen for 20 minutes prior to each measurement to mitigate oxygen interference, and data from the third scan cycle were reported.

[0085] PEDOTPSS (PH 1000) was procured from Ossila and used as-received. Ethylene glycol (EG) (99.8%), (3-glycidoxypropyl)trimethoxysilane (GOPS) (>98%), polyvinylidene fluoride (PVDF) (M.W. = 534,000), N,N-dimethylacetamide (DMAc) (99%), sodium chloride (>99.0%), (3 -aminopropyl)trimethoxy silane (APTMS) (98%), glacial acetic acid (99%), polyethylene glycol) diglycidyl ether (PEGDE), 2-propanol (IPA) (>99.7%), dimethyl sulfoxide (DMSO) (>99.9%), 4-dodecylbenzenesulfonic acid (DBSA) (>95%), and silver wire (diameter 0.5 mm, >99.9%) were obtained from Sigma-Aldrich and used as received. Solutions of PEDOTPSS which were subsequently spin-coated, were prepared by mixing 5% (v / v) EG, 1% (w / w) GOPS, and 0.0002% (w / w) DBSA. ProDOT(OE)-DMP powder was sourced from 1-Material and dissolved in chloroform (>99.8%) (Sigma-Aldrich). Platinum wire (diameter 0.5 mm, 99.95%) was obtained from Thermo Scientific, and hydrochloric acid (HC1) (36.5-38%) was sourced from VWR Chemicals. Anion exchange membrane (AEM) powder was obtained from Ionomer, and cation exchange membrane (CEM) was provided by the Holdcroft Lab. Titanium substrates were obtained from McMaster Carr and used following a polishing step with 30 pm lapping film.

[0086] A slurry of activated carbon (US mesh 40) in DMAc was prepared at a concentration of 25 g / L, incorporating PVDF (15 wt.% of activated carbon) as a binder. Titanium substrates (2 cm x 2 cm) were pre-treated via immersion in 15% HC1 at 60 °C for 1 hour, followed by thorough rinsing with deionized (DI) water and plasma cleaning for 10 minutes. The electrode slurry (0.5 mb) was drop-cast onto the cleaned titanium substrates, which were then dried at 120 °C in anAtty. Docket No.: 4997-00101ambient oven for 2 hours, followed by additional drying at 80 °C in a vacuum oven for 2 hours to ensure complete solvent evaporation. PEDOTPSS films were deposited onto titanium substrates for use in the desalination test cell. Titanium substrates (2.5 cm x 2.5 cm) were cleaned and subjected to 15% HC1 immersion at 60 °C for 1 hour, followed by DI water rinsing and plasma cleaning. PEDOTPSS was spin-coated at 3000 rpm on ITO and at 1000 rpm on titanium for 30 seconds (acceleration: 300 rpm / s), followed by annealing at 120 °C for 1 hour to induce GOPS cross-linking.

[0087] ProDOT films were fabricated using a surface adhesion enhancement strategy to avoid delamination, as illustrated in Fig. 6b. Substrates underwent identical cleaning process before immersion in 1% (w / v) APTMS in DI water for 1 hour, samples were rinsed and subsequently treated with a 15% (w / w) PEGDE aqueous solution for 10 minutes. Following additional rinsing, substrates were immersed in 25% (v / v) IPA for 10 minutes to remove residual reagents, rinsed, and dried under nitrogen. A ProDOT solution (30 g / L in chloroform) was spin-coated at 1000 rpm on titanium substrates for 30 seconds (acceleration: 300 rpm / s).

[0088] AEM and CEM solutions were prepared at 20 g / L in DMSO. AEM was spin-coated onto ProDOT films, while CEM was spin-coated on PEDOTPSS films at 1500 rpm for 60 seconds (acceleration: 350 rpm / s). Samples were subsequently annealed at 80 °C for 16 hours.

[0089] A custom six-electrode EWD apparatus enabled in-situ solution conductance measurements in parallel with constant voltage water desalination. A rectangular polydimethylsiloxane (PDMS) ring was fabricated using the SYLGARD 184 silicone elastomer kit (Dow Coming Corporation). An aluminum mold for the ring was created, allowing four wires to be positioned along a plane equidistant to the current collecting electrodes. Three wires were used to detect solution conductivity by sourcing current and measuring the voltage between the current source and a high impedance voltage probe. The probe was placed equidistant between the current source and a third wire, also titanium, used as the ground for the solution conductivity measurement. Between this wire and circuit ground a high pass filter was placed to prevent this electrode from interfering from the more slowly varying signals from EWD. Within the PDMS ring, a fourth electrode was placed, an Ag / AgCl electrode, used to reference potentials applied to the EWD electrodes. The device was assembled by pressing the PDMS ring between the titanium substrates coated with electrode material. Feed solutions were injected into the cell using a syringe, with a second syringe serving as the solution outlet. Solution was passed through the cell to ensure the removal of all air from the system. The system was also kept out of direct sunlight to ensure temperature stability of the cell.Atty. Docket No.: 4997-00101

[0090] An instrumentation schematic for the custom six-electrode electrochemical water desalination apparatus is shown in Fig. 5a. The solution conductivity measurement used an arbitrary function generator (Tektronix AFG1022C) to generate a sinusoidal waveform at a frequency of 100 kHz. This signal was supplied to a custom-built Howland Current Source (HCS) that generated an AC current at the platinum electrode. A lock-in amplifier (LIA) (Stanford Research Systems, model SR810) measured the voltage required to supply the current. A titanium wire placed midway between the platinum current source and the AC ground electrode served as a high-impedance voltage probe. The potential difference between the voltage probe and the AC ground was used to quantify the solution conductance, which was converted to NaCl concentration using the calibration relationship G = 0.00854C (Fig. 5b), consistent with Kohlrausch's law of independent ionic migration. A second arbitrary function generator (Tektronix AFG3022C) provided a step potential waveform for the desalination measurement, fed through a custom-built power amplifier (PA). Current flowing into the current collectors was measured using a transimpedance amplifier (TIA), with the output recorded by a Data Acquisition System (DAQ) (NI-PCI-4461). The PDMS cell had a total internal volume of approximately 1.0 mb. Each experiment began with injection of 4.0 m of feed solution, with excess collected from the outlet to ensure complete filling. Prior to each desalination measurement, solution conductance was monitored under open-circuit conditions until a stable plateau was reached, indicating thermodynamic equilibrium at the selected feed concentration.

[0091] Film thickness was characterized using optical step-height profilometry (Bruker Contour GT-K), as shown in Figs. 6c and 6d for PEDOTPSS and ProDOT, respectively. PEDOT:PSS films were approximately 250 nm thick and ProDOT films were approximately 150 run thick. Because the films were too thin (approximately 200 nm) for direct gravimetric measurement, electrode mass was determined by multiplying the measured film thickness by the electrode area exposed to solution (1.82 cm x 1.82 cm) and the solid-state film density. A dry film density of 1.1 g / mL was used for both undoped PEDOTPSS and ProDOT.

[0092] Having described various devices, compositions, systems, methods, and processes, certain aspects can include, but are not limited to:

[0093] In a first aspect, a system for extracting ions from an aqueous solution comprises: a first electrode comprising a first organic active material in contact with a first current collector; and a second electrode comprising a second organic active material in contact with a second current collector; wherein the first electrode and the second electrode define a flow channel therebetween.Atty. Docket No.: 4997-00101

[0094] A second aspect can include the system of the first aspect, wherein the first organic active material or the second organic active material comprises at least one polymer comprising: polythiophenes, polypyrroles, polydiimides, polyflourines, polyisoindigos, polydiketopyrrole, polyphenylenes, or any copolymers thereof.

[0095] A third aspect can include the system of the second aspect, wherein the first organic active material or the second organic active material comprises the at least one polymer with sulfate, triflourosulfonoimide, triflate, borofluoride, nitrile, isonitrile, imidazolium, benzimidazolium, imide, fluorophosphate, carboxylate, or phosphate groups.

[0096] A fourth aspect can include the system of any one of the first through third aspects, wherein the first current collector or the second current collector comprises: Ni, Ti, Cu, Ag, Au, stainless steel, carbon, or any combination thereof.

[0097] A fifth aspect can include the system of any one of the first through fourth aspects, wherein the first organic active material or the second organic active material are water insoluble.

[0098] A sixth aspect can include the system of any one of the first through fifth aspects, wherein the first electrode is positioned between about 10 micrometers to about 100 millimeters from the second electrode.

[0099] A seventh aspect can include the system of any one of the first through sixth aspects, wherein the first organic active material or the second organic active material comprises at least one additive.

[0100] An eighth aspect can include the system of any one of the first through seventh aspects, wherein the first organic active material comprises PEDO PSS, and wherein the second organic active material comprises ProDOT.

[0101] A ninth aspect can include the system of any one of the first through eighth aspects, wherein the first electrode and the second electrode do not comprise an ion exchange membrane disposed thereon.

[0102] In a tenth aspect, a method of deionization of a saline solution comprises: providing the system of the first aspect; generating a potential between the first electrode and the second electrode; flowing or otherwise introducing the saline solution between the first electrode and the second electrode; and absorbing ions in the saline solution into the first electrode and the second electrode to produce a reduced salinity solution.

[0103] An eleventh aspect can include the method of the tenth aspect, further comprising : removing or reversing the potential between the first electrode and the second electrode; and releasing the ions from the first electrode and the second electrode into the saline solution to produce an increased salinity solution.Atty. Docket No.: 4997-00101

[0104] A twelfth aspect can include the method of the tenth or eleventh aspect, wherein the first organic active material or the second organic active material comprises at least one polymer comprising: polythiophenes, polypyrroles, polydiimides, polyflourines, polyisoindigos, polydiketopyrrole, polyphenylenes, or any copolymers thereof.

[0105] A thirteenth aspect can include the method of the twelfth aspect, wherein the first organic active material or the second organic active material comprises the at least one polymer with sulfate, triflourosulfonoimide, triflate, borofluoride, nitrile, isonitrile, imidazolium, benzimidazolium, imide, fluorophosphate, carboxylate, or phosphate groups.

[0106] A fourteenth aspect can include the method of any one of the tenth through thirteenth aspects, wherein the first current collector or the second current collector comprises: Ni, Ti, Cu, Ag, Au, stainless steel, carbon, or any combination thereof.

[0107] A fifteenth aspect can include the method of any one of the tenth through fourteenth aspects, wherein the first organic active material or the second organic active material are water insoluble.

[0108] A sixteenth aspect can include the method of any one of the tenth through fifteenth aspects, wherein the first electrode is positioned between about 10 micrometers to about 100 millimeters from the second electrode.

[0109] A seventeenth aspect can include the method of any one of the tenth through sixteenth aspects, wherein the first organic active material or the second organic active material comprises at least one additive.

[0110] An eighteenth aspect can include the method of any one of the tenth through seventeenth aspects, wherein the first organic active material comprises PEDOTPSS, and wherein the second organic active material comprises ProDOT.

[0111] A nineteenth aspect can include the method of any one of the tenth through eighteenth aspects, wherein the first electrode and the second electrode do not comprise an ion exchange membrane disposed thereon.

[0112] A twentieth aspect can include the system of any one of the first through ninth aspects, wherein the first organic active material and the second organic active material remove ions from the saline solution by an intercalation mechanism.

[0113] A twenty-first aspect can include the system of the twentieth aspect, wherein the first organic active material functions as a single-ion transporting intercalation material for cations and the second organic active material functions as a single-ion transporting intercalation material for anions.Atty. Docket No.: 4997-00101

[0114] A twenty-second aspect can include the system of the first aspect, wherein the first organic active material or the second organic active material comprises a conducting or semiconducting molecular film.

[0115] A twenty-third aspect can include the system of any one of the first through twenty-second aspects, wherein the first organic active material or the second organic active material is deposited on the respective current collector by spin-coating, dip-coating, dropcasting, flexographic printing, rotogravure printing, ink-jet printing, screen printing, offset printing, lithographic printing, sublimation, chemical vapor deposition, or a heat transfer process.

[0116] A twenty-fourth aspect can include the system of any one of the first through twenty-third aspects, wherein the first organic active material or the second organic active material has a thickness of between about 50 nm and about 5 mm.

[0117] A twenty-fifth aspect can include the system of any one of the first through twenty-fourth aspects, wherein the first current collector or the second current collector is in the form of a foil, plate, foam, or mesh.

[0118] A twenty-sixth aspect can include the system of any one of the first through twenty-fifth aspects, wherein a surface of the first current collector or the second current collector is treated with a functionalized silane prior to deposition of the organic active material.

[0119] In a twenty-seventh aspect, a method of deionization of a saline solution comprises: providing a first electrode comprising a first organic active material in contact with a first current collector and a second electrode comprising a second organic active material in contact with a second current collector, wherein the first electrode and the second electrode define a flow channel therebetween; generating a potential between the first electrode and the second electrode; flowing or otherwise introducing the saline solution between the first electrode and the second electrode; and absorbing ions from the saline solution into the first organic active material and the second organic active material to produce a reduced salinity solution.

[0120] A twenty-eighth aspect can include the method of any one of the tenth through nineteenth aspects or the twenty-seventh aspect, wherein the first organic active material and the second organic active material remove ions from the saline solution by an intercalation mechanism.

[0121] A twenty-ninth aspect can include the method of any one of the tenth through nineteenth aspects or the twenty-seventh through twenty-eighth aspects, wherein a plurality of systems are operated in a swing-bed or cyclic fashion to provide continuous desalination.

[0122] A thirtieth aspect can include the method of any one of the tenth through nineteenth aspects or the twenty-seventh through twenty-ninth aspects, wherein the first organicAtty. Docket No.: 4997-00101active material or the second organic active material is deposited on the respective current collector by spin-coating, dip-coating, drop-casting, flexographic printing, rotogravure printing, ink-jet printing, screen printing, offset printing, lithographic printing, sublimation, chemical vapor deposition, or a heat transfer process.

[0123] Embodiments are discussed herein with reference to the Figures. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the systems and methods extend beyond these limited embodiments. For example, it should be appreciated that those skilled in the art will, in light of the teachings of the present description, recognize a multiplicity of alternate and suitable approaches, depending upon the needs of the particular application, to implement the functionality of any given detail described herein, beyond the particular implementation choices in the following embodiments described and shown. That is, there are numerous modifications and variations that are too numerous to be listed but that all fit within the scope of the present description. Also, singular words should be read as plural and vice versa and masculine as feminine and vice versa, where appropriate, and alternative embodiments do not necessarily imply that the two are mutually exclusive.

[0124] It is to be further understood that the present description is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses, and applications, described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present systems and methods. It must be noted that as used herein and in the appended claims (in this application, or any derived applications thereof), the singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "an element" is a reference to one or more elements and includes equivalents thereof known to those skilled in the art. All conjunctions used are to be understood in the most inclusive sense possible. Thus, the word "or" should be understood as having the definition of a logical "or" rather than that of a logical "exclusive or" unless the context clearly necessitates otherwise. Structures described herein are to be understood also to refer to functional equivalents of such structures. Language that may be construed to express approximation should be so understood unless the context clearly dictates otherwise.

[0125] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this description belongs. Preferred methods, techniques, devices, and materials are described, although any methods, techniques, devices, or materials similar or equivalent to those describedAtty. Docket No.: 4997-00101herein may be used in the practice or testing of the present systems and methods. Structures described herein are to be understood also to refer to functional equivalents of such structures. The present systems and methods will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings.

[0126] From reading the present disclosure, other variations and modifications will be apparent to persons skilled in the art. Such variations and modifications may involve equivalent and other features which are already known in the art, and which may be used instead of or in addition to features already described herein.

[0127] Although claims may be formulated in this application or of any further application derived therefrom, to particular combinations of features, it should be understood that the scope of the disclosure also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same systems or methods as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as do the present systems and methods.

[0128] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The Applicant(s) hereby give notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present Application or of any further Application derived therefrom.

Claims

Atty. Docket No.: 4997-00101CLAIMS1. A capacitive deionization system comprising:a first electrode comprising a first organic active material in contact with a first current collector; anda second electrode comprising a second organic active material in contact with a second current collector;wherein the first electrode and the second electrode define a flow channel therebetween.

2. The system of claim 1, wherein the first organic active material or the second organic active material comprises at least one polymer comprising: polythiophenes, polypyrroles, polydiimides, polyflourines, polyisoindigos, poly diketopyrrole, polyphenylenes, or any copolymers thereof.

3. The system of claim 2, wherein the first organic active material or the second organic active material comprises the at least one polymer with sulfate, triflourosulfonoimide, triflate, borofluoride, nitrile, isonitrile, imidazolium, benzimidazolium, imide, fluorophosphate, carboxylate, or phosphate groups.

4. The system of claim 1 , wherein the first current collector or the second current collector comprises: Ni, Ti, Cu, Ag, Au, stainless steel, carbon, or any combination thereof.

5. The system of claim 1, wherein the first organic active material or the second organic active material are water insoluble.

6. The system of claim 1, wherein the first electrode is positioned between about 10 micrometers to about 100 millimeters from the second electrode.

7. The system of claim 1, wherein the first organic active material or the second organic active material comprises at least one additive.

8. The system of claim 1, wherein the first organic active material comprises PEDOTPSS, and wherein the second organic active material comprises ProDOT.

9. The system of claim 1, wherein the first electrode and the second electrode do not comprise an ion exchange membrane disposed thereon.

10. The system of claim 1, wherein the first organic active material and the second organic active material remove ions from the saline solution by an intercalation mechanism.

11. The system of claim 10, wherein the first organic active material functions as a singleion transporting intercalation material for cations and the second organic active material functions as a single-ion transporting intercalation material for anions.

12. The system of claim 1, wherein the first organic active material or the second organic active material comprises a conducting or semiconducting molecular film.Atty. Docket No.: 4997-0010113. The system of claim 1, wherein the first organic active material or the second organic active material is deposited on the respective current collector by spin-coating, dipcoating, drop-casting, flexographic printing, rotogravure printing, ink-jet printing, screen printing, offset printing, lithographic printing, sublimation, chemical vapor deposition, or a heat transfer process.

14. The system of claim 1, wherein the first organic active material or the second organic active material has a thickness of between about 50 nm and about 5 mm.

15. The system of claim 1 , wherein the first current collector or the second current collector is in the form of a foil, plate, foam, or mesh.

16. The system of claim 1, wherein a surface of the first current collector or the second current collector is treated with a functionalized silane prior to deposition of the first organic active material or the second organic active material.

17. A method of deionization of a saline solution, the method comprising:generating a potential between the first electrode and the second electrode of the capacitive deionization system of claim 1 ;flowing or otherwise introducing the saline solution between the first electrode and the second electrode; andabsorbing ions in the saline solution into the first electrode and the second electrode to produce a reduced salinity solution.

18. The method of claim 17, further comprising:removing or reversing the potential between the first electrode and the second electrode;andreleasing the ions from the first electrode and the second electrode into the saline solution to produce an increased salinity solution with respect to one or more of the ions present.

19. The method of claim 17, wherein the first organic active material or the second organic active material comprises at least one polymer comprising: polythiophenes, polypyrroles, polydiimides, polyflourines, polyisoindigos, poly diketopyrrole, polyphenylenes, or any copolymers thereof.

20. The method of claim 19, wherein the first organic active material or the second organic active material comprises the at least one polymer with sulfate, triflourosulfonoimide, triflate, borofluoride, nitrile, isonitrile, imidazolium, benzimidazolium, imide, fluorophosphate, carboxylate, or phosphate groups.Atty. Docket No.: 4997-0010121. The method of claim 17, wherein the first current collector or the second current collector comprises: Ni, Ti, Cu, Ag, Au, stainless steel, carbon, or any combination thereof.

22. The method of claim 17, wherein the first organic active material or the second organic active material are water insoluble.

23. The method of claim 17, wherein the first electrode is positioned between about 10 micrometers to about 100 millimeters from the second electrode.

24. The method of claim 17, wherein the first organic active material or the second organic active material comprises at least one additive.

25. The method of claim 17, wherein the first organic active material comprises PEDOT:PSS, and wherein the second organic active material comprises ProDOT.

26. The method of claim 17, wherein the first electrode and the second electrode do not comprise an ion exchange membrane disposed thereon.

27. The method of claim 17, wherein the first organic active material and the second organic active material remove ions from the saline solution by an intercalation mechanism.

28. The method of claim 17, wherein a plurality of systems are operated in a swing-bed or cyclic fashion to provide continuous desalination.

29. The method of claim 17, wherein the first organic active material or the second organic active material is deposited on the respective current collector by spin-coating, dipcoating, drop-casting, flexographic printing, rotogravure printing, ink-jet printing, screen printing, offset printing, lithographic printing, sublimation, chemical vapor deposition, or a heat transfer process.

30. A method of deionization of a saline solution, the method comprising:providing a first electrode comprising a first organic active material in contact with a first current collector and a second electrode comprising a second organic active material in contact with a second current collector, wherein the first electrode and the second electrode define a flow channel therebetween;generating a potential between the first electrode and the second electrode; flowing or introducing the saline solution between the first electrode and the second electrode; andabsorbing ions from the saline solution into the first organic active material and the second organic active material to produce a reduced salinity solution.

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