Tunnel-structured ζ-V2O5 as a redox-active intercalation host for hybrid capacitive deionization

Abstract

A hybrid capacitive deionization cell (HCDI) using ζ-VO as a positive electrode is disclosed, as are devices and methods for using the HCDI cell using ζ-VO as a positive electrode for the desalination of aqueous solutions and / or the recovery of ions such as lithium, potassium, and sodium.

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 384,632, filed November 22, 2022, which is incorporated by reference herein in its entirety.

[0002] The present disclosure relates specifically to desalination devices and methods that include systems that use hybrid capacitive deionization cells (HCDIs) that include ζ-V2O5 nanowires as the positive electrode. [Background technology]

[0003] Much of the Earth's water has a salt content that is too high for edible or agricultural uses. Enhanced oil recovery operations produce large volumes of produced wastewater with high mineral content that can substantially exacerbate water scarcity. Current deionization methods, such as reverse osmosis, operate by removing water (the major phase) from salt (the minor phase) and are therefore extremely energy intensive. Furthermore, these methods are limited in their ability to selectively extract high-value ions from produced wastewater and brine streams.

[0004] Fresh water is a scarce commodity that is becoming increasingly valuable worldwide, and major recent efforts have focused on desalination of seawater, brackish water, and flowback and produced water (FPW) brought to the surface using hydraulic fracturing. Despite notable advances in membrane design and process intensification, many current desalination methods, such as reverse osmosis, multistage flash distillation, and direct solvent extraction, require excessively high energy budgets. Each of these methods removes the majority phase (water) from the minority phase (dissolved salt ions), requiring a large energy input to operate the selective transport process.

[0005] Furthermore, these methods have limited selectivity for certain high-value ions, such as lithium, transition metals, rare earth elements, and uranium, that are abundant in FPW and hold the key to new paradigms for resource recovery necessary for the energy transition.

[0006] FPW is also now viewed as a major environmental liability. Scanlon and colleagues estimate that in the Permian Basin, which stretches across Texas and New Mexico, FPW production from conventional and unconventional reservoirs increased by approximately 40×10 between 2005 and 2015, respectively. 9 bbl and 4x10 9 The recovery and reuse of FPW is challenging due to complications posed by its high salinity and the presence of enhanced oil recovery additives, while its reinjection into aquifers is increasingly regulated.

[0007] In conventional capacitive deionization (CDI) methods, dissolved ions are removed from brine by applying a potential across a deionization cell containing two high-surface-area carbon electrodes. In this process, dissolved ions migrate to a charged interface, forming an electric double layer of solvated ions, with the concentration of stored ions directly proportional to the accessible surface area of ​​the electrode. Several improvements have been made to improve the effectiveness of CDI cells, such as the implementation of electrodes with hierarchical porosity to increase the surface area available for ion adsorption and the addition of ion-exchange membranes to prevent the diffusion of counterions. While recent innovations have improved the capacity and efficiency of CDI cells, a fundamental drawback of this approach is that ion storage is limited to the electric double layer formed on the wetted surface of the electrode material, which remains a substantial limitation.

[0008] Hybrid capacitive deionization (HDCI) stores ions in the internal volume of a material through a redox reaction similar to that of the cathode material in Li-ion batteries. Selectivity in ion extraction arises based on differences in the insertion potential, bulk diffusion coefficient, and interstitial site preference of various ions. Therefore, hybrid capacitive deionization methods hold great promise for not only enabling the reuse of FPW in hydraulic fracturing operations, but also for enabling the extraction of high-value ions with high selectivity.

[0009] Similar considerations regarding surface versus bulk ion storage explain the crucial difference between the operating mechanisms of supercapacitors and intercalation batteries. In the positive electrodes of Li-ion batteries or other intercalation batteries, ions are stored in interstitial sites within the bulk of the electrode material based on a simultaneous redox reaction. The crucial difference between HCDI and CDI is the action of a galvanic reaction in the former, which leads to the formation of an electric double layer as well as interfacial desolvation and bulk diffusion of ions. Storing ions in interstitial sites, rather than just in a surface double layer, leads to a significant increase in charge storage capacity. A notable tradeoff is the slower removal rate of intercalation electrodes, resulting from diffusion limitations at the interface and the action of galvanic processes.

[0010] This disclosure demonstrates that these limitations can be substantially alleviated through appropriate structuring of electrode tortuosity, control of crystallite size, and alteration of the structure and composition of the intercalation host. Insertion chemistry also provides a sensitive method for differentiating between the uptake of various ions from aqueous media based on differences in bulk diffusion coefficients and intercalation potentials, which are determined by the crystal lattice-dependent size of the interstitial sites, the migration barriers between sites, and the thermodynamics of the insertion reaction. Specifically, to overcome the challenges in the recovery and reuse of FPW (or other saline waters) and the shortcomings associated with prior art methods, this disclosure describes an electrochemical approach for desalination and selective ion capture based on the sequestration of ions within the 1D tunnels of ζ-VO, a versatile intercalation host for monovalent and multivalent ions.

[0011] Not all of the subject matter described in the Background is necessarily prior art, and it should not be assumed to be prior art merely as a result of its description in the Background section. Along these lines, any awareness of prior art problems described in the Background or related to such subject matter should not be treated as prior art unless expressly stated to be prior art. Instead, the discussion of any subject matter in the Background should be treated in its own right and as part of the inventor's approach to a particular problem, which may also be inventive in its own right. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent Publication No. 2020 / 0321614 [Non-patent literature]

[0013] [Non-Patent Document 1] Marley, PM; Abtew, TA; Farley, KE; Horrocks, GA; Dennis, RV; Zhang, P.; Banerjee, S., Emptying and filling a tunnel bronze. Chemical Science 2015, 6 (3), pp. 1712~1718 Summary of the Invention [Means for solving the problem]

[0014] The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. This summary is not an exhaustive overview of the disclosure. It is not intended to identify key features or critical elements of the disclosure, nor is it intended to delineate the scope of the disclosure. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0015] The following describes ζ-V2O5 (zeta-vanadium(V) oxide) with tunnel structures as a redox-active intercalation host for hybrid capacitive deionization useful in desalination devices, apparatus, and methods.

[0016] Specifically, hybrid capacitive deionization (HDCI) cells utilizing tunnel-structured ζ-VO as a redox-active cathode material have been shown to overcome many of the challenges associated with the prior art. By increasing surface adsorption through a current-induced insertion process, a 50% improvement in ion removal capacity for K and Li ions is achieved compared to high-surface-area capacitive carbon electrodes. Extracted ions are accommodated in interstitial sites within the 1D tunnel framework of ζ-VO. The ion removal kinetics depends on the free energy of hydration, which determines the ease of desolvation at the electrode / electrolyte interface. The overall ion removal capacity is primarily a function of the solid-state diffusion coefficient of the ions. ζ-VO cathodes are able to remove Li from a mixed flow stream. + It shows substantial selectivity for the removal and enrichment of Li ion concentrations from produced wastewater from the Permian Basin.

[0017] ζ-VO is a polymorph with a 1D tunnel structure of VO and is used in this disclosure as a cathode material for HCDI. Its abundance of interstitial sites, accessibility of multi-electron redox at the vanadium center, low diffusion barrier for ion migration between sites, ability to insert various cations, and excellent stability in aqueous media make it highly advantageous for desalination methods. This disclosure specifically addresses the desalination of Li from aqueous media, including any aqueous media with a salinity greater than 1000 ppm. +, Na + , and K + We describe the construction and implementation of an HCDI cell based on a ζ-VO active electrode for ion sequestration. The sequestration involves the placement of cations within the 1D tunnels of ζ-VO, not only by adsorptive but also by intercalative means. Furthermore, differences in site preferences, hydration radii, and hydration free energies enable ion selectivity from mixed ion streams.

[0018] An embodiment of the present disclosure is an HDCI cell that includes a positive electrode material containing ζ-VO, a current collector, a cation exchange membrane, a separator layer, an anion exchange membrane, and a negative electrode material. The HDCI cell may include a Delrin exterior. Additionally, the positive electrode ζ-VO can be modified by, for example, substituting molybdenum, tungsten, or niobium for one or more vanadium sites to change the ion selectivity of the electrode material.

[0019] Embodiments of the present disclosure include a method comprising electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode in an aqueous solution having a salt concentration greater than 1000 ppm, and removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution. Preferably, the method has a selectivity for removing lithium ions over other ions of 10 to 10. 6 Lithium ions are removed from the aqueous solution within a factor of 10.

[0020] Embodiments of the present disclosure include methods that include electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode in an aqueous solution having a salt concentration greater than 1000 ppm, removing lithium ions from the aqueous solution, and electrochemically cycling the HDCI cell for selective removal of one or more other ions and removing those other ions.

[0021] Embodiments of the present disclosure include a method comprising electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode with an aqueous solution having a salt concentration greater than 1000 ppm and removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution, wherein each electrochemical cycle lasts for a time period between 10 seconds and 90 minutes.

[0022] Embodiments of the present disclosure include a method comprising electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode with an aqueous solution having a salt concentration greater than 1000 ppm and removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution, wherein the ζ-VO positive electrode has a thickness between 2 nm and 1000 μm.

[0023] An embodiment of the present disclosure includes a method comprising electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode with an aqueous solution having a salt concentration greater than 1000 ppm and removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution, wherein each step is performed at a temperature between 0°C and 95°C.

[0024] An embodiment of the present disclosure includes a method comprising electrochemically cycling an HDCI cell comprising a ζ-VO positive electrode with an aqueous solution having a salinity greater than 1000 ppm and removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution, wherein the aqueous solution comprises flowback, produced water, seawater, brackish water, geothermal brine, or synthetic brine. Preferably, the aqueous solution is one or more of flowback or produced water, and the method further comprises filtering the aqueous solution to remove residual oil and dissolved solids prior to electrochemical cycling.

[0025] An embodiment of the present disclosure includes an HDCI device for desalination in a remote location, including a conduit that can be attached to an aqueous solution storage tank, one or more additional conduits through which the aqueous solution can flow, a deoiling or sludge removal membrane connected to at least one of the conduits, a nanofiltration unit connected to at least one of the conduits and connected to an HDCI cell, and a vehicle or trailer, the HDCI cell including (i) a cathode material including ζ-VO, (ii) a current collector, (iii) a cation exchange membrane, (iv) a separator layer, (v) an anion exchange membrane, and (vi) an anode material. This embodiment may further include a unit for precipitating solid materials in the form of insoluble carbonates, hydroxides, or other salts, a water softening unit, an absorption tower, a control device, a pump, a storage tank, or a power source, such as a generator, a battery, or a solar panel.

[0026] Details of one or more embodiments are set forth in the following description. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments. Accordingly, any of the various embodiments described herein may be combined to provide further embodiments. Aspects of the embodiments may be modified, as necessary, to employ concepts from the various patents, applications, and publications identified herein to provide further embodiments. Other features, objects, and advantages will become apparent from the specification, drawings, and claims.

[0027] The present disclosure may be understood by reference to the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram showing the structure and components of a custom HDCI cell (101-108) connected to a peristaltic pump (109) and a solution reservoir (110). [Figure 2]Figures 2A-2C are schematic diagrams illustrating the stabilization of metastable ζ-VO based on the topochemical deintercalation of Ag ions from β-AgVO. The crystal structures of (A) α-VO, (B) β-AgVO, and (C) ζ-VO products are shown. Figures 2D-2F illustrate the β, β', and C interstitial sites of ζ-VO arranged along 1D tunnels. [Figure 3] Figure 1 shows the refined X-ray diffraction (XRD) pattern of ζ-VO nanowires. Specifically, it shows the Rietveld refinement of the powder XRD pattern of ζ-VO prepared from the β-AgVO precursor. The XRD data are plotted on top of the refined pattern (32) (33). The residual values ​​are shown as 30 and the background is plotted as 31. The refined crystal structure is shown with partial residual Ag occupancy at the β-sites of the 1D tunnel. [Figure 4] Figure 1 shows scanning electron microscope (SEM) (A), transmission electron microscope (TEM) (B), and high-resolution, lattice-resolved TEM (C) images of ζ-V2O5 nanowires. [Figure 5A] Cycle data for potassium ion removal for CDI cells (A to C) and HDCI cells (E to G) are shown. [Figure 5B] Cycle data for potassium ion removal for a CDI cell (D) and an HDCI cell (H) are shown. [Figure 6A] Electrochemical cycling experiments comparing CDI (A to B) and HCDI (E to F) cells with a 15 mM NaCl aqueous solution flowing at 20 mL / min. The cells were cycled for different times, 15 min at 1.2 V for CDI (A and E) and 30 min for CDI (B and F), followed by potential reversal to -1.2 V. The cells were cycled a total of 40 times. Data were plotted as aqueous conductivity versus time. The average IRC of the cycles is inserted in each plot. [Figure 6B] Electrochemical cycling experiments comparing CDI (C to D) and HCDI (G to H) cells with 15 mM NaCl aqueous solution flowing at 20 mL / min. The cells were cycled for different periods of time, 1 hour at 1.2 V for CDI (C and G) and 2 hours for CDI (D and H), followed by potential reversal to -1.2 V. The cells were cycled a total of 40 times. Data were plotted as aqueous conductivity versus time. The average IRC of the cycles is inserted in each plot. [Figure 7A] Figure 1 shows electrochemical cycling results comparing CDI (A to B) and HCDI (E to F) cells with 15 mM aqueous LiCl solution flowing at a constant flow rate of 20 mL / min. The cells were cycled for different times: 15 min at 1.2 V for CDI (A and E) and 30 min for CDI (B and F), followed by potential reversal to -1.2 V. The cells were cycled a total of 40 times. Data were plotted as solution conductivity versus time. The average IRC of the cycles is inserted in each plot. [Figure 7B] Figure 1 shows electrochemical cycling results comparing CDI (C to D) and HCDI (G to H) cells with 15 mM LiCl aqueous solution flowing at a constant flow rate of 20 mL / min. The cells were cycled for different times: 1 hour at 1.2 V for CDI (C and G) and 2 hours for CDI (D and H), after which the potential was reversed to -1.2 V. The cells were cycled a total of 40 times. Data were plotted as solution conductivity versus time. The average IRC of the cycles is inserted in each plot. [Figure 8A]Figure 1 shows X-ray photometric (XPS) characterization of the ζ-VO composite desalination electrode, specifically: (A) high-resolution O 1s and V 2p3 / 2 XPS data for the uncycled ζ-VO cathode; (B) representative Cl 2p scan of the recovered ζ-VO electrode cycled at 1.2 V at a constant flow rate of 20 mL / min and then terminated at the ion uptake step; (C) O 1s and V 2p3 / 2 scans of a 15 mM KCl solution cycled through the HCDI ζ-VO cathode material at a potential of 1.2 V at a constant flow rate of 20 mL / min; and (D) high-resolution K 2p scan of a 15 mM KCl solution cycled through the HCDI ζ-VO cathode material at a potential of 1.2 V at a constant flow rate of 20 mL / min and then terminated at the ion uptake step. Peak identifications are inset in each panel along with the oxidation state of V identified. [Figure 8B] Figure 1 shows X-ray photospectroscopy (XPS) characterization of the ζ-V2O5 composite desalination electrode. Specifically, (E) O 1s and V 2p3 / 2 scans of a 15 mM NaCl aqueous solution cycled through the HCDIζ-VO5 cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by ion uptake. (F) Na 1s scan of a 15 mM NaCl aqueous solution cycled through the HCDIζ-VO5 cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by ion uptake. (G) O 1s and V 2p3 / 2 scans of a 15 mM LiCl aqueous solution cycled through the HCDIζ-VO5 cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by ion uptake. (H) Li 1s scan of a 15 mM LiCl aqueous solution cycled through the HCDIζ-VO5 cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by ion uptake. High-resolution XPS data for a 1 s scan are shown. Peak identifications are inset in each panel along with the identified V oxidation state. [Figure 9A]Figure 1 shows X-ray photospectroscopy (XPS) characterization of the ζ-VO composite desalination electrode. Specifically, (A) O 1s and V 2p3 / 2 scans of 5 mM KCl, 5 mM NaCl, and 5 mM LiCl cycled through the HCDI ζ-VO cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by quenching at the ion uptake step. (B) High-resolution XPS data of Na 1s scans of 5 mM KCl, 5 mM NaCl, and 5 mM LiCl cycled through the HCDI ζ-VO cathode material at a constant flow rate of 20 mL / min and a potential of 1.2 V, followed by quenching at the ion uptake step. Peak identifications are inset in each panel, along with the identified oxidation state of V. [Figure 9B] Figure 1 shows X-ray photospectroscopy (XPS) characterization of the ζ-VO composite desalination electrode. Specifically, (C) shows high-resolution XPS data for Li 1s scans of 5 mM KCl, 5 mM NaCl, and 5 mM LiCl cycled through the HCDI ζ-VO cathode material at a potential of 1.2 V at a constant flow rate of 20 mL / min and then terminated at the ion uptake step. Peak identifications are inset in each panel along with the identified oxidation state of V. [Figure 10] Powder XRD, specifically, X-ray diffraction data for an uncycled ζ-VO electrode, and evidence of filling of interstitial sites from electrodes cycled with a 15 mM KCl (1003), NaCl (1002), and LiCl (1001) deionized water solution and a 5 mM KCl, 5 mM NaCl, and 5 mM LiCl deionized water solution (1000). The label for each XRD pattern represents the stoichiometry measured by ICP-MS. [Figure 11A] (A) Graph showing desalination of mixed salt solutions with electrochemical cycling results of an HCDI cell flowing with an aqueous solution of 5 mM LiCl, 5 mM NaCl, and 5 mM KCl at a constant flow rate of 20 mL / min. The cell was cycled at 1.2 V for 2 hours, after which the potential was reversed to -1.2 V. The cell was cycled a total of 40 times. Data is plotted as solution conductivity versus time. [Figure 11B] (B) Desalination of a produced water stream in an HCDI cell cycling experiment is also demonstrated with a 10% by volume solution of FRW from a hydraulic fracturing operation in West Texas. The water was first filtered to remove residual oil and dissolved solids using a cement-based membrane, then allowed to flow at a constant flow rate of 20 mL / min. The cell was cycled at 1.2 V for 2 hours, after which the potential was reversed to -1.2 V. The cell was cycled a total of 40 times. The data is plotted as solution conductivity versus time. DETAILED DESCRIPTION OF THE INVENTION

[0029] Practical electrochemical desalination of FPW and brackish water streams requires the satisfaction of a number of important performance constraints. First, the process must provide a high ion rejection capacity (IRC), and the active material must remain insoluble even with small pH excursions. Second, the sequestration of ions from the flow stream must be totally reversible, so that the ions can be released in the form of a concentrated brine stream, allowing the cell to be continuously cycled. Third, the feasibility of the CDI process can be greatly enhanced if ion sequestration can be achieved with a degree of selectivity, such as to enable the selective capture of high-value ions. As described herein, these constraints can be met by using an HCDI cell with a ζ-VO positive electrode.

[0030] The disclosed HDCI cells (and devices including such cells) using ζ-VO as the cathode are useful for desalination of waters with salinities greater than 1000 ppm, such as seawater, brackish water, geothermal brines, synthetic brines, and flowback and / or produced waters.

[0031] FIG. 1 illustrates the structure of an HDCI cell (with components 101 through 108) connected to a peristaltic pump (109) and reservoir (110). Preferably, the exterior 101 comprises Delrin, a polyoxymethylene, high-performance acetal resin. In order of construction from top to bottom as depicted in FIG. 1, the next layers are a current collector (102), then a cathode (103) with a tunnel structure such as ζ-VO, then a cation exchange membrane (104), then a nylon separator (105), then a gasket (106), then an anion exchange membrane (107), then a carbon anode (108), then another current collector layer (102), and then the exterior 101. Preferably, the thickness of the ζ-VO positive electrode is between 2 nm and 1000 μm. This device can be used in the desalination methods described further herein.

[0032] ζ-VO has recently attracted considerable attention as a battery cathode material due to its high theoretical capacity (441 mAh / g), exceptional thermal and chemical stability, ability to accommodate Li and Mg ions through cation packing rearrangement without distortion during phase transition, low stress buildup during cation insertion, and excellent cyclability. The synthesis of metastable vanadium pentoxide cathode materials was previously described in U.S. Patent Publication No. 2020 / 0321614, which is incorporated herein by reference. The ζ-VO polymorph contains three crystallographically distinct vanadium centers, specifically, two distorted VO octahedra interwoven with VO square pyramids that define 1D tunnels oriented along the b-axis. In some embodiments, one or more of these vanadium centers may be substituted with molybdenum, tungsten, or niobium to alter the ion selectivity of the electrode material. Such substitution is carried out as a site-selective modification or doping, where molybdenum, tungsten, or niobium is heated with a vanadium precursor using standard solid-state chemistry methods.

[0033] Figures 2A to 2C show the reaction sequence used to stabilize ζ-V2O5. 0.33V2O5 nanowires were prepared by reacting silver acetate with α-V2O5 and topochemical deintercalation of Ag ions by treatment with HCl to give the ζ-V2O5 polymorph. ζ-V2O5 has multiple interstitial sites, β, β', and C, arranged along 1D tunnels, as shown in Figures 2D–F.

[0034] Figure 3 shows the refined XRD pattern of ζ-V2O5 nanowires, specifically, β-Ag 0.33 This shows a Rietveld refinement of the powder XRD pattern of ζ-V2O5 prepared from a V2O5 precursor. The XRD data are plotted on top of the refined pattern (32) (33). The residual values ​​are shown as 30 and the background is plotted as 31. The refined crystal structure is shown with partial residual Ag occupancy at the β sites of the 1D tunnels. The prepared nanowires crystallize in the monoclinic C2 / m space group with a β angle of 110.0°.

[0035] Figure 4 shows SEM (A) and TEM (B) images of the ζ-VO nanowires. The nanowires have roughly rectangular cross-sections with dimensions of 0.33 ± 0.09 μm and lengths ranging from 0.5 to 9 μm.

[0036] To demonstrate the potential of ζ-VO as a positive electrode for HCDI, a flow cell equipped with a ζ-VO positive electrode and an activated carbon negative electrode was compared with a conventional CDI cell with the same activated carbon negative and positive electrode pair. The electrodes were prepared to the same specifications and used in the same flow cell, differing only in the active electrode material. Aqueous solutions of 15 mM NaCl, KCl, and LiCl were used as the inlet stream. A constant potential was applied for different durations. Additionally, additional tests were performed on these test streams with (a) a 5 mM mixed salt solution of NaCl, KCl, and LiCl, and (b) a flow stream of actual FPW from the Permian Basin.

[0037] Figure 5 compares the cycling data for K ion removal at a constant potential of 1.2 V for CDI and HCDI cells with solution flow at a rate of 20 mL / min. The cells were cycled at 1.2 V for different times, ranging from 15 minutes to 2 hours, and then the potential was reversed to -1.2 V. The cells were cycled a total of 40 times. The CDI cells with activated carbon electrodes reached their maximum ion removal capacity more rapidly, peaking at a cycle time of 30 minutes, reflecting the limitations of ions that can be sequestered at the electrode surface. In contrast, the HCDI cells showed the characteristic signs of time-dependent ion removal (suggesting diffusion limitation from the propagation of intercalation waves), reaching an IRC of 6 mg / g, a 50% improvement compared to the CDI device after 2 hours. The cycle time can be between 10 seconds and 90 minutes, and the temperature at which the cycling occurs is preferably between 0°C and 95°C.

[0038] Figures 6 and 7 show the Na + Aqueous solution and Li + The IRCs of CDI and HCDI configurations (the latter with a ζ-VO positive electrode) using aqueous solutions were compared, and a 16% and 50% improvement, respectively, in the IRC for ζ-VO insertion compared to nonspecific capacitive removal was observed. In Figure 6, electrochemical cycling experiments were performed comparing CDI (A to D) and HCDI (E to H) cells with a 15 mM NaCl (sodium chloride) aqueous solution flowing at 20 mL / min. The cells were cycled at 1.2 V for different times, from 15 min to 2 h, and then the potential was reversed to -1.2 V. The cells were cycled a total of 40 times. The data were plotted as the aqueous conductivity versus time. The average IRC for the cycles is inset into each plot.

[0039] In Figure 7, electrochemical cycling results compare CDI (A to D) and HCDI (E to H) cells with 15 mM LiCl (lithium chloride) solution flowing at a constant flow rate of 20 mL / min. The cells were cycled at 1.2 V for different times, ranging from 15 minutes to 2 hours, and then the potential was reversed to -1.2 V. The cells were cycled a total of 40 times. The data were plotted as solution conductivity versus time. The average IRC for the cycles is inserted in each plot.

[0040] Table 1 summarizes the results for the three test solutions. Specifically, the IRC values ​​summarized in Table 1 contrast the performance of the CDI and HCDI devices with inlet streams of 15 mM KCl, NaCl, and LiCl solutions flowing at a rate of 20 mL / min. The half-cycle time is presented in the leftmost column for each sample. IRC values ​​are expressed in mg of salt removed per gram of electrode (left) and μmol of salt removed per gram of electrode (right). Values ​​are presented as averages over the cycles shown in Figure 5, along with the cycle-to-cycle error demonstrating variation.

[0041] [Table 1]

[0042] Several trends can be readily identified from Table 1. The kinetics of ion sequestration in CDIs using activated carbon electrodes was relatively fast for K ions, reaching saturation in 30 min, whereas Na and Li ions required approximately 1 h to saturate the activated carbon surface. This is consistent with the higher ionic conductivity of aqueous KCl solutions and is in keeping with the relatively small size of hydrated K ions. In contrast, a relatively slower uptake was observed for HCDIs with ζ-VO active electrodes, which is attributed to the need for solid-state diffusion through 1D tunnels after desolvation at the charged interface.

[0043] Although the potassium uptake in ζ-VO exceeds that of the CDI device at half-cycle times of 30 min, Li ion insertion into ζ-VO requires a half-cycle time of 2 h to exceed capacitive adsorption on activated carbon. This is due to the high potassium uptake in aqueous media (271 to 343 kJ / mol and 515 to 544 kJ / mol, respectively). + and Li + This is rationalized based on the difference in hydration free energy between the ionic radius and the K. A larger hydrated ionic radius and a larger hydration free energy pose a greater barrier to interfacial desolvation, resulting in a lower K at shorter cycle times. + This suggests a higher selectivity for K. However, the maximum IRCs on a molar basis after 2 h of HCDI were K (80 μmol / g), Na (62 μmol / g), and Li (71 μmol / g) (Table 1), suggesting a balance between the ionic and solvation radii of the ions and similar to the order of the intersite migration barriers and solid-state diffusion coefficients for the three ions. Although K has a smaller dehydration barrier and can desolvate and diffuse much faster within the tunnels of ζ-VO upon intercalation, fewer sites are available for potassium and sodium in mixed-stream or extended lithiation reactions, leaving greater potential for lithium intercalation.

[0044] Preferably, in the method of using an HDCI cell according to the present disclosure, the selective removal of lithium ions is at a concentration of 10 to 10% over other ions present in the aqueous solution. 6 Additionally, the method can include electrochemically cycling the HDCI cell under a first set of conditions to first selectively remove lithium ions, and electrochemically cycling the HDCI cell under a second set of conditions to enhance the selectivity of another ion, e.g., potassium or sodium, resulting in the removal of that ion.

[0045] ICP-MS (inductively coupled plasma mass spectroscopy) was performed on the recovered ζ-VO electrode after discharge, and the recovered material was washed three times with deionized water to remove surface-attached ions. Based on the ICP-MS measurements, a stoichiometry of 0.66 Li, 0.18 Na, and 0.07 K per VO formula unit was determined. This suggests the possibility of greater selectivity for Li-ion sequestration at longer cycle times. This again coincides with the order of the solid-state diffusion coefficients of the three ions in ζ-VO. Density functional theory (DFT) simulations showed that the barrier to Li-ion diffusion is 0.13 to 0.14 eV in ζ-VO, depending on the Li-ion stoichiometry, and the activation energy for Na-ion diffusion is substantially higher, from 0.47 to 0.95 eV.

[0046] X-ray photoelectron spectroscopy (XPS) data were obtained for electrodes recovered after the ion sequestration cycle and washed with deionized water to remove adsorbed ions (Figures 8 and 9). Li 1s, Na 1s, and K 2p peaks were observed at 56, 1070, and 292 eV, respectively, confirming the presence of intercalated ions. The as-prepared ζ-VO cathode material exhibited vanadium and oxygen manifolds centered at binding energies of 517 and 530 eV, respectively. Immediately after the lithiation reaction, a low-energy shoulder was observed corresponding to the V 2p peaks, which correspond to vanadium reduction. 3 / 2 The observed reduction of V to its tetravalent form is due to the β-M x This suggests the intercalation of ions to form V2O5, and supports the redox intercalation of ions within the 1D tunnels of ζ-V2O5. 3 / 2 The low-energy shoulder to the peak is β-Na x β-K with a lower degree of reduction of V2O5 x A similar observation is made in V2O5 materials.

[0047] Because XPS is surface sensitive, to obtain definitive evidence for ion intercalation (and not just surface adsorption), powder XRD measurements were performed on the ζ-VO electrode recovered after the ion sequestration cycle. Figure 10 compares the powder XRD pattern obtained for the sample after HCCI removal of Li, Na, and K ions with the XRD pattern of the as-prepared ζ-VO. Electrochemical cycling of the HDCI cell was performed on the electrode cycled in a solution of 15 mM KCl (1003), NaCl (1002), and LiCl (1001) in deionized water (1000) and a solution of 5 mM LiCl, 5 mM NaCl, and 5 mM LiCl in deionized water (1000). The labels on each XRD pattern in Figure 10 indicate the stoichiometry measured by ICP-MS.

[0048] Pawley refinement was performed on the powder XRD data, and the refined lattice parameters are listed in Table 2. The recovered sample remained crystallized in a monoclinic structure with a C2 / m space group. However, substantial volume expansions of 1.9%, 1.2%, and 0.4% were observed in the K + , Li + , and Na + The observed changes in lattice parameters and unit cell expansion are consistent with the ICP-MS-derived intercalation stoichiometry listed in Table 2. Similar lattice expansions have been observed for non-aqueous intercalation in ζ-VO single crystals, supporting the occupation of interstitial sites in the tunnels and the role of induced current response at the charged interface of the HCDI cell.

[0049] In particular, Li xBelow the threshold stoichiometry of x = 0.33 in VO, the inserted Li ions initially occupy pentacoordinated β-positions within the VO tunnels, slightly distorting the lattice (Figures 2D-F). However, as the Li occupancy increases, a cation rearrangement associated with tunnel expansion is observed, and the Li ions are positioned along more closely spaced tetracoordinated β'-positions (Figures 2D-F). This allows for a Li ion stoichiometry up to x = 0.67. However, Na and K ions are not accommodated within the β'-positions, but rather are accommodated at a stoichiometric maximum of 0.33 per formula unit. These ions are accommodated in the β-positions shown in Figures 2D-F.

[0050] Table 2 shows the ICP-MS results and unit cell parameters derived from Perweigh refinement for cathode materials cycled with mixed salt solutions containing 15 mM LiCl, 15 mM NaCl, 15 mM KCl, and 5 mM LiCl, 5 mM NaCl, and 5 mM KCl.

[0051] [Table 2]

[0052] Competitive sequestration from a mixed salt stream can be measured. Figure 11A shows the electrochemical performance of an HCDI cell with a ζ-VO positive electrode in removing cations from a mixed aqueous solution of LiCl, NaCl, and KCl at a flow rate of 20 mL / min, an applied potential of 1.2 V, and different half-cycle times. The ICP-MS results in Table 2 show a strong preference for Li-ion insertion after 2 h. Li ions account for 33% of the cations in solution but 68% of the intercalated ions (Table 2), indicating a means of selective sequestration. This is further supported by the XPS results in Figures 8 and 9. The high-resolution V 2p XPS spectra in Figures 8 and 9 and 6 show a distinct shoulder between 515 and 516 eV, indicating the presence of tetravalent vanadium, suggesting significant ion intercalation.

[0053] The powder XRD results in Figure 9 further demonstrate a 1.3% lattice expansion of ζ-VO upon ion intercalation from the mixed salt stream. This indicates that the kinetics of HCDI using the ζ-VO electrode are highly dependent on hydrated ion size and hydration energy, with lower hydration energy contributing to higher ionic conductivity and easier solvation at the intercalation electrode interface. However, when desolvation is no longer the limiting process, the IRC at extended times is proportional to the availability of interstitial sites and the migration barrier between bare ion sites. These results provide clear evidence for intercalative cation sequestration and suggest a means to generate ion selectivity.

[0054] In an attempt to demonstrate the feasibility of the ζ-VO cathode material for desalination and selective ion sequestration in an HCDI configuration, a FPW sample from a hydraulic fracturing operation in West Texas was filtered to remove residual oil and dissolved solids and then passed through the flow cell configuration depicted in Figure 1. The resulting aqueous solution had an extremely high salt content, which involved diluting the sample to 10% of its initial concentration before desalination. The salt content of the FPW was measured by ICP-MS (Table 3). A diluted sample cycled through the HCDI cell demonstrates effective removal of ionic impurities (Figure 10B). While evidence of sequestration in the porous ζ-VO electrode was observed for each of the ions identified in the initial solution, the ICP-MS results in Table 3 provide clear evidence for the selective sequestration of Li ions. These results provide clear evidence of the potential of ζ-VO as a cathode material for advantageous desalination and Li ion extraction from FPW.

[0055] Table 3 shows the ICP-MS results of the ionic composition of the residual salts upon evaporation of FPW. After first filtering the water to remove residual oil and dissolved solids using a cement-based membrane, the salts were recovered through evaporation of the aqueous phase. These results were compared with the ICP-MS results of the ionic content intercalated into the ζ-VO cathode after running the FPW stream as shown in Figure 5.

[0056] [Table 3]

[0057] As demonstrated, the ζ-V2O5 intercalation host with a tunnel structure acts as a favorable cathode material for desalination of aqueous salt solutions in the HCDI configuration. + , Na + , K. +Ion removal experiments were conducted with a mixed salt solution containing all three ions, an aqueous solution containing HCl, and a filtered FPW stream from the Permian Basin at different half-cycle times. The HCDI cell removed more Li from the water stream than a CDI cell assembled to the same specifications deployed within the same cell configuration. + Amount removed and K + Approximately 50% better removal rate, Na + The IRC of the ζ-VO5 cathode shows an approximately 16% improvement. ICP-MS and XPS data confirm ion sequestration within the active ζ-VO5 electrode, the latter pointing to the reduction of vanadium, suggesting the operation of an induced current process. Perweigh refinement of the powder XRD data clearly indicates that ion sequestration occurs through ion insertion into the interstitial sites of the 1D tunnels of the ζ-VO5. The kinetics of ion removal is highly dependent on the free energy of hydration, which determines the ease of desolvation at the electrode / electrolyte interface. At longer times, the IRC is primarily a function of the ionic radius of the bare ion and its solid-state diffusion coefficient. The ζ-VO5 cathode is able to absorb Li from the mixed flow stream. + This demonstrates substantial selectivity in removal and enrichment of Li ions from FPW. Therefore, HCDI with a ζ-V2O5 cathode is promising not only for purifying FPW but also for selectively extracting valuable minerals required for the energy transition.

[0058] HDCI cells using ζ-VO electrodes and devices comprising the HDCI cells disclosed herein can also be used remotely by mounting the device on a mobile vehicle, such as a truck, or on a trailer that can be moved by the vehicle. Examples of remotely mounted HDCI devices include: (i) connectors and / or tubing for connecting the device to one or more product water or other aqueous solution storage tanks; (ii) one or more membranes / filters for deoiling or sludge removal; (iii) a nanofiltration unit; (iv) an HDCI cell with ζ-VO as the cathode; (v) a water softening unit; (vi) equipment for atmospheric plasma treatment; and (vii) one or more absorption towers. Preferably, the components of the HDCI device are secured to the vehicle or trailer to prevent damage during transport. The HDCI device may also include a control unit, a power source (e.g., a generator, battery, or solar panel), a pump, and / or other devices necessary to circulate the aqueous solution through the device, such as by means described below.

[0059] In an exemplary method of using the HDCI device described above to desalinate product water and recover lithium at a remote location, the product water may enter the device through a conduit and flow through a de-oiling or de-sludge membrane to remove residual oil and dissolved solids. The resulting aqueous solution may flow through a nanofiltration unit in an HDCI cell using a ζ-VO cathode to separate the lithium-rich brine from the de-value water. The lithium-rich brine flows into an atmospheric plasma treatment device that uses the effluent to plasma treat the brine, enabling the recovery of battery-grade LiCO. After processing through the nanofiltration unit, some of the remaining aqueous solution may flow through a water softener and an absorber to recover both the de-value water and the copper- and cobalt-rich brine. [Example]

[0060] Example 1 Synthesis of ζ-V2O5 ζ-VO was synthesized using a previously reported method (see Marley, PM; Abtew, TA; Farley, KE; Horrocks, GA; Dennis, RV; Zhang, P.; Banerjee, S., Emptying and filling a tunnel bronze. Chemical Science 2015, 6 (3), pp. 1712-1718). Briefly, silver acetate (0.2811 g) (Alfa Aesar) and α-VO (0.9189 g) (EMD Millipore) were ball milled for 30 min in a SPEX SamplePrep 5100 Mixer Mill using methacrylate grinding beads. Next, 0.33 g of the resulting mixture was added to 16 mL of deionized water (NANOpure Diamond system, Barnstead International, ρ = 18.2 MΩ cm), placed in a polytetrafluoroethylene container, and inserted into a steel acid digestion vessel (Parr Instrument Company). The sealed hydrothermal vessel was heated at 210 °C for 72 hours. The vessel was allowed to cool to room temperature, and the resulting green precipitate (β-Ag 0.33 The β-Ag (VO) was filtered and washed with copious amounts of water and 2-propanol. The resulting β-Ag was placed in a polytetrafluoroethylene cup containing 15 mL of deionized water (ρ = 18.2 MΩ cm) and 0.8 mL of HCl (12 M) (Avantor). 0.33 VO (0.33 g) was added and the mixture was placed in a Parr Instrument Company steel acid digestion vessel. The hydrothermal vessel was heated at 210 °C for 24 hours. The vessel was cooled to room temperature, and the resulting brown precipitate (ζ-VO, AgCl) was filtered and washed with copious amounts of deionized water (ρ = 18.2 MΩ cm) and 2-propanol. The AgCl was then removed by treating the precipitate with 0.5 M NaSO, followed by washing with copious amounts of deionized water (ρ = 18.2 MΩ cm).

[0061] Example 2 Construction and testing of HDCI cells using ζ-V2O5 as the positive electrode A cathode material for HCDI cells was prepared by mixing 160 mg of the active material (ζ-VO), 30 mg of Super-C45 conductive carbon black, and 1 mL of 10% by weight PVDF in N-methyl-2-pyrrolidone (NMP). The resulting slurry was manually stirred for 30 minutes until a uniform, viscous slurry was formed. The slurry was then cast to a thickness of 0.25 mm onto 15 μm-thick battery-grade aluminum foil using a BYK casting knife. The cast electrode was dried in a muffle furnace at 70 °C for 24 hours.

[0062] 160 mg of active material (Strem Chemicals, surface area 1300 to 1400 m 2 Anode materials for HCDI cells and cathode materials for CDI cells were prepared by mixing activated carbon (at 1000 kJ / g), 30 mg of Super-C45 conductive carbon black, and 1 mL of 10% by weight PVDF in N-methyl-2-pyrrolidone (NMP). The resulting slurry was manually stirred for 30 minutes until a uniform, viscous slurry was formed. The slurry was then cast to a thickness of 0.25 mm onto 15 μm-thick battery-grade aluminum foil using a BYK casting knife. The cast electrodes were dried in a muffle furnace at 70 °C for 24 hours.

[0063] A custom HCDI cell was constructed using Delrin sheathing, as depicted in Figure 1. The HCDI cell interior included a current collector (15.24 cm × 5.08 cm conductive copper tape), a cathode material (1 cm × 4 cm) (preferably ζ-VO), a cation exchange membrane (1.5 cm × 4.5 cm Nafion 115), two layers of nylon separator material (78 μm × 100 μm pore size VWR), a custom Viton gasket (1 / 32-inch McMaster Carr), two layers of separator (78 μm × 100 μm pore size VWR), an anion exchange membrane (Fumasep FAA-3-PK-130), anode material, and a current collector (15.24 cm × 5.08 cm conductive copper tape). These components were then sandwiched between Delrin sheathing and connected to a peristaltic pump (Omega FPU 421). Then, deionized water containing 15 mM NaCl, LiCl, or KCl, or a combination of all three salts, was passed through the cell at a rate of 20 mL / min.

[0064] A FPW sample from West Texas was also tested. The sample was recovered from a Southern Midland well in the Permian Basin of West Texas. The sample was filtered using a cement-based membrane as described by Rivera-Gonzalez et al. and then diluted to 10% of its original concentration using deionized water (Barnstead International NANOpure Diamond system, ρ = 18.2 MΩ·cm). The HCDI cell was connected to a Gamry Interface 1010E potentiostat in repeated chronoamperometry mode. A voltage of 1.2 V was applied to the cell at 15 minutes, 30 minutes, 1 hour, and 2 hours, at which point the potential reversed to -1.2 V, for a total of 40 cycles. The change in conductivity was measured using a combination of an ET915 conductivity electrode and an EPU357 conductivity iosPod and plotted as a function of time.

[0065] A CDI cell was constructed as depicted in Figure 1 and used for control testing using Delrin sheathing. The CDI cell interior included a current collector (15.24 cm x 5.08 cm conductive copper tape), cathode material (1 cm x 4 cm), cation exchange membrane (1.5 cm x 4.5 cm Nafion 115), two layers of nylon separator material (78 μm x 100 μm pore size VWR), a custom Viton gasket (1 / 32-inch McMaster Carr), two layers of separator (78 μm x 100 μm pore size VWR), anion exchange membrane (Fumasep FAA-3-PK-130), anode material, and a current collector (15.24 cm x 5.08 cm conductive copper tape). These components were then sandwiched between Delrin sheathing and connected to a peristaltic pump (Omega FPU 421). Subsequently, deionized water containing 15 mM NaCl, LiCl, or KCl, or a combination of all three salts, was flowed through the cell at a rate of 20 mL / min. The CDI cell was connected to a Gamry Interface 1010E potentiostat in chronoamperometry mode. A voltage of 1.2 V was applied to the cell at 15 minutes, 30 minutes, 1 hour, and 2 hours, at which point the potential reversed to -1.2 V, for a total of 40 cycles. The change in conductivity was measured using an ET915 conductivity electrode in combination with an EPU357 conductivity iosPod and plotted as a function of time.

[0066] First, the ion removal capacity was calculated by plotting a calibration curve for each aqueous salt solution by recording the change in ionic conductivity as a function of salt concentration. The change in conductivity after the ion removal step was converted to a concentration using the calibration curve and averaged for each measurement. The first few cycles correspond to the conditioning step. Then, Equation 1 (where C0 and C i are the salt concentrations before and after cycling, respectively, V is the volume of the solution, and M tot is the mass of both electrodes including the active material and the carbon black and binder material), was used to calculate the ion removal capacity.

[0067]

number

[0068] Example 3 Characterization Powder X-ray diffraction (XRD) was performed on the cycled cathode samples using a Bruker AXS D8 Endeavor powder X-ray diffractometer equipped with a Lynxeye PSD XTE detector and a copper Kα source (λ = 1.5418 Å). Collected diffraction patterns were subjected to Purwee refinement.

[0069] XPS experiments were performed using Mg Kα X-rays (source energy 1253.6 eV) in an Omicron DAR 400 XPS / UPS instrument equipped with a 128-channel microchannel plate Argus detector and a CN10 electron flood source to neutralize the sample charge. The energy resolution of the instrument was approximately 0.8 eV. High-resolution fine spectra were collected using triple acquisition with a pass energy of 100 eV (in constant analyzer energy mode), an energy step size of 0.05 eV, and a dwell time of 200 ms. All high-resolution spectra were calibrated using the C 1s line of adventitious carbon at 284.5 eV. Spectral line fitting was performed using CasaXPS 2.3.16 software, applying the Marquardt-Levenberg optimization algorithm.

[0070] Inductively coupled plasma mass spectroscopy (ICP-MS) was performed on the cycled cathode samples to determine the Sc 45 V was measured using a PerkinElmer NExION300D instrument based on an internal standard. 51 , Li 7 , Na 23 , and K 39The electrode was then dried under nitrogen in a Schlenk line and digested with concentrated nitric acid at 100 °C in a sealed centrifuge tube in a water bath. The solution was then diluted with Milli-Q purified HO until the estimated ion concentrations were within the range of 1 to 100 ppb. The relative uncertainty of the measured metal ion concentrations is 5%.

[0071] (References) JPEG2025539344000006.jpg190146JPEG2025539344000007.jpg215146JPEG2025539344 000008.jpg216146JPEG2025539344000009.jpg212146JPEG2025539344000010.jpg91146 [Explanation of symbols]

[0072] 101 Delrin exterior 102 Current collector, current collector layer 103 Cathode with tunnel structure 104 Cation Exchange Membrane 105 Nylon separator 106 Gasket 107 Anion Exchange Membrane 108 Carbon anode 109 Peristaltic Pump 110 Reservoir

Claims

1. a.ζ-V 2 O 5 a positive electrode material comprising: b. current collector, c. cation exchange membrane, d. separator layer; e. anion exchange membrane, and f. Negative electrode material A hybrid capacitive deionization cell (HDCI) cell for desalination, comprising:

2. ζ-V 2 O 5 10. The HDCI cell of claim 1, wherein the cathode material comprising:

3. The HDCI cell of claim 1 further comprising a Delrin exterior.

4. a. Using an aqueous solution with a salt concentration of more than 1000 ppm, 2 O 5 electrochemically cycling an HCDI cell comprising a positive electrode; b. removing at least one of lithium ions, potassium ions, or sodium ions from the aqueous solution; A method comprising:

5. ζ-V 2 O 5 5. The method of claim 4, wherein the cathode material comprising:

6. Lithium ions are removed from aqueous solutions with a selectivity for lithium ion removal of 10 to 10 over other ions. 6 5. The method of claim 4, wherein the α-amino acid is in the range of 2 times higher.

7. After electrochemically cycling the HCDI cell for selective removal of lithium ions, electrochemically cycling the HCDI cell for selective removal of one or more other ions; removing those other ions; The method of claim 6, further comprising:

8. 5. The method of claim 4, wherein each of the electrochemical cycles lasts for a time period between 10 seconds and 90 minutes.

9. ζ-V 2 O 5 5. The method of claim 4, wherein the thickness of the positive electrode is between 2 nm and 1000 μm.

10. 5. The method of claim 4, wherein the temperature at which each step is performed is between 0°C and 95°C.

11. 5. The method of claim 4, wherein the aqueous solution comprises flowback, produced water, seawater, brackish water, geothermal brine, or synthetic brine.

12. the aqueous solution is one or more of flowback or produced water; 12. The method of claim 11, further comprising filtering the aqueous solution to remove residual oil and dissolved solids prior to electrochemically cycling.

13. a. A conduit that can be attached to an aqueous solution storage tank; b. one or more additional conduits through which an aqueous solution can flow; c. a deoiling or sludge removing membrane connected to at least one conduit; d. a nanofiltration unit connected to the at least one conduit and connected to the HDCI cell; and e. Vehicles or trailers containing (a) to (e).

1. A HDCI apparatus for desalination in a remote location, comprising: f. The HDCI cell is (i) ζ-V 2 O 5 (ii) a current collector; (iii) a cation exchange membrane; (iv) a separator layer; (v) an anion exchange membrane; and (vi) a negative electrode material.

14. 14. The HDCI apparatus of claim 13, further comprising a unit for precipitating solid material in the form of an insoluble carbonate, hydroxide, or other salt.

15. The HDCI device of claim 13 further comprising a water softening unit.

16. The HDCI apparatus of claim 13 further comprising an absorber tower.

17. The HDCI device of claim 13 further comprising a control device.

18. The HDCI device of claim 13 further comprising a pump.

19. The HDCI device of claim 13 further comprising a storage tank.

20. The HDCI device of claim 13 , further comprising a power source, the power source being a generator, a battery, or a solar panel.

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