Seawater desalination and water electrolysis apparatus using salinity gradient power generation

Abstract

The present invention provides a seawater desalination and water electrolysis apparatus using salinity gradient power generation technology, comprising a reverse electrodialysis stack and osmotic membranes disposed on both sides of the reverse electrodialysis stack, wherein the reverse electrodialysis stack includes: an anode electrode; a cathode electrode; a first cell which is disposed between the anode electrode and the cathode electrode and which includes a cation exchange membrane, an anion exchange membrane and a bipolar membrane; and a second cell which is disposed between the first cell and the cathode electrode and which includes a cation exchange membrane and an anion exchange membrane.

Description

Seawater desalination and water electrolysis device using salinity gradient power generation

[0001] The present invention relates to a salinity gradient power generation technology and apparatus capable of seawater desalination and green hydrogen production without energy consumption. Specifically, it relates to a seawater desalination and water electrolysis apparatus utilizing salinity gradient power generation technology that desalinates seawater by recirculating brine and fresh water without inputting an external energy source, simultaneously produces electrical energy, hydrogen, and oxygen, additionally produces base and acid solutions by recirculating the concentrated water produced by seawater desalination, and discharges the concentrated water with its concentration lowered to seawater levels.

[0002] Salinity gradient power generation is a system that generates electricity by recovering the energy from the concentration difference generated during the mixing of solutions with different concentrations (e.g., brine, fresh water) in the form of electrical energy.

[0003] In particular, in a RED (Reverse Electro Dialysis) stack, cations and anions move through the cation exchange membrane and anion exchange membrane, respectively, due to the difference in ion concentration between seawater and freshwater. At this time, a chemical potential difference (membrane potential) is generated between the cation exchange membrane and the anion exchange membrane, and electrical energy is generated by the phenomenon of electron movement through a redox reaction utilizing the potential difference generated by the cation exchange membrane and the anion exchange membrane at the electrodes (positive electrode (anode), negative electrode (cathode)) located at both ends where multiple cation exchange membranes and anion exchange membranes are arranged alternately.

[0004] As such, RED refers to a power generation method that directly converts chemical energy generated as ions dissolved in brine move through cation exchange membranes and anion exchange membranes into fresh water into electrical energy.

[0005] Here, in order to enable the RED-type salinity gradient power generation device to exhibit power generation performance applicable in actual field conditions, ranging from a small-scale laboratory level, a stack of existing unit cells is used.

[0006] On the other hand, seawater desalination utilizing the reverse osmosis phenomenon extracts fresh water by moving ions from a low concentration to a high concentration while supplying pressure higher than the osmotic pressure of seawater; therefore, the seawater concentration increases, and consequently, the cost of the pressure energy that must be supplied rises.

[0007] Accordingly, in seawater desalination using the reverse osmosis phenomenon, energy costs account for 40% to 50% of the total desalination costs, which is very high, and if concentrated water is discharged into the ocean, it can destroy the marine ecosystem.

[0008] The purpose of the present invention is to provide a seawater desalination and water electrolysis device utilizing salinity gradient power generation technology that desalinates seawater by recirculating brine and fresh water without inputting an external energy source, simultaneously produces electrical energy, hydrogen, and oxygen, additionally produces base and acid solutions by recirculating the concentrated water produced by seawater desalination, and discharges the concentrated water with its concentration lowered to seawater levels.

[0009] A seawater desalination and water electrolysis device using salinity gradient power generation technology according to a first embodiment of the present invention for achieving the above-mentioned purpose comprises: a reverse electrodialysis stack; and osmotic membranes disposed on both sides of the reverse electrodialysis stack, wherein the reverse electrodialysis stack comprises an anode electrode; a cathode electrode; a first cell disposed between the anode electrode and the cathode electrode and comprising a cation exchange membrane, an anion exchange membrane, and a bipolar membrane; and a second cell disposed between the first cell and the cathode electrode and comprising a cation exchange membrane and an anion exchange membrane.

[0010] A seawater desalination and water electrolysis device according to the first embodiment of the present invention supplies water between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell and the second cell, wherein H₂ that has moved through the water supplied via the cation exchange membrane and the anion exchange membrane, respectively + Wow OH - A fresh water generating unit that generates and discharges fresh water through a pH neutralization reaction and recirculates raw water; an acid solution circulation unit that circulates an acid solution between the oxidation electrode portion between the osmotic membrane and the first cell and between the bipolar membrane of the first cell and the cation exchange membrane of the second cell; a base solution circulation unit that circulates a base solution between the reduction electrode portion between the osmotic membrane and the second cell and between the anion exchange membrane of the first cell and the bipolar membrane; an end plate disposed on the outside of the osmotic membrane; and a seawater supply unit that supplies seawater between the osmotic membrane and the end plate; and further comprises two electrode portions (oxidation electrode and reduction electrode) in contact with the osmotic membrane.

[0011] The acid solution comprises at least one of the group consisting of aqueous solutions of H2SO4, HNO3, H3PO4, HVO3, H2CO3, and HBrO, in which case the reaction for the formation of O2(g) becomes dominant at the oxidation electrode. On the other hand, acid solutions containing Cl ions, such as HCl, LiCl, and NH4Cl, can be used to preferentially induce the reaction of Cl2(g) instead of the reaction for the formation of O2(g) at the oxidation electrode.

[0012] The basic solution comprises at least one of the group consisting of aqueous solutions of NaOH, KOH, and NH4OH.

[0013] The anode electrode and the cathode electrode comprise at least one of the group including precious metals platinum, ruthenium (Ru), iridium (Ir) and alloys thereof, or transition metals Ni, Fe, Co, Mo and alloys thereof.

[0014] The seawater desalination and hydrogen production salinity difference power generation device according to the second embodiment of the present invention further includes a carbon dioxide mineralization unit that generates carbonates using high-concentration concentrated water discharged between the osmotic membrane and the end plate by the seawater supply unit in the first embodiment of the present invention.

[0015] The carbonate is at least one of the group consisting of calcium carbonate, sodium carbonate, magnesium carbonate, and hydromagnesite (Mg5(CO3)4(OH)2·4H2O, composed of magnesium, carbonate, and hydroxide ions).

[0016] The seawater desalination and hydrogen production salinity difference power generation device according to the second embodiment of the present invention may further include a base solution supply unit that supplies a base solution to the carbon dioxide mineralization unit.

[0017] A seawater desalination and hydrogen production salinity gradient power generation device according to a third embodiment of the present invention comprises: a reverse electrodialysis stack; and osmotic membranes disposed on both sides of the reverse electrodialysis stack, wherein the reverse electrodialysis stack comprises an anode electrode; a cathode electrode; a first cell disposed between the anode electrode and the cathode electrode and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM); a second cell disposed between the first cell and the cathode electrode and comprising a cation exchange membrane (CEM) and an anion exchange membrane (AEM); and a third cell disposed between the anode electrode and the first cell and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell. and includes a fourth cell disposed between the first cell and the second cell and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell.

[0018] A seawater desalination and hydrogen production salinity gradient power generation device according to the third embodiment of the present invention supplies water between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell, the second cell, the third cell, and the fourth cell, and H₂ that has moved through the water supplied via the cation exchange membrane and the anion exchange membrane, respectively. + Wow OH - A fresh water, acid solution, and base solution generating unit that generates and discharges fresh water, acid solution, and base solution through a pH neutralization reaction; an acid solution circulation unit that circulates an acid solution through an oxidation electrode portion between the osmotic membrane and the third cell, between the bipolar membrane (BPM) of the third cell and the cation exchange membrane (CEM) of the first cell, and between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the fourth cell; a base solution circulation unit that circulates a base solution through a reduction electrode portion between the osmotic membrane and the second cell, between the anion exchange membrane (AEM) of the first cell and the bipolar membrane (BPM), and between the anion exchange membrane (AEM) of the fourth cell and the bipolar membrane (BPM); and an end plate disposed on the outer side of the osmotic membrane; It includes a seawater circulation unit that supplies seawater between the osmotic membrane and the end plate and supplies concentrated water between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell and between the cation exchange membrane of the second cell and the bipolar membrane (BPM) of the fourth cell; and an oxidation electrode and a reduction electrode in contact with the osmotic membrane.

[0019] The seawater desalination and hydrogen production salinity gradient power generation device according to the fourth embodiment of the present invention further includes a carbon dioxide mineralization unit that generates carbonates using high-concentration concentrated water discharged between the osmotic membrane and the end plate by the seawater supply unit in the third embodiment of the present invention.

[0020] The fresh water, acid solution, and base solution generating unit supplies the base solution discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell to the carbon dioxide mineralization unit.

[0021] The fresh water, acid solution, and base solution generating unit can discharge the generated fresh water, acid solution, and base solution through separate pipes.

[0022] The acid solution generated between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell in the fresh water, acid solution, and base solution generation unit is an aqueous hydrochloric acid solution.

[0023] A seawater desalination and water electrolysis device using salinity gradient power generation technology according to embodiments of the present invention can provide the following effects.

[0024] First, it is possible to implement desalination technology that does not require energy input.

[0025] According to an embodiment of the present invention, desalination can be carried out using energy produced internally by utilizing the principle of salinity gradient power generation without using external energy.

[0026] Second, it is possible to implement a technology that does not cause environmental pollution through concentrated water.

[0027] According to an embodiment of the present invention, new resources can be produced by additionally generating a basic solution, for example, an aqueous sodium hydroxide solution, and an acid solution, for example, an aqueous hydrochloric acid solution, from the concentrated water without discharging the concentrated water to the outside.

[0028] Third, salinity gradient power generation technology capable of recirculating supply water can be implemented.

[0029] According to an embodiment of the present invention, sustainable salinity gradient power generation is possible because the concentrations of the acid solution and the base solution are maintained at a constant level and recycled, eliminating the need to supply additional acid solution and base solution from the outside, and the supplied water can also be recycled.

[0030] Fourth, economic feasibility can be increased by mineralizing through salinity gradient power generation.

[0031] According to an embodiment of the present invention, a basic solution capable of ensuring economic feasibility in the process of generating carbonates by introducing carbon dioxide can be produced without additional costs, thereby enabling resource utilization that contributes to the prevention of global warming and the carbon economy through carbon dioxide fixation.

[0032] Fifth, salinity gradient power generation technology capable of producing green hydrogen and clean oxygen can be implemented.

[0033] According to an embodiment of the present invention, while performing desalination using the principle of salinity gradient power generation, hydrogen can be produced at the electrode, particularly the cathode (reduction electrode), and oxygen at the anode (oxidation electrode).

[0034] FIG. 1 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention.

[0035] FIG. 2 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention.

[0036] FIG. 3 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to a second embodiment of the present invention.

[0037] FIG. 4 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the second embodiment of the present invention.

[0038] FIG. 5 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the third embodiment of the present invention.

[0039] FIG. 6 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the third embodiment of the present invention.

[0040] FIG. 7 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the fourth embodiment of the present invention.

[0041] FIG. 8 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the fourth embodiment of the present invention.

[0042] Figure 9 is a graph showing experimental results regarding the OCV (open circuit voltage) and energy production of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0043] Figure 10 is a graph showing the experimental results of pH changes before and after supply of supplied water, acid solution, and base solution in a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0044] Figure 11 is a graph showing the experimental results of the change in conductivity before and after supplying water, acid solution, and base solution supplied to a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0045] FIG. 12 is a graph showing the experimental results of the change in the amount of water supplied before and after supply in a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0046] Figure 13 is a graph showing the experimental results of the change in the amount of hydrogen produced by a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0047] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. The meaning of "comprising" as used in the specification specifies a particular characteristic, area, integer, step, action, element, and / or component, and does not exclude the presence or addition of other particular characteristic, area, integer, step, action, element, component, and / or group.

[0048] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0049] Additionally, identical or corresponding components are assigned the same or similar reference numbers regardless of drawing symbols, and redundant descriptions thereof are omitted; furthermore, for the convenience of explanation, the size and shape of each illustrated component may be exaggerated or reduced.

[0050] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Accordingly, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid the present invention being interpreted ambiguously. Throughout the specification, like reference numerals refer to like components.

[0051] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0052] Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0053] Hereinafter, a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the present invention will be described in detail with reference to FIGS. 1 to 8.

[0054] FIG. 1 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the first embodiment of the present invention. FIG. 2 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the second embodiment of the present invention. FIG. 4 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the second embodiment of the present invention. FIG. 5 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the third embodiment of the present invention. FIG. 6 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the third embodiment of the present invention. FIG. 7 is a schematic diagram showing the configuration of a seawater desalination and water electrolysis device using salinity difference power generation technology according to the fourth embodiment of the present invention. FIG. 8 is a diagram showing the process flow of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the fourth embodiment of the present invention.

[0055] Referring to FIG. 1, a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention includes a reverse electrodialysis stack (100) and osmotic membranes (200) disposed on both sides of the reverse electrodialysis stack.

[0056] A reverse electrodialysis (RED) stack (100) comprises an anode electrode (110); a cathode electrode (120); a first cell (130) disposed between the anode electrode (110) and the cathode electrode (120) and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM); and a second cell (140) disposed between the first cell (130) and the cathode electrode (120) and comprising a cation exchange membrane (CEM) and an anion exchange membrane (AEM).

[0057] In addition, the seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention supplies water between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130) and the second cell (140), and H which has moved through the water supplied via the cation exchange membrane and the anion exchange membrane, respectively + Wow OH -A fresh water generating unit (300) that generates and discharges fresh water by a pH neutralization reaction; an oxidation electrode portion between the osmotic membrane (200) and the first cell (130), more specifically between the anode electrode (110) and the cation exchange membrane (CEM) of the first cell (130), and an acid solution circulation unit (400) that circulates an acid solution between the first cell (130) and the second cell (140), more specifically between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the second cell (140); It includes a base solution circulation unit (500) that circulates a base solution between the osmotic membrane (200) and the second cell (140), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the second cell (140), and between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130); an end plate (600) disposed on the outside of the osmotic membrane (200); and a seawater supply unit (700) that supplies seawater between the osmotic membrane (200) and the end plate (600).

[0058] The acid solution circulation unit (400) circulates the acid solution between the osmotic membrane (200) and the first cell (130), more specifically between the anode electrode (110) and the cation exchange membrane (CEM) of the first cell (130), and between the first cell (130) and the second cell (140), more specifically between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the second cell (140).

[0059] The acid solution comprises at least one of the group consisting of aqueous solutions of H2SO4, HNO3, H3PO4, HVO3, H2CO3, and HBrO.

[0060] Preferably, the acid solution is a diluted aqueous sulfuric acid (H2SO4) solution having a concentration of 0.1 M to 2 M.

[0061] In sulfuric acid solution, the generation of oxygen gas by OH- ions, which have a lower potential than the oxidation reaction of water, is SO4 2-It occurs more quickly and predominantly than S2O6 gas produced by the oxidation of ions.

[0062] Accordingly, the anode electrode (110) produces 2H2O(l) ==> 4H by the water decomposition of the sulfuric acid solution. + Since oxygen gas is generated by the reaction (aq) + O2(g) + 4e-, the H of the sulfuric acid solution transferred to the low-concentration water supplied between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130) in the fresh water generation unit (300) through the cation exchange membrane (CEM) + The deficiency of ions is compensated for by H in the oxidation reaction of the anode electrode. + It is replenished by generating ions. Accordingly, the generation of toxic gases in the sulfuric acid solution can be suppressed.

[0063] Meanwhile, a low-concentration aqueous solution of nitric acid (HNO3) can be used as the acid solution, but NO3 + Due to the low vapor pressure of the ions, they may naturally vaporize and generate toxic gases. Additionally, aqueous solutions of H3PO4, HVO3, H2CO3, and HBrO have lower electrical conductivity compared to sulfuric acid solutions, which may result in lower output.

[0064] In addition, since the hydrochloric acid solution has a higher potential than the oxidation reaction of water, chlorine (Cl2) gas is generated more rapidly than oxygen gas from the oxidation of water. Therefore, it is insufficient to automatically replenish the deficit of H+ that has moved from the supplied acid solution, the hydrochloric acid solution, to water through the cation exchange membrane (CEM), and can cause corrosion in the system due to toxic gases such as chlorine gas and Cl ions.

[0065] The base solution circulation unit (500) circulates the base solution between the osmotic membrane (200) and the second cell (140), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the second cell (140), and between the anion exchange membrane (AEM) of the first cell (130) and the bipolar membrane (BPM).

[0066] The basic solution comprises at least one of the group consisting of aqueous solutions of NaOH, KOH, and NH4OH.

[0067] Preferably, the base solution is a diluted aqueous sodium hydroxide (NaOH) solution having a concentration of 0.1 M to 2 M.

[0068] The anode electrode and the cathode electrode comprise at least one of the group including precious metals platinum, ruthenium (Ru), iridium (Ir) and alloys thereof, or transition metals Ni, Fe, Co, Mo and alloys thereof.

[0069] The seawater supply unit (700) supplies seawater between the osmotic membrane (200) and the end plate (600).

[0070] The osmotic membrane (200) allows water to pass from low-concentration seawater with low electrical conductivity to high-concentration acid solution and base solution due to the difference in concentration between the acid solution or base solution and the seawater, and this water becomes a raw material for electrochemical seawater desalination.

[0071] Hereinafter, with reference to FIGS. 1 and FIGS. 2, the process sequence of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention will be described.

[0072] <Description of process sequence according to the first embodiment of the present invention>

[0073] ① and ①'fairness

[0074] When water is supplied by the fresh water generation unit (300) between the cation exchange membrane and the anion exchange membrane of the first cell (130) and between the cation exchange membrane and the anion exchange membrane of the second cell (140), H that has passed through the cation exchange membranes (CEM) of the first cell (130) and the second cell (140) + Ions and OH that have passed through the anion exchange membrane (AEM) of the first cell (130) and the second cell (140) - Additional water (H2O) is generated by ions and discharged as fresh water in an amount greater than the supplied water.

[0075] Additionally, although not shown, some of the water released from the freshwater generation unit (300) can be supplied and circulated between the cation exchange membrane and the anion exchange membrane of the first cell (130) and between the cation exchange membrane and the anion exchange membrane of the second cell (140).

[0076] ① The fresh water generation process by the process of 'additionally generates a potential difference by neutralizing the pH of the reverse electrodialysis (RED) stack (100), thereby increasing the power generation efficiency of the reverse electrodialysis (RED) stack (100) and increasing the efficiency of hydrogen and oxygen generation by water electrolysis reaction at both electrode parts.

[0077] ② and ②'Fairness

[0078] A basic solution, for example, an aqueous solution of sodium hydroxide (NaOH), is supplied and circulated between the osmotic membrane (200) and the second cell (140), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the second cell (140), and between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130).

[0079] When water passing through the osmotic membrane (FO) (200) is supplied to the sodium hydroxide aqueous solution between the osmotic membrane (200) and the second cell (140), the water undergoes a reduction reaction of the cathode electrode (120) to produce OH - It is added to the sodium hydroxide solution, and additional hydrogen is produced.

[0080] 4Na + + 4H2O + 4e- → 4Na + + 4OH - + 4H + + 4e- → 4NaOH (solution) + 2H2 (gas)

[0081] 4OH additionally generated by the reduction reaction of the cathode electrode (120) - Some of the ions pass through the anion exchange membrane (AEM) of the second cell (140).

[0082] 4OH additionally generated by the reduction reaction of the cathode electrode (120) - High OH having some of the remaining ions - An aqueous sodium hydroxide solution having an ion concentration is discharged between the osmotic membrane (200) and the second cell (140) by a base solution circulation unit (500) and supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130).

[0083] High OH - OH of an aqueous sodium hydroxide solution having ion concentration - Some of the ions pass through the anion exchange membrane (AEM) of the first cell (130) and are discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130) and high OH - Na+ ions in an aqueous sodium hydroxide solution with a certain ion concentration cannot pass through a bipolar membrane (BPM).

[0084] OH by this process - The sodium hydroxide aqueous solution, having reached ion balance, is discharged between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130) by the base solution circulation unit (500) and supplied again between the osmotic membrane (200) and the second cell (140).

[0085] ③ and ③'Fairness

[0086] An acid solution, for example, an aqueous solution of sulfuric acid (H2SO4), is supplied and circulated between the osmotic membrane (200) and the first cell (130), more specifically between the anode electrode (110) and the reduction electrode portion between the cation exchange membrane (CEM) of the first cell (130), and between the bipolar membrane (BPM) of the first cell (130) and the second cell (140).

[0087] When water that has passed through the osmotic membrane (FO) (200) is supplied to the aqueous sulfuric acid (H2SO4) solution between the osmotic membrane (200) and the first cell (130), the water is H by the oxidation reaction of the anode electrode (110). + It is added to the yellow ray solution, and additional oxygen is generated.

[0088] 2H2O → O2(gas) + 4H + + 4e-(movement from anode electrode to cathode electrode)

[0089] 4H additionally generated by the oxidation reaction of the anode electrode (110) + Some of the ions pass through the cation exchange membrane (CEM) of the first cell (130) and additionally 4H is generated by the oxidation reaction of the anode electrode (110). + High H having some of the remaining ions + An aqueous solution of sulfuric acid (H2SO4) having an ion concentration is discharged between the osmotic membrane (200) and the first cell (130) by the acid solution circulation unit (400) and supplied between the first cell (130) and the second cell (140).

[0090] High H + H of an aqueous sulfuric acid (H2SO4) solution having an ion concentration + Some of the ions pass through the cation exchange membrane (CEM) of the second cell (140) and are discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell (140).

[0091] High H + SO4 of an aqueous sulfuric acid (H2SO4) solution having an ion concentration 2- The ions are not permeated by the bipolar membrane (BPM) of the first cell (130) and remain between the first cell (130) and the second cell (140).

[0092] H by this process + The aqueous sulfuric acid (H2SO4) solution that has reached ion balance is discharged between the first cell (130) and the second cell (140) by the acid solution circulation unit (400) and supplied again between the osmotic membrane (200) and the first cell (130).

[0093] ④ and ④' process

[0094] Seawater supplied between the osmotic membrane (200) and the end plate (600) by the seawater supply unit (700) moves to the anode electrode (110) and the cathode electrode (120) through the osmotic membrane (FO: Forward Osmosis) (200). Water molecules of seawater, which have a relatively lower concentration compared to seawater, move through the osmotic membrane (200) that causes osmosis and lower the concentration of the sulfuric acid solution and sodium hydroxide solution, which have a relatively high concentration.

[0095] Here, seawater may contain a neutral solution between 3.0 and 3.5 wt%.

[0096] The high concentration of seawater (concentrated water) that has lost water molecules moved through the osmotic membrane (200) is discharged between the osmotic membrane (200) and the end plate (600) by the seawater supply unit (700).

[0097] A seawater desalination and water electrolysis device using salinity gradient power generation technology according to the first embodiment of the present invention utilizes H from high-concentration acidic solutions and basic solutions, respectively. + , OH - Desalination can proceed by moving ions into fresh water to generate additional water, and the H of acid and basic solutions + , OH - Ions are repeatedly regenerated through water splitting reactions at the anode and cathode electrodes, circulating at the same concentration to enable concentration control.

[0098] In addition, the seawater desalination and water electrolysis device using the salinity difference power generation technology according to the first embodiment of the present invention can be recirculated by maintaining the concentrations of the acid solution, base solution, and feed water at a constant level without using additional energy.

[0099] Referring to FIGS. 3 and 4, the seawater desalination and water electrolysis device using salinity gradient power generation technology according to the second embodiment of the present invention further includes a carbon dioxide mineralization unit (800) in the configuration of the first embodiment.

[0100] In addition, the seawater desalination and water electrolysis device using salinity difference power generation technology according to the second embodiment of the present invention may further include a base solution supply unit (900) that supplies a base solution to a carbon dioxide mineralization unit (800).

[0101] The carbon dioxide mineralization unit (800) produces carbonates (e.g., calcium carbonate, sodium carbonate, magnesium carbonate, and hydromagnesite) from high-concentration seawater (concentrated water) discharged between the osmotic membrane (200) and the end plate (600) by the seawater supply unit (700).

[0102] The high concentration seawater (concentrated water) discharged between the osmotic membrane (200) and the end plate (600) is a family of Na + , Cl - , NO3 - Not only do ions exist, but also multivalent Mg 2+ , Ca 2+ , SO4 2- Includes the back.

[0103] Accordingly, according to the first embodiment of the present invention, monovalent Na in seawater + , Cl - , NO3 - Although energy can be easily produced by ions, the energy production efficiency may decrease by about 20% due to the movement of unremoved polyvalent ions. In addition, inorganic precipitates form at the cathode electrode, requiring periodic maintenance of seawater desalination and water electrolysis devices using salinity gradient power generation technology.

[0104] The carbon dioxide mineralization unit (800) supplies carbon dioxide to high-concentration seawater (concentrated water) to convert water molecules (H2O) in the seawater into H + Wow OH - Separate into, and carbon dioxide OH - Combined with HCO3 - Generate and H + It leaves behind ions, acidifying the seawater.

[0105] The base solution supply unit (900) supplies a base solution with a pH of > 10, for example, an aqueous sodium hydroxide solution, to the carbon dioxide mineralization unit (800).

[0106] Accordingly, the solubility of carbon dioxide in seawater is increased by a basic solution with a pH of > 10 in the carbon dioxide mineralization unit (800), and the multivalent Mg in seawater 2+ , Ca 2+ , SO4 2- Ions react with dissolved carbon dioxide to form carbonate minerals (e.g., calcium carbonate, sodium carbonate, magnesium carbonate, and hydromagnesite) which precipitate.

[0107] The carbon dioxide mineralization unit (800) collects the precipitated carbonate minerals and discharges seawater from which the polyvalent ions have been removed (④" process).

[0108] Accordingly, according to the second embodiment of the present invention, carbon dioxide is introduced to generate carbonates, thereby capturing carbon dioxide to prevent global warming, contributing to the carbon economy, and creating a new mineral called carbonate.

[0109] Referring to FIG. 5, a reverse electrodialysis stack of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to a third embodiment of the present invention comprises: an anode electrode (110); a cathode electrode (120); a first cell (130) disposed between the anode electrode (110) and the cathode electrode (120) and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM); and a second cell (140) disposed between the first cell (130) and the cathode electrode (120) and comprising a cation exchange membrane (CEM) and an anion exchange membrane (AEM). It includes a third cell (150) disposed between the anode electrode (110) and the first cell (130) and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell (130); and a fourth cell (160) disposed between the first cell (130) and the second cell (140) and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell (130).

[0110] In addition, a seawater desalination and water electrolysis device using salinity difference power generation technology according to the third embodiment of the present invention comprises a fresh water, acid solution, and base solution generating unit (300) that supplies water between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130), the second cell (140), the third cell (150), and the fourth cell (160) to generate and discharge fresh water, acid solution, and base solution; An acid solution circulation unit (400) for circulating an acid solution between the osmotic membrane (200) and the third cell (150), more specifically between the anode electrode (110) and the cation exchange membrane (CEM) of the third cell (150), between the third cell (150) and the first cell (130), more specifically between the bipolar membrane (BPM) of the third cell (150) and the cation exchange membrane (CEM) of the first cell (130), and between the first cell (130) and the fourth cell (160), more specifically between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the fourth cell (160); A base solution circulation unit (500) for circulating a base solution between the osmotic membrane (200) and the second cell (140), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the second cell (160), between the anion exchange membrane (AEM) of the first cell (140) and the bipolar membrane (BPM), and between the anion exchange membrane (AEM) of the fourth cell (160) and the bipolar membrane (BPM); an end plate (600) disposed on the outside of the osmotic membrane (200); A seawater circulation unit (700) that supplies seawater between the osmotic membrane (200) and the end plate (600) and supplies concentrated water between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) and between the cation exchange membrane of the second cell (140) and the bipolar membrane (BPM) of the fourth cell (160); and an oxidation electrode and a reduction electrode in contact with the osmotic membrane (200).

[0111] The acid solution circulation unit (400) circulates the acid solution between the osmotic membrane (200) and the third cell (150), more specifically between the anode electrode (110) and the cation exchange membrane (CEM) of the third cell (150), between the third cell (150) and the first cell (130), more specifically between the bipolar membrane (BPM) of the third cell (150) and the cation exchange membrane (CEM) of the first cell (130), and between the first cell (130) and the fourth cell (160), more specifically between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the fourth cell (160).

[0112] The acid solution comprises at least one of the group consisting of aqueous solutions of H2SO4, HNO3, H3PO4, HVO3, H2CO3, and HBrO.

[0113] Preferably, the acid solution is a diluted aqueous sulfuric acid (H2SO4) solution having a concentration of 0.1 M to 2 M.

[0114] In sulfuric acid solution, the generation of oxygen gas by OH- ions, which have a lower potential than the oxidation reaction of water, is SO4 2- It occurs more quickly and predominantly than S2O6 gas produced by the oxidation of ions.

[0115] The base solution circulation unit (500) circulates the base solution between the osmotic membrane (200) and the second cell (140), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the second cell (140), between the anion exchange membrane (AEM) of the first cell (140) and the bipolar membrane (BPM), and between the anion exchange membrane (AEM) of the fourth cell (160) and the bipolar membrane (BPM).

[0116] The basic solution comprises at least one of the group consisting of aqueous solutions of NaOH, KOH, and NH4OH.

[0117] Preferably, the base solution is a diluted aqueous sodium hydroxide (NaOH) solution having a concentration of 0.1 M to 2 M.

[0118] The anode (110) electrode and the cathode (120) electrode comprise at least one of the group including precious metals such as platinum, ruthenium (Ru), iridium (Ir) and alloys thereof, or transition metals such as Ni, Fe, Co, Mo and alloys thereof.

[0119] The seawater circulation unit (700) supplies seawater between the osmotic membrane (200) and the end plate (600).

[0120] The seawater circulation unit (700) supplies concentrated water, which is high-concentration seawater discharged between the osmotic membrane (200) and the end plate (600), to the anion exchange membrane (AEM) and bipolar membrane (BPM) of the third cell (150) and to the fourth cell (160) and the second cell (140).

[0121] The osmotic membrane (200) passes water from seawater at a low concentration to an acid solution and a base solution at a high concentration due to the difference in concentration between the acid solution or base solution and the seawater.

[0122] Hereinafter, with reference to FIGS. 5 and FIGS. 6, the process sequence of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to the third embodiment of the present invention will be described.

[0123] <Description of the process sequence of the third embodiment according to FIG. 6>

[0124] ①, ①', ①" and ①'" processes

[0125] When supplied between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130) and between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the fourth cell (160) by the fresh water, acid solution, and base solution generating unit (300), H that has passed through the cation exchange membrane (CEM) of the first cell (130) and the fourth cell (160) + Ions and OH that have passed through the anion exchange membrane (AEM) of the first cell (130) and the fourth cell (160) - Water (H2O) is additionally generated by ions and discharged as fresh water in an amount greater than the supplied water (processes ① and ①').

[0126] The fresh water generation process by the process of ①, ①' additionally generates a potential difference by neutralizing the pH of the reverse electrodialysis (RED) stack (100), thereby increasing the power generation efficiency of the reverse electrodialysis (RED) stack (100) and increasing the efficiency of hydrogen and oxygen generation by water electrolysis reaction at both electrode parts.

[0127] When supplied between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the third cell (150) by the fresh water, acid solution, and base solution generating unit (300), H that has passed through the cation exchange membrane (CEM) of the third cell (150) from the sulfuric acid solution + Cl that has passed through the anion exchange membrane (AEM) of the third cell (150) from ions and seawater - Hydrochloric acid (HCl) is produced by ions and released as a hydrochloric acid solution (①, ①" process).

[0128] Additionally, when supplied between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell (140) by the fresh water, acid solution, and base solution generating unit (300), Na from seawater that has passed through the cation exchange membrane (CEM) of the second cell (160) + OH that passed through the anion exchange membrane (AEM) of the second cell (140) in an aqueous solution of sodium hydroxide and ions - Sodium hydroxide (NaOH) is produced by ions and released as an aqueous sodium hydroxide solution (processes ① and ①"').

[0129] Here, fresh water, acid solution, and base solution are discharged through separate pipes and used according to their purpose without mixing.

[0130] ② and ②'Fairness

[0131] A basic solution, for example, an aqueous solution of sodium hydroxide (NaOH), is circulated between the osmotic membrane (200) and the fourth cell (160), more specifically between the cathode electrode (120) and the anion exchange membrane (AEM) of the fourth cell (160), between the second cell (140) and the fourth cell (160), more specifically between the anion exchange membrane (AEM) of the second cell (140) and the bipolar membrane (BPM) of the fourth cell (160), and between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130).

[0132] When water passing through the osmotic membrane (FO) (200) is supplied to the sodium hydroxide aqueous solution between the osmotic membrane (200) and the second cell (140), the water undergoes a reduction reaction of the cathode electrode (120) to produce OH - It is added to the sodium hydroxide solution, and additional hydrogen is produced.

[0133] 4Na + + 4H2O + 4e- → 4Na + + 4OH - + 4H + + 4e- → 4NaOH (solution) + 2H2 (gas)

[0134] 4OH additionally generated by the reduction reaction of the cathode electrode (120) - Some of the ions pass through the anion exchange membrane (AEM) of the second cell (140).

[0135] 4OH additionally generated by the reduction reaction of the cathode electrode (120) - High OH having some of the remaining ions - An aqueous sodium hydroxide solution having an ion concentration is discharged between the osmotic membrane (200) and the fourth cell (160) by a base solution circulation unit (500) and supplied between the anion exchange membrane (AEM) of the second cell (140) and the bipolar membrane (BPM) of the fourth cell (160), and between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130).

[0136] High OH -OH of an aqueous sodium hydroxide solution having ion concentration - Some of the ions pass through the anion exchange membrane (AEM) of the first cell (130) and are discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell (130), and pass through the anion exchange membrane (AEM) of the second cell (140) and are discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell (140).

[0137] Also, high OH - Na+ ions of the sodium hydroxide aqueous solution having an ion concentration cannot pass through the bipolar membrane (BPM) of the first cell (130) and the bipolar membrane (BPM) of the fourth cell (160).

[0138] OH by this process - The sodium hydroxide aqueous solution, having reached ion balance, is discharged between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the first cell (130) and between the second cell (140) and the fourth cell (160) by the base solution circulation unit (500) and supplied again between the osmotic membrane (200) and the fourth cell (160).

[0139] ③ and ③'Fairness

[0140] An acid solution, for example, an aqueous solution of sulfuric acid (H2SO4), is circulated between the osmotic membrane (200) and the third cell (150), more specifically between the anode electrode (110) and the cation exchange membrane (CEM) of the third cell (150), between the third cell (150) and the first cell (130), more specifically between the bipolar membrane (BPM) of the third cell (150) and the cation exchange membrane (CEM) of the first cell (130), and between the first cell (130) and the second cell (140), more specifically between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the second cell (140).

[0141] When water passing through the osmotic membrane (FO) (200) is supplied to the aqueous sulfuric acid (H2SO4) solution between the osmotic membrane (200) and the third cell (130), the water is H2SO4 by the oxidation reaction of the anode electrode (110).+ It is added to the yellow ray solution, and additional oxygen is generated.

[0142] 2H2O → O2(gas) + 4H + + 4e-(movement from anode electrode to cathode electrode)

[0143] 4H additionally generated by the oxidation reaction of the anode electrode (110) + Some of the ions pass through the cation exchange membrane (CEM) of the third cell (150) in the sulfuric acid solution and move between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the third cell (150).

[0144] 4H additionally generated by the oxidation reaction of the anode electrode (110) + High H having some of the remaining ions + An aqueous solution of sulfuric acid (H2SO4) having an ion concentration is discharged between the osmotic membrane (200) and the third cell (150) by the acid solution circulation unit (400) and supplied between the third cell (150) and the first cell (130) and between the first cell (130) and the fourth cell (160).

[0145] High H + SO4 of an aqueous sulfuric acid (H2SO4) solution having an ion concentration 2- The ions are not permeated by the bipolar membrane (BPM) of the first cell (130) and the third cell (150) and remain between the third cell (150) and the first cell (130) and between the first cell (130) and the fourth cell (160).

[0146] H by this process + The aqueous sulfuric acid (H2SO4) solution, having reached ion balance, is discharged between the third cell (150) and the first cell (130) and between the first cell (130) and the fourth cell (160) by the acid solution circulation unit (400) and supplied again between the osmotic membrane (200) and the third cell (150).

[0147] Processes ④ and ④' and ④"'

[0148] Seawater supplied between the osmotic membrane (200) and the end plate (600) by the seawater circulation unit (700) moves to the anode electrode (110) and the cathode electrode (120) through the osmotic membrane (FO: Forward Osmosis) (200). Water molecules of seawater, which have a relatively low concentration compared to acid and base solutions, move through the osmotic membrane (200) that causes osmosis and lower the concentration of the sulfuric acid solution and sodium hydroxide solution, which have a relatively high concentration.

[0149] Here, seawater may contain a neutral solution of 3.0 to 3.5 wt% or more.

[0150] The concentrated water, which has become high-concentration seawater after the water molecules moved through the osmotic membrane (200) are taken away, is discharged between the osmotic membrane (200) and the end plate (600) by the seawater supply unit (700).

[0151] The discharged high-concentration seawater (concentrated water) is supplied by the seawater circulation unit (700) between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) and between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140).

[0152] Cl, an anion of the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150). - , NO3 - and SO4 2- It passes through the anion exchange membrane (AEM) of the third cell (150). Na, which is a cation of the concentrate supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150). + , Ca 2+ , Mg 2+ It cannot pass through the bipolar membrane (BPM) of the third cell (150).

[0153] Accordingly, the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) contains anions (particularly, Cl - ) is deficient and cations (especially Na+ It is discharged in a state where there is a lot of ).

[0154] Cl, an anion of the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140). - , NO3 - and SO4 2- Na, which is a cation of the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140), cannot pass through the bipolar membrane (BPM) of the fourth cell (160). + , Ca 2+ , Mg 2+ It passes through the cation exchange membrane (CEM) of the second cell (140).

[0155] Accordingly, the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140) contains cations (particularly, Na + ) is deficient and anions (especially Cl - It is discharged in a state where there is a lot of ).

[0156] As a result, the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) and the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140) are discharged and mixed to maintain ion balance.

[0157] Referring to FIGS. 7 and 8, the seawater desalination and water electrolysis device using salinity gradient power generation technology according to the fourth embodiment of the present invention further includes a carbon dioxide mineralization unit (800) in the configuration of the third embodiment.

[0158] The carbon dioxide mineralization unit (800) produces carbonates (e.g., calcium carbonate, sodium carbonate, magnesium carbonate, and hydromagnesite) from high-concentration seawater (concentrated water) discharged between the osmotic membrane (200) and the end plate (600) by the seawater supply unit (700).

[0159] The process of the seawater desalination and water electrolysis device using salinity gradient power generation technology according to the 4th embodiment of the present invention is identical to processes ① to ③ of the process according to the 3rd embodiment of the present invention.

[0160] However, the process of the seawater desalination and water electrolysis device using salinity gradient power generation technology according to the 4th embodiment of the present invention will be described in detail with respect to the 4th process, which is different from the process according to the 3rd embodiment of the present invention.

[0161] The high concentration seawater (concentrated water) discharged between the osmotic membrane (200) and the end plate (600) is a family of Na + , Cl - , NO3 - Not only do ions exist, but also multivalent Mg 2+ , Ca 2+ , SO4 2- Includes the back.

[0162] Accordingly, according to the fourth embodiment of the present invention, monovalent Na in seawater + , Cl - , NO3 - Although energy can be easily produced by ions, the energy production efficiency may decrease by about 20% due to the movement of unremoved polyvalent ions. In addition, inorganic precipitates form at the cathode electrode, requiring periodic maintenance of the seawater desalination and water electrolysis equipment.

[0163] The carbon dioxide mineralization unit (800) supplies carbon dioxide to high-concentration seawater, thereby converting water molecules (H2O) in the seawater into H + Wow OH - Separate into, and carbon dioxide OH - Combined with HCO3 - Generate and H + It leaves behind ions, acidifying the seawater.

[0164] In addition, the fresh water, acid solution, and base solution generating unit (300) by process ① supplies the base solution, for example, an aqueous sodium hydroxide solution, discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell (140) to the carbon dioxide mineralization unit (800).

[0165] Accordingly, the solubility of carbon dioxide in seawater is increased by a basic solution with a pH of > 10 in the carbon dioxide mineralization unit (800), and the multivalent Mg in seawater 2+ , Ca 2+ , SO4 2- Ions react with dissolved carbon dioxide to form carbonate minerals (e.g., calcium carbonate, sodium carbonate, and magnesium carbonate), which then precipitate.

[0166] The carbon dioxide mineralization unit (800) collects the precipitated carbonate minerals and discharges seawater from which polyvalent ions have been removed.

[0167] The discharged seawater (concentrated water) is supplied by the seawater supply unit (700) between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) and between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140).

[0168] Cl, an anion of the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150). - It passes through the anion exchange membrane (AEM) of the third cell (150). Na, which is a cation of the concentrate supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150). + It cannot pass through the bipolar membrane (BPM) of the third cell (150).

[0169] Accordingly, the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) contains anions (particularly, Cl - ) is deficient and cations (especially Na + It is discharged in a state where there is a lot of ).

[0170] Cl, an anion of the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140). - Na, which is a cation of the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140), cannot pass through the bipolar membrane (BPM) of the fourth cell (160). + It passes through the cation exchange membrane (CEM) of the second cell (140).

[0171] Accordingly, the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140) contains cations (particularly, Na + ) is deficient and anions (especially Cl - It is discharged in a state where there is a lot of ).

[0172] As a result, the concentrated water supplied between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the third cell (150) and the concentrated water supplied between the bipolar membrane (BPM) of the fourth cell (160) and the cation exchange membrane (CEM) of the second cell (140) are discharged and mixed to maintain ion balance.

[0173] According to the fourth embodiment of the present invention, the concentrations of the acid solution and the base solution are maintained at a constant level and are recirculated, so there is no need to add additional base solution from the outside.

[0174] In addition, by injecting carbon dioxide to generate carbonates and capturing the carbon dioxide, it is possible to prevent global warming, contribute to the carbon economy, and create a new mineral called carbonate.

[0175] Hereinafter, experimental results according to an embodiment of the present invention will be described.

[0176] FIG. 9 is a graph showing experimental results regarding the Open Circuit Voltage (OCV) and energy production of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention. FIG. 10 is a graph showing experimental results regarding the change in pH before and after the supply of supplied water, acid solution, and base solution of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention. FIG. 11 is a graph showing experimental results regarding the change in conductivity before and after the supply of supplied water, acid solution, and base solution of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention. FIG. 12 is a graph showing experimental results regarding the change in the amount of supplied water before and after the supply of a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention. FIG. 13 is a graph showing experimental results regarding the change in the amount of hydrogen produced by a seawater desalination and water electrolysis device using salinity gradient power generation technology according to an embodiment of the present invention.

[0177] Four types of membranes were used in the experiment: cation exchange membranes, anion exchange membranes, bipolar membranes, and osmotic membranes (FO). The cation exchange membranes and anion exchange membranes used were developed by the Korea Institute of Energy Research and Technology, with a thickness of approximately 20 μm. The bipolar membrane used was a membrane from Company W, with a thickness of approximately 200 μm. The osmotic membrane used was from Company T, with a thickness of 100 μm. There are 12 stacked cells.

[0178] Based on the third embodiment of the present invention, one cell was used for the third cell and one for the second cell, and five cells were each used for the first cell and the fourth cell, for a total of 10 cells. One osmotic membrane (FO) was installed on each of the two electrode sections. The ion permeability of the ion exchange membrane and the effective surface area of ​​the osmotic membrane is 19.625 cm². 2 am.

[0179] The feed water used was water, dilute sulfuric acid, dilute sodium hydroxide, and seawater. Water with a conductivity of approximately 0.017 mS / cm was used, and 0.5 M aqueous solutions of dilute sulfuric acid and dilute sodium hydroxide were used. Additionally, a 3.0 M NaCl aqueous solution was used for the seawater. The feed water flow rate was 5 cc / min per cell.

[0180] The end plate was made of acrylic material, and a total of 6 Euro stacks were used for the supply water flow path, including the electrode part.

[0181] IrO2 was used as the oxidation electrode and Pt as the reduction electrode, and Ti was used as the electrode support to prevent corrosion. Supply water was introduced to the electrode section at a flow rate of approximately 10 cc / min.

[0182] In the graph of Figure 9, OCV refers to the potential difference generated in the ion exchange membrane due to the concentration difference or pH difference between the feed water when the circuit is not connected.

[0183] Referring to Fig. 9, monitoring the OCV across the entire stack for one hour resulted in an average potential difference of approximately 4.9 V. This translates to about 0.4 V per cell, which is approximately four times higher than that of a typical salinity gradient power generation stack based on seawater-freshwater standards. Under these conditions, the gross power density of the stack was measured to be a maximum of approximately 4.2 W / m². 2 It was found that... These results confirm that, as described in the description of the present embodiment, the stack according to the embodiment of the present invention can generate additional energy during the neutralization process due to the pH difference in addition to the salinity difference.

[0184] The graph in Figure 10 shows the results of monitoring pH changes over time during the process in which the supplied water is recirculated and flows back into the supply tank.

[0185] Referring to Figure 10, for water, almost no change in pH was observed, starting from an initial value of 7.32 and reaching a pH of approximately 7.18 after one hour. For sodium hydroxide, the initial pH was 13.132, and after one hour, it showed a value of approximately 13.033. Although the concentration of the sodium hydroxide aqueous solution appears to have been slightly diluted during the reaction process, the change in value was found to be minor, less than 1%. For sulfuric acid, the value increased slightly from an initial value of 0.01 to 0.13. Likewise, it was confirmed that the change was minor.

[0186] The graph in Fig. 11 shows the results of measuring the change in conductivity of the supply water under the same conditions as in Fig. 10. Referring to Fig. 11, the initial conductivity of water was 0.017 mS / cm, and the aqueous solutions of sodium hydroxide and sulfur dioxide were 108.93 mS / cm and 203.5 mS / cm, respectively. Even after 1 hour, no change in conductivity over a large range was observed, similar to the change in pH.

[0187] Referring to Fig. 12, when the concentration difference between the acid solution and fresh water and between the basic solution and fresh water is approximately 0.5 M, it is approximately 2.2 mL / m² 2 It was confirmed that the discharge was -1h. It showed a relatively uniform production rate depending on the difference in concentration.

[0188] Referring to Fig. 13, when the concentration difference between the acid solution and fresh water and between the basic solution and fresh water is approximately 0.5 M, it is approximately 0.0025 Nm 3 / m 2 It was confirmed that production occurred at a value of -1h. As the difference in concentration increased, the hydrogen production rate showed a tendency to gradually increase. This is presumed to be the result of an increase in the conductivity of the electrolyte required for the electrochemical reaction.

[0189] A person skilled in the art to which this specification pertains will understand that this specification may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of this specification is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included within the scope of this specification.

[0190] Meanwhile, the present specification and drawings disclose preferred embodiments of the present specification. Although specific terms have been used, they are used only in a general sense to facilitate the explanation of the technical content of the present specification and to aid in understanding the invention, and are not intended to limit the scope of the present specification. It is obvious to those skilled in the art that, in addition to the embodiments disclosed herein, other variations based on the technical concept of the present specification are possible.

Claims

1. A reverse electrodialysis stack; and osmotic membranes disposed on both sides of the reverse electrodialysis stack, comprising The above reverse electrodialysis stack comprises an anode electrode; a cathode electrode; a first cell disposed between the anode electrode and the cathode electrode and comprising a cation exchange membrane, an anion exchange membrane, and a bipolar membrane; and a second cell disposed between the first cell and the cathode electrode and comprising a cation exchange membrane and an anion exchange membrane, a seawater desalination and water electrolysis device using salinity gradient power generation technology.

2. In Paragraph 1, A freshwater generating unit that supplies water between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell and the second cell to generate and discharge additional freshwater and recirculate raw water; An acid solution circulation unit that circulates an acid solution between the above osmotic membrane and the above first cell, and between the bipolar membrane of the first cell and the cation exchange membrane of the second cell; A base solution circulation unit that circulates a base solution between the osmotic membrane and the second cell, and between the anion exchange membrane and the bipolar membrane of the first cell; An end plate disposed on the outer side of the above osmotic membrane; and A seawater desalination and water electrolysis device using salinity gradient power generation technology, further comprising a seawater supply unit that supplies seawater between the above-mentioned osmotic membrane and the above-mentioned end plate.

3. In Paragraph 2 A seawater desalination and water electrolysis device utilizing salinity gradient power generation technology, wherein the acid solution comprises at least one from the group consisting of aqueous solutions of H2SO4, HNO3, H3PO4, HVO3, H2CO3, and HBrO when the generation of O2(g) is dominant, and at least one from the group consisting of aqueous solutions of HCl, LiCl, and NH4Cl when the generation of Cl2(g) is dominant.

4. In Paragraph 2, A seawater desalination and water electrolysis device utilizing salinity gradient power generation technology, wherein the above-mentioned base solution comprises at least one of the group consisting of aqueous solutions of NaOH, KOH, and NH4OH.

5. In Paragraph 2, A seawater desalination and water electrolysis device using salinity gradient power generation technology, further comprising a carbon dioxide mineralization unit that generates carbonates in high-concentration concentrated water discharged between the osmotic membrane and the end plate by the seawater supply unit.

6. A reverse electrodialysis stack; and osmotic membranes disposed on both sides of the reverse electrodialysis stack, comprising The above reverse electrodialysis stack comprises an anode electrode; a cathode electrode; a first cell disposed between the anode electrode and the cathode electrode and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM); a second cell disposed between the first cell and the cathode electrode and comprising a cation exchange membrane (CEM) and an anion exchange membrane (AEM); a third cell disposed between the anode electrode and the first cell and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell; and a fourth cell disposed between the first cell and the second cell and comprising a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a bipolar membrane (BPM) in the same manner as the first cell, a seawater desalination and water electrolysis device using salinity gradient generation technology.

7. In Paragraph 6, Water is supplied between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the first cell, the second cell, the third cell, and the fourth cell, and H₂ that have moved through the water supplied via the cation exchange membrane and the anion exchange membrane, respectively. + Wow OH - A fresh water, acid solution, and base solution generating unit that generates and discharges fresh water, acid solution, and base solution through a pH neutralization reaction; An acid solution circulation unit that circulates an acid solution between the osmotic membrane and the third cell, between the bipolar membrane (BPM) of the third cell and the cation exchange membrane (CEM) of the first cell, and between the bipolar membrane (BPM) of the first cell and the cation exchange membrane (CEM) of the fourth cell; A base solution circulation unit that circulates a base solution between the above osmotic membrane and the above second cell, between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the above first cell (140), and between the anion exchange membrane (AEM) and the bipolar membrane (BPM) of the above fourth cell; An end plate disposed on the outer side of the above osmotic membrane; A seawater circulation unit that supplies seawater between the osmotic membrane and the end plate, and supplies concentrated water between the anion exchange membrane and the bipolar membrane (BPM) of the third cell, and between the cation exchange membrane and the bipolar membrane (BPM) of the second cell; and A seawater desalination and water electrolysis device utilizing salinity gradient power generation technology, further comprising an oxidation electrode and a reduction electrode in contact with the above-mentioned osmotic membrane.

8. In Paragraph 7, A seawater desalination and water electrolysis device using salinity gradient power generation technology, wherein cations and anions contained in the concentrated water supplied between the anion exchange membrane and the bipolar membrane (BPM) of the third cell and between the cation exchange membrane and the bipolar membrane (BPM) of the second cell are converted into acid and base solutions, respectively, diluted, and discharged at a final seawater concentration level.

9. In Paragraph 7, A seawater desalination and water electrolysis device using salinity gradient power generation technology, further comprising a carbon dioxide mineralization unit that generates carbonates using high-concentration concentrated water discharged between the osmotic membrane and the end plate by the seawater circulation unit.

10. In Paragraph 9, The above-mentioned fresh water, acid solution, and base solution generating unit supplies the base solution discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the second cell to the carbon dioxide mineralization unit, a seawater desalination and water electrolysis device utilizing salinity gradient power generation technology.

11. In Paragraph 10, The above-mentioned base solution is a sodium hydroxide aqueous solution, a seawater desalination and water electrolysis device utilizing salinity gradient power generation technology.

12. In Paragraph 8, The above-mentioned fresh water, acid solution, and base solution generating unit is a seawater desalination and water electrolysis device using salinity gradient power generation technology in which the acid solution discharged between the cation exchange membrane (CEM) and the anion exchange membrane (AEM) of the third cell is an aqueous hydrochloric acid solution.

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