Water treatment method and electrolysis device

Abstract

The present invention discloses a water treatment method and an electrolysis device, and relates to the technical field of water treatment. The water treatment method comprises: setting an electrolytic cell, wherein the electrolytic cell has an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane, wherein the anode of the anode liquid tank chamber and the cathode of the cathode liquid tank chamber are respectively connected to the positive and negative electrodes of the power supply of the electrolysis device; and wherein the anode liquid obtained by pretreatment of raw water and the configured cathode liquid are respectively introduced into the anode liquid tank chamber and the cathode liquid tank chamber, wherein the anode liquid is mainly composed of A X BO4 solution, the cathode liquid is AOH solution; as the electrolytic cell operates, A is produced in the anode liquid tank chamber. y HBO4 crystals produce hydrogen gas and AOH solution with increased concentration in the cathode liquid tank chamber; wherein A represents a monovalent metal, B represents an S element or a P element, x=2 or 3, y=1 or 2, H represents a hydrogen element, O represents an oxygen element, and OH represents a hydroxide ion.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a water treatment method and an electrolysis device. Background Art

[0002] In the chemical industry, sodium sulfate (Na2SO4) is a common by-product of some chemical processes. For example: 1) Papermaking industry: In the pulp manufacturing process, especially in the sulfate process, a large amount of sodium sulfate is generated. This method uses a mixture of sodium sulfate and sodium carbonate as a cooking liquid. 2) Dye and pigment production: Sodium sulfate can appear as a by-product in some dye and pigment production processes, especially those involving sulfuric acid. 3) Pharmaceutical industry: Sodium sulfate may also be produced as a by-product in some drug synthesis processes, especially those involving sulfate intermediates. In these processes, sodium sulfate by-products usually exist in the form of sodium sulfate solution. If sodium sulfate is to be recovered, it needs to be treated by crystallization, drying, etc. In addition, sodium sulfate by-products often contain other impurities, which further increases the difficulty and cost of recovery. In addition, there is an adequate supply of sodium sulfate on the market, and the selling price of sodium sulfate is not high. These factors lead to the problem of inconvenient handling of sodium sulfate by-products.

[0003] In addition, with the transformation of the energy industry, the demand for lithium-ion secondary batteries continues to rise, and the output of lithium mines mainly based on spodumene is increasingly difficult to meet the demand. Therefore, the extraction of lithium from lithium-containing liquid minerals such as salt lake brine, underground brine, oil and gas field water and geothermal water, and lithium-containing wastewater from the waste lithium battery recycling industry has gradually received attention. In addition to lithium, lithium-containing liquid minerals such as salt lake brine and underground brine often contain metal impurities such as sodium, calcium, and magnesium, among which sodium exists in the form of monovalent metal ions, and the rest are mainly divalent or higher metal ions. Divalent or higher metal ions such as calcium and magnesium are mainly extracted from the mother liquor through the impurity removal process; lithium is extracted from lithium-containing liquid minerals in the form of lithium salts through the lithium extraction process; sodium is extracted from lithium-containing liquid minerals in the form of sodium salts through the salt precipitation process after the impurity removal process and the lithium extraction process (currently mainly using the evaporation crystallization method). Sodium salt can be sodium sulfate, so it also faces the aforementioned problem of inconvenience in handling.

[0004] On the other hand, a large amount of wastewater is generated in people's daily life and industrial production (the aforementioned sodium sulfate byproduct is usually present in industrial wastewater in the form of sodium sulfate solution). Most of these wastewaters contain pollutants exceeding the standard and cannot be discharged directly. They need to be treated. From another perspective, with the development of the hydrogen energy industry, the demand for hydrogen in society is gradually increasing. If the above wastewater can be used to produce hydrogen, it is expected to turn the burden into power. At present, the electrolysis of water hydrogen production equipment mainly includes alkaline electrolyzers, AEM (anion exchange membrane) electrolyzers and PEM (proton exchange membrane) electrolyzers, and CEM (cation exchange membrane) electrolyzers are relatively rare. CEM (Cation Exchange Membrane) is a special type of ion exchange membrane, which is characterized by the ability to selectively allow cations to pass through and block anions from passing through. It is mainly used in electrodialysis, fuel cells, flow batteries, ion exchange and other fields. Summary of the invention

[0005] Based on the above background, it is proposed to develop a water treatment method and an electrolysis device based on a CEM electrolyzer, which can provide a novel idea for treating sodium sulfate and other similar substances. It not only solves the problem of inconvenient treatment, but also can obtain a variety of by-products including hydrogen.

[0006] In a first aspect, a water treatment method is provided, comprising: providing an electrolytic cell, the electrolytic cell having an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane, the anode of the anode liquid tank chamber and the cathode of the cathode liquid tank chamber being respectively connected to the positive and negative electrodes of the power supply of the electrolysis device; introducing the anode liquid obtained by pre-treatment of raw water and the prepared cathode liquid into the anode liquid tank chamber and the cathode liquid tank chamber respectively, the anode liquid mainly consisting of A X BO4 solution, the cathode liquid is AOH solution; as the electrolytic cell operates, A is produced in the anode liquid tank chamber. y HBO4 crystals produce hydrogen gas and AOH solution with increased concentration in the cathode liquid tank chamber; wherein A represents a monovalent metal, B represents an S element or a P element, x=2 or 3, y=1 or 2, H represents a hydrogen element, O represents an oxygen element, and OH represents a hydroxide ion.

[0007] In a second aspect, an electrolysis device is provided, comprising an electrolytic cell, wherein the electrolytic cell has an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane, wherein the anode of the anode liquid tank chamber and the cathode of the cathode liquid tank chamber are respectively connected to the positive and negative electrodes of the power supply of the electrolysis device; the anode liquid used in the anode liquid tank chamber is mainly composed of A X BO4 solution, the cathode liquid used in the cathode liquid tank chamber is AOH solution; as the electrolytic cell operates, A is produced in the anode liquid tank chamber. yHBO4 crystals, and hydrogen gas and AOH solution with increased concentration are produced in the cathode liquid tank chamber; wherein A represents a monovalent metal, B represents an S element or a P element, x=2 or 3, y=1 or 2, H represents a hydrogen element, O represents an oxygen element, and OH represents a hydroxide ion.

[0008] The above-mentioned water treatment method and electrolysis device provide a novel idea for treating sodium sulfate and similar substances (such as lithium sulfate, sodium phosphate, lithium phosphate). Take the treatment of sodium sulfate as an example: by using an electrolytic cell with a specific structure, sodium sulfate (NaHSO4) crystals can be precipitated in the anode chamber to achieve the separation and recycling of sodium salts in raw water or anode liquid; the cathode chamber can produce hydrogen and concentrated sodium hydroxide solution during the electrolysis process. Hydrogen can be used as a clean energy source, and concentrated sodium hydroxide solution can also be used as a chemical raw material. The above-mentioned electrolytic cell uses CEM membrane as a diaphragm, which can effectively separate the anode and cathode products to prevent them from mixing with each other and affecting the product purity. The CEM membrane only allows the cationic Na + By blocking anions, the independent reaction of the cathode and anode is ensured. Compared with the traditional salt precipitation process, the separation process of sodium sulfate in this method is changed from evaporation crystallization to electrolytic precipitation, which can reduce energy consumption, and the operating temperature of the electrolysis process is low, the equipment corrosion is small, and it is easy to realize automatic control. By connecting the electrolytic cells in series or in parallel, the process can be enlarged and continuous production can be achieved, which has good industrial application prospects.

[0009] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings constituting a part of this specification are used to assist the understanding of the present invention. The contents provided in the drawings and the related descriptions in this specification can be used to explain the present invention, but do not constitute improper limitations on the present invention.

[0011] Figure 1 The figure is a schematic structural diagram of an electrolysis device according to an embodiment of the present invention.

[0012] Marked in the figure: 11-electrolytic cell, 111-CEM membrane, 112-anode, 113-cathode, 114-power supply, 115-discharge hopper, 116-solid-liquid separation device, 117-batch tank, 118-dryer, 119-pyrolysis furnace, 120-condenser. DETAILED DESCRIPTION

[0013] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0014] The technical solutions and technical features provided in each section, including the following description, can be combined with each other without conflict. In addition, where possible, these technical solutions, technical features and related combinations can be assigned specific technical themes and protected by relevant patents.

[0015] The embodiments of the present invention involved in the following description are generally only a part of the embodiments rather than all the embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of patent protection.

[0016] Regarding the terms and units in this specification: The terms "include", "comprises", "have" and any variations thereof in this specification and the corresponding claims and related parts are intended to cover non-exclusive inclusions. In addition, other relevant terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0017] Figure 1 FIG. 1 is a schematic diagram of the structure of an electrolysis device according to an embodiment of the present invention. Figure 1 As shown, the electrolysis device comprises an electrolytic cell 11, wherein the electrolytic cell 11 has an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane 111, wherein the anode 112 of the anode liquid tank chamber and the cathode 113 of the cathode liquid tank chamber are respectively connected to the positive and negative electrodes of the power supply 114 of the electrolysis device. The anode liquid used in the anode liquid tank chamber is mainly composed of A X BO4 solution, the cathode liquid used in the cathode liquid tank chamber is AOH solution. A represents a monovalent metal, B represents S element (i.e. sulfur element) or P element (i.e. phosphorus element), x=2 or 3, y=1 or 2, H represents hydrogen element, O represents oxygen element, and OH represents hydroxide ion. During the operation of the electrolytic cell 11, A is produced in the anode liquid tank chamber. y HBO4 crystals, and hydrogen gas and AOH solution with increased concentration are produced in the cathode liquid tank chamber.

[0018] A usually refers to lithium or sodium, so A X BO4 can be sodium sulfate (Na2SO4, at this time x=2), lithium sulfate (Li2SO4, at this time x=2), sodium phosphate (Na3PO4, at this time x=3), lithium phosphate (Li3PO4, at this time x=3). X When BO4 is sodium sulfate or lithium sulfate, A yHBO4 crystals are NaHSO4 crystals or LiHSO4 crystals, and y=1. X When BO4 is sodium phosphate or lithium phosphate, A y The HBO4 crystal is correspondingly Na2HPO4 (sodium monohydrogen phosphate) or Li2HPO4 (lithium monohydrogen phosphate), in which case y=2.

[0019] Sodium sulfate is a common byproduct of some chemical processes. Lithium sulfate, sodium phosphate and lithium phosphate are mainly involved in the lithium battery industry.

[0020] Below is A X BO4 is Na2SO4, AOH is NaOH, A y Taking HBO4 as NaHSO4 as an example, the working principle of the electrolytic cell 11 is described.

[0021] (1) Material input

[0022] Na2SO4 solution is input into the anode liquid tank chamber as the anode liquid, and NaOH solution is input into the cathode liquid tank chamber as the cathode liquid.

[0023] (2) Anode reaction

[0024] Under the action of the external electric field, Na2SO4 in the anolyte is ionized to produce 2Na + and SO4 2- Two parallel oxidation reactions occur at the anode:

[0025] a. Oxygen evolution reaction of water

[0026] 2H2O-4e - →O2↑+4H +

[0027] b. Protonation reaction of sulfate

[0028] SO4 2- +H + →HSO4 -

[0029] HSO4 - +Na + →NaHSO4↓

[0030] (3) CEM membrane migration

[0031] Na + Cations migrate from the anode chamber to the cathode chamber through the CEM membrane, while SO4 2- Anions are blocked and cannot pass through.

[0032] (4) Cathode reaction

[0033] The Na that migrates to the cathode compartment+ The original OH in the cathode chamber - Combined, the concentration of NaOH in the cathode liquid is concentrated.

[0034] The reduction reaction of the cathode to obtain electrons is:

[0035] 2H2O+2e - →H2↑+2OH -

[0036] The cathode reaction produces hydrogen gas and hydroxide ions. The newly generated OH - The Na migrated from the CEM membrane + Combined with, further increase the cathode liquid NaOH concentration.

[0037] (5) Overall reaction equation

[0038] Na2SO4+2H2O→NaHSO4↓+NaOH+(1 / 2)O2↑+H2↑

[0039] It can be seen that the above-mentioned electrolysis device provides a novel idea for treating sodium sulfate and similar substances (such as lithium sulfate, sodium phosphate, lithium phosphate).

[0040] Take the treatment of sodium sulfate as an example: by using an electrolytic cell with a specific structure, sodium sulfate (NaHSO4) crystals can be precipitated in the anode chamber to separate and recycle the sodium salt in the anode liquid; the cathode chamber can produce hydrogen and concentrated sodium hydroxide solution during the electrolysis process. Hydrogen can be used as a clean energy source, and concentrated sodium hydroxide solution can also be used as a chemical raw material. The above electrolytic cell uses CEM membrane as a diaphragm, which can effectively separate the anode and cathode products to prevent them from mixing with each other and affecting the product purity. The CEM membrane only allows the cationic Na + By blocking anions, the independent reaction of the cathode and cathode is ensured. Compared with the traditional salt precipitation process, the separation process of sodium sulfate in this method is changed from evaporation crystallization to electrolytic precipitation, which can reduce energy consumption, and the operating temperature of the electrolysis process is low, the equipment corrosion is small, and it is easy to realize automatic control. By connecting the electrolytic cells in series or in parallel, the process can be enlarged and continuous production can be achieved.

[0041] like Figure 1 As shown, a discharge hopper 115 is provided at the bottom of the anode liquid tank chamber, and a discharge mechanism is provided at the bottom of the discharge hopper 115, and the discharge mechanism is used to discharge the A y HBO4 crystals are discharged from the anode liquid tank chamber. By providing a discharge hopper 115 at the bottom of the anode liquid tank chamber and a discharge mechanism at the bottom of the discharge hopper 115, the A generated in the anode liquid tank chamber can be discharged. y The HBO4 crystals (as NaHSO4) are conveniently discharged from the anolyte chamber.

[0042] In addition, the discharge mechanism is also connected to a solid-liquid separation device 116, which is used to separate the solid and liquid y HBO4 crystals (such as NaHSO4) are used for solid-liquid separation. The solid-liquid separation device 116 is connected to the batching tank 117 through the mother liquid reflux pipeline, and the batching tank 117 is used to prepare the anolyte. Therefore, the mother liquid separated by the solid-liquid separation device 116 will enter the batching tank 117 through the mother liquid reflux pipeline, and then return to the anolyte tank chamber for circulation.

[0043] When the A y When the HBO4 crystals are NaHSO4 crystals, the solid-liquid separation device is connected to the dryer 118, the dryer 118 is connected to the pyrolysis furnace 119, and the pyrolysis furnace 119 is connected to the batching tank 117 and the condenser 120 through the Na2SO4 delivery pipeline and the exhaust pipeline respectively; the dryer 118 is used to dry the NaHSO4 crystals after solid-liquid separation; the pyrolysis furnace 119 is used to pyrolyze the dried NaHSO4 crystals to decompose the NaHSO4 crystals into solid Na2SO4 and gaseous H2SO4 and H2O; the condenser 120 is used to condense the gaseous H2SO4 and H2O to obtain sulfuric acid solution. In this way, both the recycling of sodium sulfate and the production of sulfuric acid can be achieved.

[0044] The present invention provides a water treatment method using the electrolysis device. The water treatment method includes:

[0045] An electrolytic cell 11 is provided, wherein the electrolytic cell 11 has an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane 111, and an anode 112 of the anode liquid tank chamber and a cathode 113 of the cathode liquid tank chamber are respectively connected to the positive and negative electrodes of a power supply 114 of the electrolysis device;

[0046] The anolyte obtained by pre-treatment of raw water and the prepared catholyte are respectively introduced into the anolyte tank chamber and the catholyte tank chamber. The anolyte mainly consists of A X BO4 solution, the cathode liquid is AOH solution;

[0047] As the electrolytic cell operates, A is produced in the anode liquid tank chamber. y HBO4 crystals, and producing hydrogen gas and AOH solution with increased concentration in the cathode liquid tank chamber;

[0048] Among them, A represents a monovalent metal, B represents an S element or a P element, x=2 or 3, y=1 or 2, H represents a hydrogen element, O represents an oxygen element, and OH represents a hydroxide ion.

[0049] Specifically, the anolyte is mainly composed of Na2SO4 solution, the catholyte is NaOH solution, and the A yHBO4 crystals are NaHSO4 crystals.

[0050] In the above method, optionally, the NaHSO4 crystals are subjected to solid-liquid separation, and the mother liquor after the solid-liquid separation is returned to the anode liquid.

[0051] In the above method, optionally, the NaHSO4 crystals after solid-liquid separation are dried and pyrolyzed to decompose the NaHSO4 crystals into solid Na2SO4 and gaseous H2SO4 and H2O, and the gaseous H2SO4 and H2O are condensed to obtain a sulfuric acid solution.

[0052] In the above method, optionally, the anolyte obtained by pre-treating the raw water is a saturated solution of Na2SO4. The saturated solution of Na2SO4 here means that the concentration of Na2SO4 is equal to the solubility of Na2SO4.

[0053] A saturated solution of Na2SO4 that is not oversaturated can continuously precipitate NaHSO4 crystals during the electrolysis process. However, if Na2SO4 is oversaturated, it is easy to crystallize Na2SO4 during transportation and storage, which may cause blockage of pipelines and equipment. The anolyte is prepared into a saturated solution of Na2SO4 that is not oversaturated, which can continuously and efficiently precipitate NaHSO4 crystals during the electrolysis process, while avoiding the crystallization problem during transportation and storage. This is a more reasonable concentration range.

[0054] In the above method, optionally, the Na2SO4 in the anode liquid is a by-product of an upstream chemical process.

[0055] In the above method, optionally, the Na2SO4 in the anolyte is obtained by a method for treating a lithium-containing liquid mineral, wherein the lithium-containing liquid mineral is brine (salt lake brine or underground brine), and the method for treating the lithium-containing liquid mineral specifically comprises:

[0056] The impurity removal step includes adding a precipitant into a sedimentation tank storing a first mother liquor from a raw material tank of brine to precipitate calcium and magnesium in the first mother liquor and performing solid-liquid separation to obtain a second mother liquor;

[0057] A lithium extraction step includes adding a sodium carbonate solution to the second mother liquor to precipitate the lithium in the second mother liquor in the form of lithium carbonate and performing solid-liquid separation to obtain lithium carbonate and a third mother liquor respectively;

[0058] The salt precipitation step comprises adding a sulfuric acid solution into the third mother liquor to obtain a fourth mother liquor containing a Na2SO4 solution;

[0059] The Na2SO4 in the anolyte comes from the fourth mother liquor, and the fourth mother liquor is used as the raw water and is pretreated to obtain the anolyte, or Na2SO4 is extracted from the fourth mother liquor and then configured with the raw water to obtain the anolyte.

[0060] In the process of extracting lithium from lithium-containing liquid minerals such as brine, it is usually necessary to go through steps such as impurity removal, lithium extraction, and salt precipitation. Adding sulfuric acid in the salt precipitation step will generate a large amount of sodium sulfate (Na2SO4) as a byproduct. If this part of sodium sulfate is directly treated as solid waste, it will not only waste resources, but also may cause environmental problems.

[0061] The Na2SO4 solution produced during the treatment of lithium-containing liquid minerals is used as a raw material for the electrolysis device of the present invention, and this part of Na2SO4 can be converted into valuable products such as NaHSO4 crystals, hydrogen and concentrated NaOH solution. NaHSO4 can be used to prepare chemical raw materials such as Na2SO4 and H2SO4, hydrogen can be used as clean energy, and concentrated NaOH solution is also widely used in industry (for example, as a precipitant in the above-mentioned impurity removal process).

[0062] This not only solves the problem of disposing the byproduct Na2SO4 in the development of lithium-containing liquid minerals, realizes the cascade utilization of resources, but also brings additional economic benefits to lithium salt production enterprises. At the same time, the production of clean energy products such as hydrogen through the electrolysis process also reflects the concept of combining the development of lithium-containing liquid minerals with the clean energy industry, which is in line with the development direction of the new energy industry.

[0063] Using the fourth mother liquor as the raw water can simplify the production process, reduce production links, and help reduce energy consumption and operating difficulty.

[0064] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of this specification, all other embodiments obtained by a person skilled in the art without making any creative work shall fall within the scope of patent protection.

Claims

1. A water treatment method, characterized in that: include: An electrolytic cell is provided, wherein the electrolytic cell has an anode liquid tank chamber and a cathode liquid tank chamber separated by a CEM membrane, and the anode of the anode liquid tank chamber and the cathode of the cathode liquid tank chamber are respectively connected to the positive and negative electrodes of a power supply; The anolyte obtained by pre-treatment of raw water and the prepared catholyte are respectively introduced into the anolyte tank chamber and the catholyte tank chamber. The anolyte mainly consists of A X BO4 solution, the cathode liquid is AOH solution; As the electrolytic cell operates, A is produced in the anode liquid tank chamber. y HBO4 crystals, and producing hydrogen gas and AOH solution with increased concentration in the cathode liquid tank chamber; Wherein, A represents a monovalent metal, B represents an S element or a P element, x=2 or 3, y=1 or 2, H represents a hydrogen element, O represents an oxygen element, and OH represents a hydroxide ion; The anolyte is mainly composed of Na2SO4 solution, the catholyte is NaOH solution, y HBO4 crystals are NaHSO4 crystals; The NaHSO4 crystals are subjected to solid-liquid separation, and the mother liquor after solid-liquid separation is returned to the anode liquid; The NaHSO4 crystals after solid-liquid separation are dried and pyrolyzed to decompose the NaHSO4 crystals into solid Na2SO4 and gaseous H2SO4 and H2O, and the gaseous H2SO4 and H2O are condensed to obtain a sulfuric acid solution; Using Na2SO4 obtained by decomposing NaHSO4 crystals as a raw material for preparing the anolyte; The Na2SO4 in the anolyte is obtained by a method for treating a lithium-containing liquid mineral, wherein the lithium-containing liquid mineral is brine, and the method for treating the lithium-containing liquid mineral specifically comprises: The impurity removal step includes adding a precipitant into a sedimentation tank storing a first mother liquor from a raw material tank of brine to precipitate calcium and magnesium in the first mother liquor and performing solid-liquid separation to obtain a second mother liquor; A lithium extraction step includes adding a sodium carbonate solution to the second mother liquor to precipitate the lithium in the second mother liquor in the form of lithium carbonate and performing solid-liquid separation to obtain lithium carbonate and a third mother liquor respectively; The salt precipitation step comprises adding a sulfuric acid solution into the third mother liquor to obtain a fourth mother liquor containing a Na2SO4 solution; The Na2SO4 in the anolyte comes from the fourth mother liquor, and the fourth mother liquor is used as the raw water and is pretreated to obtain the anolyte, or Na2SO4 is extracted from the fourth mother liquor and then configured with the raw water to obtain the anolyte; A discharge hopper is provided at the bottom of the anode liquid tank chamber, and a discharge mechanism is provided at the bottom of the discharge hopper, and the discharge mechanism is used to discharge NaHSO4 from the anode liquid tank chamber; The discharge mechanism is connected to a solid-liquid separation device, and the solid-liquid separation device is connected to a batching tank; the solid-liquid separation device is used to perform solid-liquid separation on NaHSO4; the batching tank is used to prepare anolyte; the solid-liquid separation device and the batching tank are connected via a mother liquid reflux pipeline; The solid-liquid separation device is connected to a dryer, the dryer is connected to a pyrolysis furnace, and the pyrolysis furnace is connected to a batching tank and a condenser through a Na2SO4 delivery pipeline and an exhaust pipeline, respectively; the dryer is used to dry the NaHSO4 crystals after solid-liquid separation; the pyrolysis furnace is used to pyrolyze the dried NaHSO4 crystals to decompose the NaHSO4 crystals into solid Na2SO4 and gaseous H2SO4 and H2O; the condenser is used to condense the gaseous H2SO4 and H2O to obtain a sulfuric acid solution; The anolyte obtained by pretreatment of the raw water is a saturated solution of Na2SO4.

2. The water treatment method according to claim 1, characterized in that: The brine is salt lake brine or underground brine.

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