Electrodialysis method and system for amine recovery

Abstract

This invention relates to an electrodialysis method for recovering amines, comprising the following steps: i) providing a four-chamber electrochemical reaction membrane stack, including an alkali chamber, a product chamber, a feed chamber, and a recovery chamber; ii) providing a two-chamber electrochemical reaction membrane stack, including a recovery chamber purification chamber and a waste chamber; iii) in the four-chamber electrochemical reaction membrane stack, introducing alkali into the alkali chamber, introducing pure water into the product chamber and the recovery chamber, and introducing the feed into the feed chamber; iv) drawing the recovery liquid out of the recovery chamber; v) in the two-chamber electrochemical reaction membrane stack, introducing the recovery liquid into the recovery chamber purification chamber and introducing pure water into the waste chamber; vi) drawing the purified recovery liquid out of the recovery chamber purification chamber; wherein the feed comprises an organic amine compound and a thermally stable salt, and the recovery liquid comprises anions of the organic amine compound and the thermally stable salt. Related systems are also involved. The method and system of this invention can reduce the loss of organic amines during electrodialysis recovery of organic amine compounds.

Description

Technical Field

[0001] This invention belongs to the field of electrodialysis technology, and specifically relates to an electrodialysis method and system for recovering amines. Background Technology

[0002] Currently, various acid gas (e.g., CO2) absorption processes exist, among which the most widely adopted process uses absorbents composed of organic amine compounds to remove acid gases such as carbon dioxide, hydrogen sulfide, and sulfur dioxide from process gas streams. During the absorption of acid gases by organic amine compounds, the degradation of these compounds forms various acids, which in turn react with the organic amine compounds to form a series of amine salts that are difficult to decompose thermally (called thermally stable salts). The presence of thermally stable salts hinders the reuse of organic amines and corrodes equipment. Therefore, it is necessary to remove thermally stable salts from the organic amine solution.

[0003] Electrodialysis is a method for removing thermally stable salts from organic amine solutions. It removes thermally stable salts by allowing the anions (usually various acid radicals) and cations (usually organic amine ions) of the thermally stable salts to move directionally through an ion-selective membrane to other compartments under the action of an electric field.

[0004] However, during electrodialysis desalination, due to the concentration difference between the solutions on both sides of the membrane, electrically neutral organic amine compounds diffuse from the compartment with the higher concentration to the compartment with the lower concentration, driven by the concentration gradient. Although ion-selective membranes are typically designed to minimize the permeation of electrically neutral substances, this cannot be completely avoided. As electrodialysis progresses, the organic amine compounds lost through diffusion due to the concentration gradient accumulate, becoming a significant problem on an industrial scale. Summary of the Invention

[0005] In view of the above problems, the present invention provides an electrodialysis method and system for recovering amines, which can effectively reduce the loss of organic amine compounds during the electrodialysis removal of thermally stable salts.

[0006] According to one aspect of the present invention, an electrodialysis method for recovering amines is provided, comprising the following steps: i) Provide a four-chamber electrochemical reaction membrane stack, including a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, the four-chamber repeating unit including an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, each chamber including an inlet and an outlet; ii) Provide a two-chamber electrochemical reaction membrane stack, including a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit includes a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; iii) In the four-chamber electrochemical reaction membrane stack, alkaline solution is introduced into the alkaline solution chamber, pure water is introduced into the product liquid chamber and the recovery liquid chamber, and raw materials are introduced into the raw material chamber so that pure water is converted into recovery liquid in the recovery liquid chamber; iv) Draw the recovered liquid out of the recovery liquid chamber; v) In the two-chamber electrochemical reaction membrane stack, the recovered liquid is introduced into the recovered liquid purification chamber and pure water is introduced into the waste chamber, so that the recovered liquid is converted into the recovered liquid purified liquid in the recovered liquid purification chamber; vi) Draw out the purified liquid from the purified liquid purification chamber; The raw materials contain organic amine compounds and thermally stable salts, and the recovered liquid contains anions of organic amine compounds and thermally stable salts.

[0007] According to another aspect of the present invention, an electrodialysis system for recovering amines is provided, the electrodialysis system comprising: a) A four-chamber electrochemical reaction membrane stack, comprising a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, wherein the four-chamber repeating unit comprises an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; b) A two-chamber electrochemical reaction membrane stack, comprising a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit comprises a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; The recovery liquid chamber of the four-chamber repeating unit is connected to the recovery liquid purification chamber of the two-chamber repeating unit.

[0008] The electrodialysis method and system for amine recovery provided by this invention takes the technical problem of loss of organic amine compounds caused by concentration gradient diffusion as its starting point. By adopting a specific combination of four-compartment electrodialysis and two-compartment electrodialysis, the technical effect of reducing the loss of organic amine compounds is finally achieved.

[0009] Specifically, the four-compartment repeating unit of "alkali solution chamber - product solution chamber - raw material chamber - recovery solution chamber" provided by this invention confines the concentration difference diffusion of organic amine compounds in the raw material to the product solution and recovery solution in adjacent compartments. Thus, organic amine compounds diffused into the product solution can be reused; after the recovery solution is purified by two-compartment electrodialysis to remove impurity ions, organic amine compounds diffused into the recovery solution can also be reused.

[0010] In the four-compartment electrodialysis of this invention, the specific compartment arrangement of its four-compartment repeating unit utilizes the characteristics of concentration gradient diffusion, confining the concentration gradient diffusion of organic amine compounds in the feed to the product and recovery solutions in adjacent compartments. This allows for the reuse of organic amine compounds that diffuse into the product solution. Furthermore, through the specific membrane arrangement and compartment arrangement of its four-compartment repeating unit, organic amine ions in the feed are directed to the product solution under the influence of an electric field, without moving to the recovery solution. This results in the following beneficial effects: ① Organic amine ions entering the product solution neutralize with hydroxide ions that have directionally migrated from the alkali compartment to the product solution, converting the organic amine ions into organic amine compounds, thus improving the recovery rate of organic amine compounds and reducing their loss; ② The recovery solution, free of organic amine ions, enters the subsequent two-compartment electrodialysis, which helps reduce the wear and tear of the ion exchange membrane in the two-compartment electrodialysis and extends the membrane's lifespan.

[0011] In the case of the two-compartment electrodialysis of this invention, organic amine compounds lost due to concentration gradient diffusion in four-compartment electrodialysis can be recovered. Furthermore, the specific compartment arrangement of the two-compartment repeating unit further reduces the loss of organic amine compounds due to concentration gradient diffusion compared to other numbers of compartments. This is because the "recovery liquid purification chamber-waste chamber" two-compartment repeating unit provided by this invention reduces the loss of effective components (e.g., organic amine compounds) due to forward osmosis compared to existing three-compartment and four-compartment repeating units.

[0012] In summary, the electrodialysis method and system for amine recovery provided by this invention effectively reduce the loss of organic amine compounds during the electrodialysis removal of thermally stable salts. Attached Figure Description

[0013] Figure 1 A schematic diagram of the electrodialysis system of the present invention is shown.

[0014] Figure 2 A schematic diagram of the electrodialysis system of the present invention is shown.

[0015] Figure 3 A schematic diagram of the four-chamber electrochemical reaction membrane stack mentioned in this invention is shown.

[0016] Figure 4A schematic diagram of the two-chamber electrochemical reaction membrane stack mentioned in this invention is shown.

[0017] Figure 5 A schematic diagram of a comparative electrodialysis system is shown.

[0018] Figure 6 A schematic diagram of a comparative electrodialysis system is shown. Detailed Implementation

[0019] To make the invention's purpose, technical solution, and beneficial technical effects clearer, the following will provide a detailed description of the invention.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] Unless otherwise specified, all steps in this application may be performed sequentially, randomly, or simultaneously. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially, or steps (a) and (b) performed simultaneously. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0024] Unless otherwise specified, the terms used in this application have the same meaning as commonly understood by those skilled in the art.

[0025] Unless otherwise specified, the operations mentioned in this application are performed at room temperature and normal pressure.

[0026] Unless otherwise specified, the operations mentioned in this application can be performed in a manner known to those skilled in the art.

[0027] Unless otherwise specified, the equipment, apparatus, instruments, parts, materials, reagents, etc. mentioned in this application can be obtained by means known to those skilled in the art.

[0028] Unless otherwise specified, the indicators mentioned in this application, such as concentration, flow rate, and current density, can be measured by means known to those skilled in the art.

[0029] Unless otherwise specified, the concentrations and proportions of the composition components mentioned in this application are all based on weight.

[0030] Terminology Definition In this article, the term "organic amine solution" refers to a solution containing an organic amine compound. The organic amine compound may also be referred to as an organic amine molecule, denoted as Amin, which exhibits reactivity with the target substance (e.g., an acidic gas).

[0031] In this article, the term "organic amine ion" refers to the interaction between an organic amine molecule and a proton (H+). + The positively charged ions or groups formed by the combination can be described in this paper as AminH + This indicates that it does not exhibit reactivity with the target substance (e.g., acidic gases). Organic amine ions are positively charged and tend to move in a directional manner in an electric field. Organic amine ions can exist as components of stable substances in a bound state or as free ions in a free state.

[0032] In this article, the term "heat stable salt (HSS)," also known as "thermally stable salt" or "thermally stable salt," refers to a type of salt that is not easily decomposed by heat, formed by a series of reactions between organic amine compounds and absorbed acidic gases (such as CO2). The cations constituting heat stable salts are typically protonated organic amines (denoted as AminH) formed from organic amine compounds. + The anions that make up thermally stable salts (denoted as [HSS]) - Depending on the degradation reaction that occurs and the acidic gas absorbed, there can be many types, which are not limited here.

[0033] In this article, the term "cation exchange membrane" refers to a cation exchange membrane that is selectively permeable to cations. The term "anion exchange membrane" refers to anion exchange membrane that is selectively permeable to anions.

[0034] In this article, the term "compartment" (or "chamber") refers to the space formed between the electrode and adjacent ion exchange membranes, and between two adjacent ion exchange membranes, in an electrochemical membrane stack. It is understood that in an electrochemical membrane stack, the electrode and adjacent membranes, and between two adjacent membranes, are not in close contact; space can exist. There are various ways to name a compartment. For example, it can be named according to the substance the compartment is intended to contain during stack operation. For instance, "alkali compartment" refers to a channel in the stack designed to contain alkali; "product compartment" refers to a compartment designed to contain product liquid. Alternatively, it can be named according to the function the compartment is intended to perform during stack operation. For instance, "recovery liquid purification compartment" refers to a compartment in the stack designed to perform the recovery liquid purification function. It is understood that naming based on the contained substance or the performed function does not constitute a unique limitation on the compartment itself; that is, a compartment can be given multiple names, and multiple compartments can be given the same name.

[0035] In this paper, the term "four-compartment repeating unit" (or "four-compartment electrochemical reactor repeating unit") refers to the basic unit that performs the function in a four-compartment electrochemical reactor. These basic units have four compartments, and multiple basic units can be arranged repeatedly. The term "two-compartment repeating unit" (or "two-compartment electrochemical reactor repeating unit") refers to the basic unit that performs the function in a two-compartment electrochemical reactor. These basic units have two compartments, and multiple basic units can be arranged repeatedly.

[0036] This invention provides an electrodialysis method for recovering amines, comprising the following steps: i) Provide a four-chamber electrochemical reaction membrane stack, including a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, the four-chamber repeating unit including an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, each chamber including an inlet and an outlet; ii) Provide a two-chamber electrochemical reaction membrane stack, including a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit includes a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; iii) In the four-chamber electrochemical reaction membrane stack, alkaline solution is introduced into the alkaline solution chamber, pure water is introduced into the product liquid chamber and the recovery liquid chamber, and raw materials are introduced into the raw material chamber so that pure water is converted into recovery liquid in the recovery liquid chamber; iv) Draw the recovered liquid out of the recovery liquid chamber; v) In the two-chamber electrochemical reaction membrane stack, the recovered liquid is introduced into the recovered liquid purification chamber and pure water is introduced into the waste chamber, so that the recovered liquid is converted into the recovered liquid purified liquid in the recovered liquid purification chamber; vi) Draw out the purified liquid from the purified liquid purification chamber; The raw materials contain organic amine compounds and thermally stable salts, and the recovered liquid contains anions of organic amine compounds and thermally stable salts.

[0037] In any embodiment of the present invention, the method of the present invention can be performed continuously or intermittently.

[0038] In any embodiment of the present invention, the method further includes providing an alkali circulation unit, a product liquid circulation unit, a feedstock circulation unit, and a first recovery liquid circulation unit for a four-chamber electrochemical reactor. The alkali circulation unit is configured to circulate alkali between the alkali circulation unit and the alkali chamber; the product liquid circulation unit is configured to circulate pure water between the product liquid circulation unit and the product liquid chamber to obtain product liquid; the feedstock circulation unit is configured to circulate feedstock between the feedstock circulation unit and the feedstock chamber to obtain purified feedstock; and the first recovery liquid circulation unit is configured to circulate pure water between the first recovery liquid circulation unit and the recovery liquid chamber to obtain recovery liquid.

[0039] In any embodiment of the present invention, the method further includes providing a second recovery liquid circulation unit and a waste recycling unit for a two-chamber electrochemical reactor. The second recovery liquid circulation unit is configured to circulate the recovery liquid between the second recovery liquid circulation unit and the recovery liquid purification chamber to obtain purified recovery liquid; the waste recycling unit is configured to circulate pure water between the waste recycling unit and the waste chamber to obtain waste.

[0040] In any embodiment of the present invention, the method further includes drawing out the product liquid from the product liquid chamber, drawing out the purified raw material from the raw material chamber, and drawing out the waste material from the waste material chamber.

[0041] The inventors unexpectedly discovered that, through the specific four-compartment repeating unit of "alkali chamber - product chamber - raw material chamber - recovery chamber" provided by this invention, the concentration difference diffusion of organic amine compounds in the raw material is confined to the product and recovery liquids in adjacent compartments. Therefore, organic amine compounds diffused into the product liquid can be reused; after the recovery liquid is purified by two-compartment electrodialysis to remove impurity ions, organic amine compounds diffused into the recovery liquid can also be reused.

[0042] The organic amine compounds mentioned in this invention can be of types known to those skilled in the art, such as monoamines and polyamines, or, for example, primary amines, secondary amines, tertiary amines, or, for example, straight-chain amines, cyclic amines, and sterically hindered amines. In any embodiment of this invention, the organic amine compound is selected from alkanolamine compounds and piperazine compounds. Preferably, the molecular weight of the alkanolamine compound is less than 500, more preferably less than 300, and the molecular weight of the piperazine compound is less than 500, more preferably less than 300. More preferably, the alkanolamine compound has 2 to 18 carbon atoms, preferably 2 to 12, more preferably 2 to 9, and the piperazine compound has 4 to 22 carbon atoms, preferably 4 to 16, more preferably 4 to 8. In any embodiment of this invention, the organic amine compound is selected from one or more of the following substances: monoethanolamine (MEA, C2H7NO), N-methyldiethanolamine (MDEA, C5H7NO), etc. 13 NO2), diethanolamine (DEA, C4H) 11 NO2), piperazine (PZ, C4H) 10 N2), diethylenetriamine (DETA, C4H) 13 N3), Triethylenetetramine (TETA, C6H) 18 N4), 2-amino-2-methyl-1-propanol (AMP, C4H) 11 NO), N-aminoethylpiperazine (C6H) 15 N3), hydroxyethyl ethylenediamine (AEEA, C4H) 12 ON2), ethylenediamine (EDA, C2H8N2), diisopropanolamine (DIPA, C6HNO2), triethanolamine (TEA, C6H 15 NO3) and 3-diethylaminopropylamine (DEAPA, (C2H5)2N(CH2)3NH2), preferably hydroxyethyl ethylenediamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol and N-aminoethylpiperazine, more preferably hydroxyethyl ethylenediamine and monoethanolamine.

[0043] In any embodiment of the present invention, the initial concentration C of the organic amine compound of the raw material mentioned in the present invention is... O-Amin The concentrations are 20% by weight, 22.5% by weight, 25% by weight, 27.5% by weight, 30% by weight, 32.5% by weight, 35% by weight, 37.5% by weight, 40% by weight, 42.5% by weight, 45% by weight, 47.5% by weight, 50% by weight, 52.5% by weight, 55% by weight, 57.5% by weight, 60% by weight, or any two of the above values, preferably 20-50% by weight, more preferably 20-45% by weight, more preferably 37.5-45% by weight, and even more preferably 42.5-45% by weight. This allows for better recovery of organic amine compounds.

[0044] The thermally stable salts mentioned in this invention can be of types known to those skilled in the art. In any embodiment of this invention, the cation of the thermally stable salt is a protonated organic amine compound as described above, and the anion of the thermally stable salt can be selected from alkyl ions (e.g., formate, acetate, propionate, etc.), halide ions (e.g., chloride, bromide, etc.), pseudohalogen ions (e.g., thiocyanate, etc.), organic oxyacid ions (e.g., carboxylate, alcohol, etc.), and inorganic oxyacid ions (e.g., sulfate, thiosulfate, nitrate, nitrite, etc.). Preferably, the alkyl ion has 1 to 6 carbon atoms, more preferably 1 to 3, and its molecular weight is less than 200, more preferably less than 100; the organic oxyacid ion has 1 to 6 carbon atoms, more preferably 1 to 3, and its molecular weight is less than 200, more preferably less than 100. In any embodiment of the present invention, the cation of the thermally stable salt is selected from one or more of the following substances: protonated monoethanolamine (MEA), N-methyldiethanolamine (MDEA), diethanolamine (DEA), piperazine (PZ), diethylenetriamine (DETA), triethylenetetramine (TETA), 2-amino-2-methyl-1-propanol (AMP), N-aminoethylpiperazine, and 3-diethylaminopropylamine (DEAPA), preferably protonated hydroxyethylethylenediamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, and N-aminoethylpiperazine, more preferably protonated hydroxyethylethylenediamine and monoethanolamine; the anion of the thermally stable salt is selected from one or more of the following ions: formate, acetate, propionate, glycolate, chloride, sulfate, thiocyanate, thiosulfate, nitrate, nitrite, and oxalate; preferably formate, acetate, glycolate, sulfate, oxalate, and chloride.

[0045] In any embodiment of the present invention, the initial concentration C of the thermally stable salt of the raw material mentioned in the present invention... O-HSS The concentrations are 10,000 ppm, 12,000 ppm, 14,000 ppm, 16,000 ppm, 20,000 ppm, 22,000 ppm, 24,000 ppm, 26,000 ppm, 28,000 ppm, 30,000 ppm, 32,000 ppm, 34,000 ppm, 36,000 ppm, or any two of the above values, preferably 10,000 ppm to 30,000 ppm, more preferably 12,000 ppm to 28,000 ppm, and even more preferably 12,000 ppm to 26,000 ppm. This facilitates better removal of heat-stable salts and better recovery of organic amine compounds.

[0046] The alkaline solution mentioned in this invention can be of a type known to those skilled in the art. In any embodiment of this invention, the alkaline solution comprises sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide. In a preferred embodiment of this invention, the alkaline solution is a sodium hydroxide solution.

[0047] In any embodiment of the present invention, the initial equivalent concentration of the alkaline solution mentioned in the present invention is 2~3.5 N. This facilitates better removal of heat-stable salts and better recovery of organic amine compounds.

[0048] In any embodiment of the present invention, the concentration C of the organic amine compound in the recovered liquid mentioned in the present invention R-Amin The concentration can be 10 wt%, 12.5 wt%, 15 wt%, 17.5 wt%, 20 wt%, 22.5 wt%, 25 wt%, 27.5 wt%, 30 wt%, 32.5 wt%, 35 wt%, 37.5 wt%, 40 wt%, 42.5 wt%, 45 wt%, 47.5 wt%, 50 wt%, or any two of the above values, preferably 12.5-45 wt%, more preferably 15-45 wt%, and even more preferably 20-45 wt%. This is beneficial for achieving better removal of thermally stable salts and better recovery of organic amine compounds.

[0049] In any embodiment of the present invention, the thermal stability salt concentration C of the recovered liquid mentioned in the present invention R-HSS The concentrations are 300,000 ppm, 350,000 ppm, 400,000 ppm, 450,000 ppm, 500,000 ppm, 550,000 ppm, 600,000 ppm, 650,000 ppm, 700,000 ppm, 750,000 ppm, 800,000 ppm, 850,000 ppm, 900,000 ppm, or any two of the above values, preferably 400,000 ppm to 800,000 ppm, more preferably 650,000 ppm to 800,000 ppm. This facilitates better removal of thermally stable salts and better recovery of organic amine compounds.

[0050] In any embodiment of the present invention, when the concentration ratio C of the organic amine compound in the recovered liquid to that in the raw material is... R-Amin / C O-AminWhen the concentration is higher than 0.40, preferably 0.45, more preferably 0.50, more preferably 0.55, more preferably 0.60, more preferably 0.65, more preferably 0.70, more preferably 0.75, more preferably 0.80, more preferably 0.85, the recovered liquid is drawn out from the recovered liquid chamber. This facilitates better removal of thermally stable salts and better recovery of organic amine compounds. Preferably, when the concentration ratio C of organic amine compounds in the recovered liquid to that in the raw material is... R-Amin / C O-Amin Within the range of 0.85 to 0.95, the recovered liquid is drawn from the recovery chamber. This facilitates the balance between the removal of thermally stable salts, the recovery of organic amine compounds, and energy efficiency.

[0051] In any embodiment of the present invention, when the thermally stable salt content C in the recovered liquid and purified liquid is... P-HSS When the concentration is below 5000 ppm, preferably 4000 ppm, more preferably 3000 ppm, even more preferably 2000 ppm, even more preferably 1000 ppm, even more preferably 500 ppm, even more preferably 400 ppm, even more preferably 300 ppm, the purified liquid is drawn from the purified liquid collection chamber. This facilitates better removal of thermally stable salts. Preferably, when the thermally stable salt content in the purified liquid is in the range of 200-300 ppm, more preferably 250-300 ppm, the purified liquid is drawn from the purified liquid collection chamber. This facilitates a balance between the removal of thermally stable salts, the recovery of organic amine compounds, and energy efficiency.

[0052] In any embodiment of the present invention, the four-chamber electrochemical reaction membrane stack may include a plurality of four-chamber repeating units disposed between the first cathode chamber and the first anode chamber, and the plurality of four-chamber repeating units may be arranged sequentially.

[0053] Regarding the four-chamber repeating unit mentioned in this invention, the compartments are arranged from the first cathode chamber to the first anode chamber as an alkali chamber, a product chamber, a raw material chamber, and a recovery liquid chamber (or referred to as "alkali chamber-product chamber-raw material chamber-recovery liquid chamber"). From the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery liquid chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane. More specifically, in the four-chamber repeating unit, the alkali chamber from the first cathode chamber to the first anode chamber is defined by a cation membrane and an anion membrane; the product chamber from the first cathode chamber to the first anode chamber is defined by an anion membrane and a cation membrane; the raw material chamber from the first cathode chamber to the first anode chamber is defined by a cation membrane and an anion membrane; and the recovery liquid chamber from the first cathode chamber to the first anode chamber is defined by an anion membrane and a cation membrane.

[0054] In any embodiment of the present invention, the four-chamber repeating unit consists only of an alkali chamber, a product chamber, a raw material chamber, and a recovery chamber, excluding other compartments.

[0055] In the four-chamber electrochemical membrane stack mentioned in this invention, the first cathode chamber is defined by a first cathode plate and an ion exchange membrane, and the first anode chamber is defined by a first anode plate and an ion exchange membrane. Preferably, the first cathode chamber is defined by a first cathode plate and an ion exchange membrane, and / or the first anode chamber is defined by a first anode plate and an ion exchange membrane. This reduces or even prevents anions from the electrode solution from entering the four-chamber electrodialysis solution system, which is beneficial for maintaining the ion concentration and conductivity of the electrode solution, and also helps to reduce or even avoid contamination of the four-chamber electrodialysis solution system by the electrode solution.

[0056] In any embodiment of the present invention, the four-chamber electrochemical reaction membrane stack may include, in addition to the four-chamber repeating unit, a first transition compartment adjacent to the first cathode chamber or the first anode chamber, so that the first cathode chamber or the first anode chamber is not adjacent to the four-chamber repeating unit, thereby reducing or even preventing ions in the electrode solution from entering the product chamber, feed chamber, and / or recovery chamber. In any embodiment of the present invention, the alkali chamber may serve as the first transition compartment.

[0057] In any embodiment of the present invention, in the four-chamber electrochemical reaction membrane stack, the first cathode chamber and / or the first anode chamber are adjacent to the alkali chamber via a cation membrane. This reduces or even prevents anions from the electrode solution from entering the product solution and / or the purified feed / recovery solution, which on the one hand helps maintain the ion concentration and conductivity of the electrode solution, and on the other hand helps reduce or even avoid contamination of the product solution and / or the purified feed / recovery solution by the electrode solution.

[0058] The electrode liquid in the four-compartment electrochemical reactor mentioned in this invention can be of a type known to those skilled in the art, such as sodium sulfate or sodium hydroxide. In any embodiment of this invention, the electrode liquid and the alkali solution in the four-compartment electrochemical reactor are of the same type, for example, both the electrode liquid and the alkali solution are sodium hydroxide solutions. Therefore, even if ions from the electrode liquid enter the four-compartment electrodialysis solution system, they will not act as impurity ions and cause contamination.

[0059] In any embodiment of the present invention, the four-chamber electrochemical reactor can be as follows: Figure 3 In the example, the cation exchange membrane is represented by membrane C, the anion exchange membrane by membrane A, and "..." in the diagram represents other ion exchange membranes that can exist and the compartments they form. "+" and "-" represent the positive and negative electrodes, respectively. Figure 3 As an example, an alkaline solution is introduced into the alkaline solution chamber 12, pure water is introduced into the product liquid chamber 13 and the recovery liquid chamber 11, and the raw material is introduced into the raw material chamber 14. The alkaline solution is, for example, a NaOH solution, and the raw material contains a thermally stable salt (denoted as AminH). + [HSS] - ) and organic amine compounds (denoted as Amin). Under the influence of an electric field, the cations AminH in the four-compartment electrodialysis system + Na+ Anions [HSS] migrate towards the cathode. - and OH - Migrating towards the anode. Simultaneously, under the influence of the concentration gradient, electrically neutral Amin migrates through the ion exchange membrane to adjacent compartments. Considering the combined effects of the electric field, concentration gradient, and the confinement effect of the ion exchange membrane, the main flow directions of substances in each compartment can be summarized as follows: Alkali chamber 12: Na migration + and OH - ; Product chamber 13: Amin and AminH migrated in. + and OH - ; Raw material chamber 14: Amin and AminH migrate out + and [HSS] - ; Recovery chamber 11: Migrating Amin, Na + and [HSS] - .

[0060] In the alkaline solution chamber 12, it can be assumed that as electrodialysis proceeds, Na... + and OH - The concentration of OH- in the alkaline solution continuously decreases. - When the concentration requirement is met (e.g., below a specific concentration), the alkali solution in the alkali solution chamber can be replaced, or alkaline substances can be added to the alkali solution.

[0061] In product chamber 13, the following reaction can be considered to occur: AminH + +OH - →Amin + H₂O causes the thermally stable salt cations entering the pure water to react with hydroxide ions and be converted into organic amine compounds. Simultaneously, electrically neutral organic amine compounds diffuse into the pure water through the concentration gradient. Thus, the pure water is gradually converted into the product liquid. When the concentration of organic amine compounds in the product liquid meets the requirements (e.g., above a specific concentration), the product liquid can be drawn out from the product liquid chamber.

[0062] In the raw material chamber 14, it can be assumed that as electrodialysis proceeds, more and more thermally stable salts are removed, thus purifying the raw material. When the concentration requirements of thermally stable salts in the raw material are met (e.g., below a specific concentration or reaching a specific concentration ratio), the purified raw material can be drawn out from the raw material chamber.

[0063] In the recovery chamber 11, it can be assumed that while electrodialysis is proceeding, an increasing number of electrically neutral organic amine compounds diffuse into the pure water through the concentration gradient. This gradually transforms the pure water into the recovery liquid. When the concentration of organic amine compounds in the recovery liquid meets the requirements (e.g., higher than a specific concentration, reaching a specific concentration ratio), the recovery liquid can be drawn out from the recovery chamber.

[0064] In the four-compartment electrodialysis of this invention, the specific compartment arrangement of its four-compartment repeating unit utilizes the characteristics of concentration gradient diffusion, confining the concentration gradient diffusion of organic amine compounds in the feed to the product and recovery solutions in adjacent compartments. This allows for the reuse of organic amine compounds that diffuse into the product solution. Furthermore, through the specific membrane arrangement and compartment arrangement of its four-compartment repeating unit, organic amine ions in the feed are directed to the product solution under the influence of an electric field, without moving to the recovery solution. This results in the following beneficial effects: ① Organic amine ions entering the product solution neutralize with hydroxide ions that have directionally migrated from the alkali compartment to the product solution, converting the organic amine ions into organic amine compounds, thus improving the recovery rate of organic amine compounds and reducing their loss; ② The recovery solution, free of organic amine ions, enters the subsequent two-compartment electrodialysis, which helps reduce the wear and tear of the ion exchange membrane in the two-compartment electrodialysis and extends the membrane's lifespan.

[0065] The recovered liquid drawn from the recovery liquid chamber is optionally treated with concentration and / or impurity removal before being introduced into the recovery liquid purification chamber of the two-chamber electrochemical reaction membrane stack. The concentration and / or impurity removal mentioned in this invention can be carried out using conventional methods and equipment known to those skilled in the art.

[0066] In any embodiment of the present invention, the two-compartment electrochemical reaction membrane stack may include a plurality of two-compartment repeating units disposed between the second cathode chamber and the second anode chamber, and the plurality of two-compartment repeating units may be arranged sequentially.

[0067] Regarding the two-chamber repeating unit mentioned in this invention, the compartments are arranged from the second cathode chamber to the second anode chamber as a recovery liquid purification chamber and a waste chamber (or referred to as "recovery liquid purification chamber-waste chamber"), wherein the recovery liquid purification chamber is defined by a cation membrane and an anion membrane from the second cathode chamber to the second anode chamber; the waste chamber is defined by an anion membrane and a cation membrane from the second cathode chamber to the second anode chamber.

[0068] In any embodiment of the present invention, the two-chamber repeating unit consists only of a recovery liquid purification chamber and a waste chamber, and does not include other compartments.

[0069] In the two-compartment electrochemical membrane stack mentioned in this invention, the second cathode compartment is defined by a second cathode plate and an ion exchange membrane, preferably by a second cathode plate and an ion exchange membrane; the second anode compartment is defined by a second anode plate and an ion exchange membrane, preferably by a second anode plate and an ion exchange membrane. This reduces or even prevents anions from the electrode solution from entering the two-compartment electrodialysis solution system, which on the one hand helps maintain the ion concentration and conductivity of the electrode solution, and on the other hand helps reduce or even avoid contamination of the two-compartment electrodialysis solution system by the electrode solution.

[0070] In any embodiment of the present invention, the two-chamber electrochemical reaction membrane stack may include a second transition compartment adjacent to the second cathode chamber or the second anode chamber, in addition to the two-chamber repeating unit, so that the second cathode chamber or the second anode chamber is not adjacent to the two-chamber repeating unit, thereby reducing or even preventing ions in the electrode solution from entering the recovery liquid purification chamber. In any embodiment of the present invention, the waste chamber may serve as the second transition compartment.

[0071] In any embodiment of the present invention, in the two-chamber electrochemical reaction membrane stack, the second cathode chamber and / or the second anode chamber are adjacent to the waste chamber via a cation membrane. This reduces or even prevents anions from the electrode solution from entering the recovery and purification solutions, which is beneficial for maintaining the ion concentration and conductivity of the electrode solution, and also helps to reduce or even avoid contamination of the recovery and purification solutions by the electrode solution.

[0072] The electrode liquid of the two-chamber electrochemical reaction membrane stack mentioned in this invention can be of a type known to those skilled in the art, such as sodium sulfate, sodium hydroxide, etc.

[0073] In any embodiment of the present invention, the electrode solution of the four-chamber electrochemical reactive membrane stack is the same as that of the two-chamber electrochemical reactive membrane stack. This allows for a unified supply of electrode solution to both the four-chamber and two-chamber electrochemical reactive membrane stacks, thereby reducing costs.

[0074] In any embodiment of the present invention, the electrode liquid (electrolyte of the four-chamber electrochemical reactor and / or the electrode liquid of the two-chamber electrochemical reactor) mentioned in the present invention is of the same type as the alkaline solution. This reduces electrode liquid contamination of the alkaline solution and allows for a unified supply of electrode liquid to the four-chamber electrochemical reactor and / or the two-chamber electrochemical reactor, thereby reducing costs.

[0075] In any embodiment of the present invention, the two-compartment electrochemical reactor can be as follows: Figure 4 In the example shown, the cation exchange membrane is represented by membrane C, the anion exchange membrane by membrane A, and "..." in the figure represents other ion exchange membranes that can exist and the compartments they form. "+" and "-" represent the positive and negative electrodes, respectively. As illustrated, the recovered liquid is introduced into the recovered liquid purification chamber 21, and pure water is introduced into the waste chamber 22. The recovered liquid contains Aminochloride (Amin) and Na+. + and [HSS] - (Taking the aforementioned four-compartment electrochemical reactor using NaOH solution as an example). Under the influence of an electric field, the cations Na in the two-compartment electrodialysis system... + Anions [HSS] migrate towards the cathode. - Migrating towards the anode. Simultaneously, under the influence of the concentration gradient, electrically neutral Amin migrates through the ion exchange membrane to adjacent compartments. Considering the combined effects of the electric field, concentration gradient, and the confinement effect of the ion exchange membrane, the main flow directions of substances in each compartment can be summarized as follows: Recovery liquid purification chamber 21: Migration of Amin, Na + and [HSS] - ; Waste Chamber 22: Introducing Amin and Na + and [HSS] - .

[0076] In the recovery liquid purification chamber 21, it can be assumed that as electrodialysis proceeds, more and more Na... + and [HSS] - The removal of these compounds purifies the recovered liquid. Simultaneously, the amount of organic amine compounds in the recovered liquid also decreases, but compared to ion migration under an electric field, the concentration gradient diffusion of electrically neutral organic amine compounds is significantly less. Since the directional movement of ions carries a certain number of water molecules with it, Na... + And / or [HSS] - The concentration of sodium in the recovered solution will decrease, while the concentration of organic amine compounds in the recovered solution will increase. This gradually transforms the recovered solution into a purified recovered solution. When the sodium concentration in the purified recovered solution... + And / or [HSS] - When the concentration requirements are met (e.g., below a specific concentration or reaching a specific concentration ratio) and / or the organic amine compounds in the recovered liquid and purified liquid meet the concentration requirements (e.g., above a specific concentration or reaching a specific concentration ratio), the recovered liquid and purified liquid can be extracted.

[0077] In waste chamber 22, it can be assumed that as electrodialysis proceeds, Na... + and [HSS] - The amount of Na in the waste continues to increase. + And / or [HSS] - When the concentration requirements are met (e.g., higher than a specific concentration or reaching a specific concentration ratio), the waste can be drawn out from the waste chamber.

[0078] In the case of the two-compartment electrodialysis of this invention, organic amine compounds lost due to concentration gradient diffusion in four-compartment electrodialysis can be recovered. Furthermore, the specific compartment arrangement of the two-compartment repeating unit further reduces the loss of organic amine compounds due to concentration gradient diffusion compared to other numbers of compartments. This is because the "recovery liquid purification chamber-waste chamber" two-compartment repeating unit provided by this invention reduces the loss of effective components (e.g., organic amine compounds) due to forward osmosis compared to existing three-compartment and four-compartment repeating units.

[0079] In the electrodialysis method of the present invention, the anion and cation exchange membranes mentioned can be one or more anion and cation exchange membranes known to those skilled in the art, and can be obtained or prepared in a manner known to those skilled in the art.

[0080] In any embodiment of the present invention, the types of anion membranes and / or cation membranes used in the four-compartment electrochemical reactor and the two-compartment electrochemical reactor may be the same or different.

[0081] In the electrodialysis method of the present invention, the first cathode plate, the second cathode plate, the first anode plate, and the second anode plate mentioned can be one or more cathode and anode plates known to those skilled in the art, and can be obtained or prepared in a manner known to those skilled in the art.

[0082] In any embodiment of the present invention, the first cathode plate and / or the second cathode plate and / or the first anode plate and / or the second anode plate may be the same or different.

[0083] In any embodiment of the present invention, the first cathode plate and / or the second cathode plate and / or the first anode plate and / or the second anode plate may be selected from one or more of titanium plates and titanium-plated plates.

[0084] The method of the present invention further includes applying voltages to the anode and cathode plates to generate an electric field. The anode and cathode plates of the electrochemical reaction membrane stack are connected to an external power source, thereby providing an electric field to the membrane stack during device operation, causing the anions and cations to move directionally within the membrane stack.

[0085] In any embodiment of the present invention, the current density of the four-chamber electrochemical reactive membrane stack ranges from 50 to 450 A / m. 2 Preferred A / m 2 Reaction within this current density range is beneficial for improving desalination efficiency and reducing the overall loss of organic amine compounds in the electrodialysis process of this invention.

[0086] In any embodiment of the present invention, the current density of the two-compartment electrochemical reactive membrane stack ranges from 100 to 400 A / m. 2 Preferred 160-280A / m 2 Reaction within this current density range is beneficial for improving desalination efficiency and reducing the overall loss of organic amine compounds in the electrodialysis process of this invention.

[0087] In any embodiment of the present invention, the current density ratio of the four-compartment electrochemical reaction membrane stack to the two-compartment electrochemical reaction membrane stack is (0.3~2.3):1, preferably (0.4~2.0):1. This is beneficial for improving desalination efficiency and reducing the overall loss of organic amine compounds in the electrodialysis process of the present invention.

[0088] In any embodiment of the present invention, the method of the present invention includes: iii) in a four-chamber electrochemical reaction membrane stack, introducing alkaline solution into an alkaline solution chamber, introducing pure water into a product liquid chamber and a recovery liquid chamber, and introducing raw material into a raw material chamber, so that pure water is converted into product liquid in the product liquid chamber, pure water is converted into recovery liquid in the recovery liquid chamber, and raw material is converted into purified raw material in the raw material chamber; iv) drawing recovery liquid from the recovery liquid chamber, drawing product liquid from the product liquid chamber to a collection tank, and drawing purified raw material from the raw material chamber to a collection tank; vi) drawing purified recovery liquid from the recovery liquid purification chamber to a collection tank.

[0089] In any embodiment of the present invention, the liquid flow rates in the four-chamber electrochemical reaction membrane stack and / or the two-chamber electrochemical reaction membrane stack can be set in a manner known to those skilled in the art, and are not particularly limited herein.

[0090] The present invention also provides an electrodialysis system for recovering amines, the electrodialysis system comprising: a) A four-chamber electrochemical reaction membrane stack, comprising a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, wherein the four-chamber repeating unit comprises an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; b) A two-chamber electrochemical reaction membrane stack, comprising a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit comprises a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; The recovery liquid chamber of the four-chamber repeating unit is connected to the recovery liquid purification chamber of the two-chamber repeating unit.

[0091] In any embodiment of the present invention, the electrodialysis system may further include: c) A first recovery liquid circulation tank, used to circulate the recovery liquid between the first recovery liquid circulation tank and the recovery liquid chamber; the outlet of the first recovery liquid circulation tank is connected to the inlet of the recovery liquid chamber, and the outlet of the recovery liquid chamber is connected to the inlet of the first recovery liquid circulation tank via a first recovery liquid return valve. d) A second recovery liquid circulation tank is used to circulate the recovery liquid between the second recovery liquid circulation tank and the recovery liquid purification chamber; the outlet of the second recovery liquid circulation tank is connected to the inlet of the recovery liquid purification chamber, and the outlet of the recovery liquid purification chamber is connected to the inlet of the second recovery liquid circulation tank. The outlet of the recovery liquid chamber of the four-chamber electrochemical reaction membrane stack is connected to the inlet of the second recovery liquid circulation tank via a second recovery liquid reflux valve. The electrodialysis system includes a first state and a second state that can be switched between each other. In the first state, the recovery liquid chamber is only connected to the first recovery liquid circulation tank. In the second state, the inlet of the recovery liquid chamber is only connected to the outlet of the first recovery liquid circulation tank, and the outlet of the recovery liquid chamber is only connected to the inlet of the second recovery liquid circulation tank.

[0092] In any embodiment of the invention, the electrodialysis system may further include several pumps to provide a power source for the flow of liquid.

[0093] The inventors unexpectedly discovered that, through the specific four-compartment repeating unit of "alkali chamber - product chamber - raw material chamber - recovery chamber" provided by this invention, the concentration difference diffusion of organic amine compounds in the raw material is confined to the product and recovery liquids in adjacent compartments. Therefore, organic amine compounds diffused into the product liquid can be reused; after the recovery liquid is purified by two-compartment electrodialysis to remove impurity ions, organic amine compounds diffused into the recovery liquid can also be reused.

[0094] In any embodiment of the invention, the electrodialysis system further includes an electrode fluid circulation tank for circulating the electrode fluid between the electrode fluid circulation tank and a first cathode chamber and / or a first anode chamber and / or a second cathode chamber and / or a second anode chamber; the electrode fluid circulation tank includes an inlet and an outlet, the outlet of which is connected to the inlet of the first cathode chamber and / or the inlet of the first anode chamber via a first electrode fluid circulation valve, and to the inlet of the second cathode chamber and / or the inlet of the second anode chamber via a second electrode fluid circulation valve; the outlet of the first cathode chamber and / or the outlet of the first anode chamber is connected to the inlet of the electrode fluid circulation tank via a first electrode fluid return valve, and the outlet of the second cathode chamber and / or the outlet of the second anode chamber is connected to the inlet of the electrode fluid circulation tank via a second electrode fluid return valve; the electrodialysis system includes a third state and a fourth state that can be switched between each other, in the third state, the electrode fluid circulation tank is only in communication with the first cathode chamber and / or the first anode chamber; in the fourth state, the electrode fluid circulation tank is in communication with both the first cathode chamber and / or the first anode chamber and the second cathode chamber and / or the second anode chamber. Therefore, the electrode liquid can be uniformly supplied to both the four-chamber electrochemical reactor and the two-chamber electrochemical reactor, thereby reducing costs.

[0095] In any embodiment of the present invention, the four-chamber electrochemical reaction membrane stack may include, in addition to the four-chamber repeating unit, a first transition compartment adjacent to the first cathode chamber or the first anode chamber, so that the first cathode chamber or the first anode chamber is not adjacent to the four-chamber repeating unit, thereby reducing or even preventing ions in the electrode solution from entering the product chamber, feed chamber, and / or recovery chamber. In any embodiment of the present invention, the alkali chamber may serve as the first transition compartment.

[0096] In any embodiment of the present invention, in the four-chamber electrochemical reaction membrane stack, the first cathode chamber and / or the first anode chamber are adjacent to the alkali chamber via a cation exchange membrane. This reduces or even prevents anions from the electrode solution from entering the product solution and / or the purified feed / recovery solution, which on the one hand helps maintain the ion concentration and conductivity of the electrode solution, and on the other hand helps reduce or even avoid contamination of the product solution and / or the purified feed / recovery solution by the electrode solution.

[0097] In any embodiment of the present invention, the two-chamber electrochemical reaction membrane stack may include a second transition compartment adjacent to the second cathode chamber or the second anode chamber, in addition to the two-chamber repeating unit, so that the second cathode chamber or the second anode chamber is not adjacent to the two-chamber repeating unit, thereby reducing or even preventing ions in the electrode solution from entering the recovery liquid purification chamber. In any embodiment of the present invention, the waste chamber may serve as the second transition compartment.

[0098] In any embodiment of the present invention, in the two-chamber electrochemical reaction membrane stack, the second cathode chamber and / or the second anode chamber are adjacent to the waste chamber via a cation membrane. This reduces or even prevents anions from the electrode solution from entering the recovery and purification solutions, which is beneficial for maintaining the ion concentration and conductivity of the electrode solution, and also helps to reduce or even avoid contamination of the recovery and purification solutions by the electrode solution.

[0099] In any embodiment of the present invention, the electrodialysis system further includes: e) an alkali circulation tank connected to an alkali chamber for circulating alkali between the alkali circulation tank and the alkali chamber; f) a product circulation tank connected to a product chamber for circulating product between the product circulation tank and the product chamber; and g) a raw material circulation tank connected to a raw material chamber for circulating raw material between the raw material circulation tank and the raw material chamber.

[0100] In any embodiment of the present invention, the electrodialysis system further includes a collection tank (h) for collecting product liquid from the product liquid chamber, purified raw material from the raw material chamber, and purified liquid from the recycled liquid purification chamber.

[0101] In any embodiment of the present invention, the electrodialysis system further includes: i) a waste circulation tank connected to the waste chamber for circulating waste between the waste circulation tank and the waste chamber.

[0102] In any embodiment of the present invention, the electrodialysis system of the present invention can be exemplarily as follows: Figure 1As shown, the labels represent: 1-Four-chamber electrochemical reactor; 101-First recovery liquid circulation tank; 1012-First recovery liquid circulation pump; 1013-First recovery liquid reflux valve; 102-Alkali circulation tank; 1022-Alkali circulation pump; 103-Product liquid circulation tank; 1032-Product liquid circulation pump; 104-Raw material circulation tank; 1042-Raw material circulation pump; 105-Electrode liquid circulation tank; 1052-Electrode liquid circulation pump; 1053-First electrode liquid circulation valve; 1054-First electrode liquid reflux valve; 1055-Second electrode liquid reflux valve; 1056-Second electrode liquid circulation valve; 2-Two-chamber electrochemical reactor; 201-Second recovery liquid circulation tank; 2012-Second recovery liquid circulation pump; 2014-Second recovery liquid reflux valve; 202-Waste material circulation tank; 2022-Waste material circulation pump.

[0103] In this invention, the anion and cation exchange membranes mentioned can be one or more anion and cation exchange membranes known to those skilled in the art, and can be obtained or prepared in a manner known to those skilled in the art. Anion and cation exchange membranes can be used to restrict ion migration, thereby confining ion migration to a desired spatial range.

[0104] In this invention, the various circulation tanks mentioned (e.g., the first recovery liquid circulation tank, the second recovery liquid circulation tank, the electrode liquid circulation tank, etc.) can be selected from commercially available models or manufactured by methods known to those skilled in the art, and are used to contain the various liquids (e.g., recovery liquid, electrode liquid, etc.) mentioned in the method of this invention. The material of the circulation tank can be a material known for use in the field of electrodialysis, such as plastic, metal, etc.

[0105] In this invention, the electrodialysis system may further include several valves to control the start and stop of liquid flow. The valves mentioned (e.g., a first recovery liquid reflux valve, a second recovery liquid reflux valve, a first electrode liquid circulation valve, a second electrode liquid circulation valve, a first electrode liquid reflux valve, a second electrode liquid reflux valve, etc.) can be selected from commercially available models or manufactured using methods known to those skilled in the art, and are used to control the opening and closing of the pipeline. The valves can be made of materials known for use in the field of electrodialysis, such as plastics, metals, etc.

[0106] In this invention, the electrodialysis system may further include several pumps to provide a power source for the flow of liquid. These pumps may be selected from commercially available models or manufactured in a manner known to those skilled in the art. The pumps may be made of materials known for use in the field of electrodialysis, such as plastics or metals.

[0107] The electrodialysis system of the present invention may further include several pipes, which may be selected from commercially available models or manufactured by methods known to those skilled in the art, for connecting the various components within the system. The pipes may be made of materials known for use in the field of electrodialysis, such as plastics, metals, etc.

[0108] The connection mentioned in this invention can adopt connection methods known to those skilled in the art for use in the field of electrodialysis devices, such as welding connection, threaded connection, pin connection, riveting connection, etc.

[0109] The method and system of the present invention will be described below with reference to the accompanying drawings: Figure 2 A schematic diagram of an electrodialysis system according to one embodiment of the present invention is shown, wherein the compartmentalized structure inside the four-compartment electrochemical reaction membrane stack and the two-compartment electrochemical reaction membrane stack is not shown in the figure. Figure 2 Compared to Figure 1 In addition, a discharge pipeline for discharging liquid material, a collection pipeline for collecting liquid material, and their matching valves and pumps have been added. Figure 2 The symbols are as follows: 1-Four-chamber electrochemical reactor; 101-First recovery liquid circulation tank; 1011-First recovery liquid circulation valve; 1012-First recovery liquid circulation pump; 1013-First recovery liquid reflux valve; 102-Alkali circulation tank; 1021-Alkali circulation valve; 1022-Alkali circulation pump; 103-Product liquid circulation tank; 1031-First product liquid circulation valve; 1032-Product liquid circulation pump; 1033-Second product liquid circulation valve; 1034-Product liquid collection valve; 104-Feed circulation tank; 1041-First feedstock circulation valve; 1042-Feedstock circulation pump; 1043-Second feedstock circulation valve; 1044-Feedstock collection valve Valve; 105-Electrode liquid circulation tank; 1051-Electrode liquid outlet valve; 1052-Electrode liquid circulation pump; 1053-First electrode liquid circulation valve; 1054-First electrode liquid reflux valve; 1055-Second electrode liquid reflux valve; 1056-Second electrode liquid circulation valve; 2-Two-chamber electrochemical reaction membrane stack; 201-Second recovery liquid circulation tank; 2011-Second recovery liquid circulation valve; 2012-Second recovery liquid circulation pump; 2013-Third recovery liquid circulation valve; 2014-Second recovery liquid reflux valve; 2015-Recovery liquid purification liquid collection valve; 202-Waste recycling tank; 2021-Waste recycling valve; 2022-Waste recycling pump.

[0110] Figure 3 An exemplary schematic diagram of the internal structure of the four-compartment electrochemical reaction membrane stack for electrodialysis of the present invention is shown. In the diagram, the cation exchange membrane is represented by membrane C, the anion exchange membrane by membrane A, "..." indicates other possible ion exchange membranes and the compartments they form, and "+" and "-" represent the positive and negative electrodes, respectively. The reference numerals are as follows: 11-Recovery liquid chamber; 12-Alkali liquid chamber; 13-Production liquid chamber; 14-Raw material chamber; 151-First cathode chamber; 152-First anode chamber.

[0111] Figure 4An exemplary schematic diagram of the internal structure of the two-compartment electrochemical reaction membrane stack for electrodialysis of the present invention is shown. In the diagram, the cation exchange membrane is represented by membrane C, the anion exchange membrane by membrane A, "..." indicates other ion exchange membranes that may exist and the compartments they form, and "+" and "-" indicate the positive and negative electrodes, respectively. The reference numerals are as follows: 21 - Recovery liquid purification chamber; 22 - Waste chamber; 251 - Second cathode chamber; 252 - Second anode chamber.

[0112] Reference Figure 2 The following explanation is provided. When implementing the method and system of this invention, the first recovered liquid circulation valve 1011, the first recovered liquid circulation pump 1012, and the first recovered liquid return valve 1013 are in the open state, while the second recovered liquid return valve 2014 is in the closed state (i.e., the first state, where the recovered liquid chamber 11 is only connected to the first recovered liquid circulation tank 101). This allows pure water from the first recovered liquid circulation tank 101 to be introduced into the recovered liquid chamber 11 and circulate between the first recovered liquid circulation tank 101 and the recovered liquid chamber 11. The alkali circulation valve 1021 and the alkali circulation pump 1022 are in the open state, allowing alkali from the alkali circulation tank 102 to be introduced into the alkali chamber 12 and circulate between the alkali circulation tank 102 and the alkali chamber 12. The first product circulation valve 1031, product circulation pump 1032, and second product circulation valve 1033 are opened, while the product collection valve 1034 is closed, allowing pure water from the product circulation tank 103 to be introduced into the product chamber 13 and circulate between the product circulation tank 103 and the product chamber 13. The first raw material circulation valve 1041, raw material circulation pump 1042, and second raw material circulation valve 1043 are opened, while the raw material collection valve 1044 is closed, allowing raw material from the raw material circulation tank 104 to be introduced into the raw material chamber 14 and circulate between the raw material circulation tank 104 and the raw material chamber 14. The electrode liquid outlet valve 1051, electrode liquid circulation pump 1052, first electrode liquid circulation valve 1053, and first electrode liquid return valve 1054 are in the open state, and the second electrode liquid return valve 1055 and second electrode liquid circulation valve 1056 are in the closed state (i.e., the third state, the electrode liquid circulation tank 105 is only connected to the first cathode chamber 151 and the first anode chamber 152), so that the electrode liquid in the electrode liquid circulation tank 105 is introduced into the first cathode chamber 151 and the first anode chamber 152, and circulates between the electrode liquid circulation tank 105 and the first cathode chamber 151 and the first anode chamber 152.

[0113] Turn on the external power supply to provide an electric field for the four-compartment electrochemical reactor, causing anions and cations to move directionally within the reactor. During the liquid circulation process described above, considering the combined effects of the electric field, concentration gradient, and the confinement effect of the ion exchange membrane, the main flow direction of substances in each compartment is as follows: Alkali compartment: Na+ migrates out. + and OH -Product chamber: Amin and AminH migrated in. + and OH - Raw material room: Amin and AminH migrated out. + and [HSS] - Recovery liquid chamber: Amin and Na migrate in. + and [HSS] - .

[0114] After continuous operation of the four-chamber electrochemical reaction membrane stack, the alkali solution in the alkali solution chamber 12 becomes dilute; the pure water in the product solution chamber 13 is converted into product solution; the raw materials in the raw material chamber 14 are purified; and the pure water in the recovery solution chamber 11 is converted into recovery solution.

[0115] When the ratio of organic amine concentration in the recovered liquid to organic amine concentration in the raw material reaches C... R-Amin / C O-Amin If the ratio is greater than a certain proportion (exemplarily 0.40), then the second raw material circulation valve 1043 is closed, and the first raw material circulation valve 1041, the raw material circulation pump 1042, and the raw material collection valve 1044 are opened, so that the purified raw material in the raw material circulation tank 104 is drawn out to the collection tank. The second product liquid circulation valve 1033 is closed, and the first product liquid circulation valve 1031, the product liquid circulation pump 1032, and the product liquid collection valve 1034 are opened, so that the product liquid in the product liquid circulation tank 103 is drawn out to the collection tank. Close the first recovered liquid return valve 1013, and open the second recovered liquid return valve 2014, the second recovered liquid circulation valve 2011, the second recovered liquid circulation pump 2012, and the third recovered liquid circulation valve 2013 (i.e., the second state, where the inlet of the recovered liquid chamber 11 is only connected to the outlet of the first recovered liquid circulation tank 101, and the outlet of the recovered liquid chamber 11 is only connected to the inlet of the second recovered liquid circulation tank 201). Close the recovered liquid purification collection valve 2015 to draw recovered liquid from the recovered liquid chamber 11 and introduce it into the second recovered liquid circulation tank 201. Then, the recovered liquid in the second recovered liquid circulation tank 201 is introduced into the recovered liquid purification chamber 21, circulating between the second recovered liquid circulation tank 201 and the recovered liquid purification chamber 21. Open the waste material circulation valve 2021 and the waste material circulation pump 2022 to introduce pure water from the waste material circulation tank 202 into the waste material chamber 22, circulating between the waste material circulation tank 202 and the waste material chamber 22. The electrode liquid outlet valve 1051, electrode liquid circulation pump 1052, second electrode liquid circulation valve 1056, and second electrode liquid return valve 1055 are opened (i.e., the fourth state, the electrode liquid circulation tank 105 is connected to the second cathode chamber 251 and the second anode chamber 252) so that the electrode liquid in the electrode liquid circulation tank 105 is introduced into the second cathode chamber 251 and the second anode chamber 252 and circulates between the electrode liquid circulation tank 105, the second cathode chamber 251, and the second anode chamber 252.

[0116] The second power supply is activated to provide an electric field for the two-compartment electrochemical reaction membrane stack, causing anions and cations to move directionally within the stack. During the aforementioned liquid circulation process, considering the combined effects of the electric field, concentration gradient, and ion exchange membrane confinement, the main material flow directions in each compartment are as follows: Recovery liquid purification compartment: Amin and Na migrate out. + and [HSS] - Waste chamber: Amin and Na are introduced. + and [HSS] - .

[0117] After continuous operation of the two-chamber electrochemical reaction membrane stack, the recovered liquid in the recovered liquid purification chamber 21 is purified and transformed into recovered liquid purified liquid; the pure water in the waste chamber 22 is transformed into waste.

[0118] When the thermally stable salt content of the recovered liquid and purified liquid is less than a certain concentration (exemplarily 5000 ppm), the third recovered liquid circulation valve 2013 is closed, and the recovered liquid and purified liquid collection valve 2015 is opened so that the recovered liquid and purified liquid can be led out to the collection tank.

[0119] It should be noted that the above description is intended only to illustrate the apparatus and method of the present invention in conjunction with the accompanying drawings, and is not intended to limit the present invention.

[0120] Example It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this specification should have the ordinary meaning as understood by one of ordinary skill in the art.

[0121] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. All materials and reagents used in the following examples are commercially available products unless otherwise specified.

[0122] The equipment and materials used in the embodiments are shown below: The electrodialysis system used in the examples and comparative examples includes device CH-0H, device CH-0, and several water tanks. These water tanks can be configured as collection tanks, electrode liquid circulation tanks, product liquid circulation tanks, first recovery liquid circulation tanks, second recovery liquid circulation tanks, alkali liquid circulation tanks, raw material circulation tanks, waste material circulation tanks, etc., as needed.

[0123] Device CH-0H: Manufactured by Hangzhou Jiangrongdao Environmental Technology Co., Ltd., this equipment contains a four-chamber electrochemical reactor consisting of 10 four-chamber repeating units, a cathode plate, an anode plate, a first cathode chamber, and a first anode chamber (see reference). Figure 3 The effective area of ​​a single ion exchange membrane is 0.21 m². 2 .

[0124] Device CH-0: Manufactured by Hangzhou Jiangrongdao Environmental Technology Co., Ltd., this equipment includes a two-chamber electrochemical reactor consisting of 10 two-chamber repeating units, a cathode plate, an anode plate, a second cathode chamber, and a second anode chamber (see reference). Figure 4 The effective area of ​​a single ion exchange membrane is 0.21 m². 2 .

[0125] Anion exchange membrane: Anion exchange membrane (model AMVN) purchased from Asahi Glass, Japan, which includes anion exchange resin and a support mesh made of polyethylene.

[0126] Cation exchange membrane: The cation exchange membrane (model CMVN) was purchased from Asahi Glass, Japan. It consists of cation exchange resin and a support mesh made of ethylene-tetrafluoroethylene copolymer.

[0127] The raw materials contain organic amine compounds and thermally stable salts, wherein the organic amine compounds are hydroxyethyl ethylenediamine and monoethanolamine; the thermally stable salt cations are protonated hydroxyethyl ethylenediamine and monoethanolamine, and the thermally stable salt anions are formate, acetate, glycolate, sulfate, oxalate and chloride ions.

[0128] The content (mass concentration) of each organic amine compound and thermally stable salt in the solution was determined by ion chromatography. The contents of each organic amine compound were added together to obtain the total content of organic amine compounds in the solution. The contents of each thermally stable salt were added together to obtain the content of thermally stable salts in the solution.

[0129] In this invention, the formula for calculating the recovery rate of organic amine compounds in combined electrodialysis is as follows: η = (m) A / m B ) × 100% m A The mass of organic amine compounds in the total amine recovery liquid after the experiment (the liquid in the collection tank, which in the example is the purified raw material + product liquid + recovered liquid purified liquid) can be calculated based on the mass of the total recovery liquid and the mass concentration of organic amine compounds.

[0130] m B The mass of the organic amine compound in the raw material before the experiment can be calculated based on the mass of the raw material and the mass concentration of the organic amine compound.

[0131] In this invention, the formula for calculating the thermally stable salt removal rate of electrodialysis is: σ = (1-m) C / m D ) × 100% m CThe mass of thermally stable salts in the total amine recovery liquid after the experiment (the liquid in the collection tank, which in the example is the purified raw material + product liquid + recovered liquid purified liquid) can be calculated based on the mass of the total recovery liquid and the mass concentration of thermally stable salts.

[0132] m D The mass of the thermally stable salt in the raw material before the experiment can be calculated based on the mass of the raw material and the mass concentration of the thermally stable salt.

[0133] In the mentioned embodiments and comparative examples, the inter-membrane voltage of the four-chamber electrochemical reaction membrane stack is 10V, and the inter-membrane voltage of the two-chamber electrochemical reaction membrane stack is 5V.

[0134] Example 1 use Figure 2 The electrodialysis system described herein, and based on the... Figure 2 The instructions will be followed for implementation.

[0135] Each batch of raw material weighs 5 kg, with an organic amine concentration of 42.3% and a thermally stable salt concentration of 11298 ppm. The alkali tank contains a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 8.4 L.

[0136] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of seven samples. The current density of the four-compartment electrochemical reactor was monitored within the range of 80-150 A / m during the experiment. 2 .

[0137] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.45, the recovered liquid is transferred from the four-chamber electrochemical reaction membrane stack to the two-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 389,140 ppm, and the concentration of organic amine compounds in the recovered liquid is 19.0%.

[0138] When the thermal stability salt content of the recovered purified solution reached 241 ppm, the solution was drained into a collection tank. At this point, the concentration of organic amine compounds in the recovered purified solution was 26.5%. During the experiment, the current density of the two-chamber electrochemical reaction membrane stack was monitored in the range of 150-200 A / m. 2 .

[0139] The current density ratio between the four-chamber electrochemical reactor and the two-chamber electrochemical reactor is (0.40~1.00):1.

[0140] After the above treatment, the mass of the amine liquid (including the purified raw material, product liquid and recovered liquid) collected in the collection tank is 35.5 kg, of which the mass concentration of organic amine is 39.79% and the mass concentration of thermally stable salt is 239.48 ppm.

[0141] Example 2 use Figure 2 The electrodialysis system described herein, and based on the... Figure 2 The instructions will be followed for implementation.

[0142] Each batch of raw material weighs 5 kg, with an organic amine concentration of 44.5% and a thermally stable salt concentration of 14982 ppm. The alkali tank contains a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 17.5 L.

[0143] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of 14 samples. The current density of the four-compartment electrochemical reactor was monitored within the range of 100-350 A / m during the experiment. 2 .

[0144] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.90, the recovered liquid is transferred from the four-chamber electrochemical reaction membrane stack to the two-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 735,129 ppm, and the concentration of organic amine compounds in the recovered liquid is 40.2%.

[0145] When the heat-stable salt content of the purified recovery solution reached 298 ppm, the purified recovery solution was drawn into a collection tank. At this point, the concentration of organic amine compounds in the purified recovery solution was 41.0%. During the experiment, the current density of the electrochemical reaction membrane stack in the two chambers was monitored in the range of 180-250 A / m. 2 .

[0146] The current density ratio between the four-chamber electrochemical reactor and the two-chamber electrochemical reactor is (0.40~1.94):1.

[0147] After the above treatment, the mass of the amine liquid (including the purified raw material, product liquid and recovered liquid) collected in the collection tank is 67 kg, of which the mass concentration of organic amine is 45.84% and the mass concentration of thermally stable salt is 302.88 ppm.

[0148] Example 3 use Figure 2 The electrodialysis system described herein, and based on the... Figure 2 The instructions will be followed for implementation.

[0149] Each batch of raw material weighs 5 kg, with an organic amine concentration of 44.5% and a thermally stable salt concentration of 14982 ppm. The alkali tank contains a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 17.5 L.

[0150] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of 14 samples. The current density of the four-compartment electrochemical reactor was monitored within the range of 100-350 A / m during the experiment. 2 .

[0151] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.42, the recovered liquid is transferred from the four-chamber electrochemical reaction membrane stack to the two-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 613,812 ppm, and the concentration of organic amine compounds in the recovered liquid is 18.7%.

[0152] When the heat-stable salt content of the purified recovery solution reached 1742 ppm, the purified recovery solution was drawn into a collection tank. At this point, the concentration of organic amine compounds in the purified recovery solution was 32.1%. During the experiment, the current density of the electrochemical reaction membrane stack in the two chambers was monitored in the range of 180-250 A / m. 2 .

[0153] The current density ratio between the four-chamber electrochemical reactor and the two-chamber electrochemical reactor is (0.40~1.94):1.

[0154] After the above treatment, the mass of the amine liquid (including the purified raw material, product liquid and recovered liquid) collected in the collection tank is 70 kg, of which the mass concentration of organic amine is 43.61% and the mass concentration of thermally stable salt is 338.22 ppm.

[0155] Example 4 use Figure 2 The electrodialysis system described herein, and based on the... Figure 2 The instructions will be followed for implementation.

[0156] Each batch of raw material weighs 5 kg, with an organic amine concentration of 35.7% and a thermally stable salt concentration of 27,836 ppm. The alkali tank contains a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 17.5 L.

[0157] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of seven samples. The current density of the four-compartment electrochemical reactor was monitored within the range of 150-320 A / m during the experiment.2 .

[0158] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.42, the recovered liquid is transferred from the four-chamber electrochemical reaction membrane stack to the two-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 612024 ppm, and the concentration of organic amine compounds in the recovered liquid is 14.5%.

[0159] When the heat-stable salt content of the purified recovery solution reached 1823 ppm, the purified recovery solution was drawn into a collection tank. At this point, the concentration of organic amine compounds in the purified recovery solution was 41.0%. During the experiment, the current density of the electrochemical reaction membrane stack in the two chambers was monitored in the range of 150-320 A / m. 2 .

[0160] The current density ratio between the four-chamber electrochemical reactor and the two-chamber electrochemical reactor is (0.47~2.13):1.

[0161] After the above treatment, the mass of the amine liquid (including the purified raw material, product liquid and recovered purified liquid) collected in the collection tank is 35.5 kg, of which the mass concentration of organic amine is 34.5% and the mass concentration of thermally stable salt is 1681.63 ppm.

[0162] Comparative Example 1 (Combined Electrodialysis of Two-Compartment + Two-Compartment) Use such as Figure 5 The combined electrodialysis system shown includes a first two-chamber electrochemical reaction membrane stack, a first recovery liquid circulation tank, a raw material circulation tank, a second two-chamber electrochemical reaction membrane stack, a second recovery liquid circulation tank, a waste circulation tank, an electrode liquid circulation tank, a collection tank, and several valves and pumps.

[0163] The internal structure diagrams of the first and second chamber electrochemical reactors and the second and second chamber electrochemical reactors are shown below. Figure 4 As shown, you can refer to Figure 4 The differences are as follows: In the two-chamber repeating unit of the first two-chamber electrochemical reaction membrane stack, 21 represents the feed chamber (hereinafter referred to as 34), 22 represents the recovery liquid chamber (hereinafter referred to as 31), 251 represents the third cathode chamber (hereinafter referred to as 351), and 252 represents the third anode chamber (hereinafter referred to as 352); In the two-chamber repeating unit of the second two-chamber electrochemical reaction membrane stack, 21 represents the recovery liquid purification chamber (hereinafter referred to as 41), 22 represents the waste chamber (hereinafter referred to as 42), 251 represents the fourth cathode chamber (hereinafter referred to as 451), and 252 represents the fourth anode chamber (hereinafter referred to as 452).

[0164] Reference Figure 5 Please provide an explanation.

[0165] Valve 3011, pump 3012, and valve 3013 are opened, and valve 4014 is closed, so that pure water in the first recovery liquid circulation tank 301 is introduced into the recovery liquid chamber 31 and circulates between the first recovery liquid circulation tank 301 and the recovery liquid chamber 31. Valve 3041, pump 3042, and valve 3043 are opened, and valve 3044 is closed, so that raw material in the raw material circulation tank 304 (here the raw material is pre-mixed with alkali solution) is introduced into the raw material chamber 34 and circulates between the raw material circulation tank 304 and the raw material chamber 34. Valve 3051, pump 3052, valve 3053, and valve 3054 are opened, and valves 3055 and valve 3056 are closed, so that the electrode liquid in the electrode liquid circulation tank 305 is introduced into the third cathode chamber 351 and the third anode chamber 352 and circulates between the electrode liquid circulation tank 305 and the third cathode chamber 351 and the third anode chamber 352.

[0166] An electric field is provided to the first and second chamber electrochemical reaction membrane stack, causing anions and cations to move directionally within the stack. When the ratio of the organic amine concentration in the recovered liquid to that in the feed reaches a certain proportion, valve 3013 is closed, and valves 4014, 4011, pump 4012, and valve 4013 are opened, while valve 4015 is closed. This allows the recovered liquid to be drawn from the recovered liquid chamber 31 and introduced into the second recovered liquid circulation tank 401. The recovered liquid in the second recovered liquid circulation tank 401 is then introduced into the recovered liquid purification chamber 41, circulating between the two chambers. Valve 4021 and pump 4022 are opened to allow pure water from the waste circulation tank 402 to be introduced into the waste chamber 42, circulating between the two chambers. Valve 3051, pump 3052, valve 3056, and valve 3055 are opened to allow the electrode liquid in the electrode liquid circulation tank 305 to be introduced into the fourth cathode chamber 451 and the fourth anode chamber 452, and to circulate between the electrode liquid circulation tank 305 and the fourth cathode chamber 451 and the fourth anode chamber 452. Valve 3043 is closed, and valves 3041, pump 3042, and valve 3044 are opened to allow the purified raw material in the raw material circulation tank 304 to be drawn out to the collection tank.

[0167] An electric field is provided for the second-chamber electrochemical reaction membrane stack, causing anions and cations to move directionally within the stack. Through continuous operation of the two-chamber electrochemical reaction membrane stack, the recovered liquid in the recovery liquid purification chamber 41 is purified and converted into a purified recovery liquid; the pure water in the waste chamber 42 is converted into waste.

[0168] When the thermally stable salt content of the recovered liquid and purified liquid is less than a certain concentration, valve 4013 is closed, and valve 4015 is opened so that the recovered liquid and purified liquid can be led out to the collection tank.

[0169] Each batch of raw material weighs 5 kg, with an organic amine concentration of 44.5% and a thermally stable salt concentration of 14982 ppm. The alkali solution is a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 17.5 L. Each batch of raw material is pre-mixed with 1.25 L of a 10 mol / L sodium hydroxide solution.

[0170] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of 14 samples. The current density of the electrochemical reaction membrane stacks in the first and second chambers was monitored to range from 100 to 250 A / m during the experiment. 2 .

[0171] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.87, the recovered liquid is transferred from the first two-chamber electrochemical reaction membrane stack to the second two-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 125,859 ppm, and the concentration of organic amine compounds in the recovered liquid is 38.7%.

[0172] When the heat-stable salt content of the purified recovery solution reached 420 ppm, the purified recovery solution was drawn into a collection tank. At this point, the concentration of organic amine compounds in the purified recovery solution was 41.0%. During the experiment, the current density of the electrochemical reaction membrane stack in the second chamber was monitored to be in the range of 150-250 A / m. 2 .

[0173] After the above treatment, the mass of the amine solution (including the product liquid, the recovered liquid, and the purified liquid) collected in the collection tank is 68 kg, of which the mass concentration of organic amine is 43.51% and the mass concentration of thermally stable salt is 1632.20 ppm.

[0174] Comparative Example 2 (Combined Electrodialysis of Four-Compartment + Four-Compartment) Use such as Figure 6 The combined electrodialysis system shown includes a first four-chamber electrochemical reaction membrane stack, a first recovery liquid circulation tank, a first alkali circulation tank, a first product liquid circulation tank, a raw material circulation tank, a second four-chamber electrochemical reaction membrane stack, a waste circulation tank, a second alkali circulation tank, a second product liquid circulation tank, a second recovery liquid circulation tank, an electrode liquid circulation tank, a collection tank, and several valves and pumps.

[0175] The internal structural diagrams of the first and second chamber electrochemical reactors are shown below. Figure 3 As shown, you can refer to Figure 3 The difference lies in the following: In the four-chamber repeating unit of the first four-chamber electrochemical reaction membrane stack, numeral 11 represents the first recovery liquid chamber (hereinafter referred to as 51), numeral 12 represents the first alkali chamber (hereinafter referred to as 52), numeral 13 represents the first product liquid chamber (hereinafter referred to as 53), numeral 14 represents the feed chamber (hereinafter referred to as 54), numeral 151 represents the fifth cathode chamber (hereinafter referred to as 551), and numeral 152 represents the fifth anode chamber (hereinafter referred to as 551). (Referring to 552); In the four-chamber repeating unit of the second four-chamber electrochemical reaction membrane stack, numeral 11 represents the waste chamber (hereinafter referred to as 61), numeral 12 represents the second alkali chamber (hereinafter referred to as 62), numeral 13 represents the second product chamber (hereinafter referred to as 63), numeral 14 represents the recovery liquid purification chamber (hereinafter referred to as 64), numeral 151 represents the sixth cathode chamber (hereinafter referred to as 651), and numeral 152 represents the sixth anode chamber (hereinafter referred to as 652).

[0176] Reference Figure 6 Please provide an explanation.

[0177] Valve 5011, pump 5012, and valve 5013 are opened, and valve 6045 is closed, so that pure water in the first recovered liquid circulation tank 501 is introduced into the first recovered liquid chamber 51 and circulates between the first recovered liquid circulation tank 501 and the first recovered liquid chamber 51. Valve 5021 and pump 5022 are opened, so that alkali in the first alkali circulation tank 502 is introduced into the first alkali chamber 52 and circulates between the first alkali circulation tank 502 and the first alkali chamber 52. Valve 5031, pump 5032, and valve 5033 are opened, and valve 5034 is closed, so that pure water in the first product liquid circulation tank 503 is introduced into the first product liquid chamber 53 and circulates between the first product liquid circulation tank 503 and the first product liquid chamber 53. Valve 5041, pump 5042, and valve 5043 are opened, and valve 5044 is closed, so that the raw material in the raw material circulation tank 504 is introduced into the raw material chamber 54 and circulates between the raw material circulation tank 504 and the raw material chamber 54. Valve 5051, pump 5052, valve 5053, and valve 5054 are opened, and valves 5055 and valve 5056 are closed, so that the electrode liquid in the electrode liquid circulation tank 505 is introduced into the fifth cathode chamber 551 and the fifth anode chamber 552 and circulates between the electrode liquid circulation tank 505 and the fifth cathode chamber 551 and the fifth anode chamber 552.

[0178] An electric field is provided to the first four-chamber electrochemical reaction membrane stack, causing anions and cations to move directionally within the stack. When the ratio of the organic amine concentration in the recovered liquid to that in the feed reaches a certain proportion, valve 5013 is closed, and valves 6045, 6041, pump 6042, and valve 6043 are opened, while valve 6044 is closed. This allows the recovered liquid to be drawn from the first recovered liquid chamber 51 and introduced into the second recovered liquid circulation tank 604. The recovered liquid in the second recovered liquid circulation tank 604 is then introduced into the recovered liquid purification chamber 64, where it circulates between the two chambers.

[0179] Valve 6011 and pump 6012 are opened to allow pure water from waste circulation tank 601 to be introduced into waste chamber 61, and to circulate between waste circulation tank 601 and waste chamber 61. Valve 6021 and pump 6022 are opened to allow alkali solution from second alkali solution circulation tank 602 to be introduced into second alkali solution chamber 62, and to circulate between second alkali solution circulation tank 602 and second alkali solution chamber 62. Valve 6031, pump 6032, and valve 6033 are opened, and valve 6034 is closed to allow pure water from second product solution circulation tank 603 to be introduced into second product solution chamber 63, and to circulate between second product solution circulation tank 603 and second product solution chamber 63. Valve 5051, pump 5052, valve 5056, and valve 5055 are opened to allow the electrode liquid in the electrode liquid circulation tank 505 to be introduced into the sixth cathode chamber 651 and the sixth anode chamber 652, and to circulate between the electrode liquid circulation tank 505 and the sixth cathode chamber 651 and the sixth anode chamber 652. Valve 5043 is closed, and valves 5041, pump 5042, and valve 5044 are opened to allow the purified raw material in the raw material circulation tank 504 to be drawn out to the collection tank. Valve 5033 is closed, and valves 5031, pump 5032, and valve 5034 are opened to allow the first product liquid in the first product liquid circulation tank 503 to be drawn out to the collection tank.

[0180] An electric field is provided to the second and fourth chamber electrochemical reaction membrane stack, causing anions and cations to move directionally within the stack. Through continuous operation of the four-chamber electrochemical reaction membrane stack, the recovered liquid in the recovery liquid purification chamber 61 is purified and converted into a recovered liquid purified solution; the pure water in the second product liquid circulation tank is converted into the second product liquid; and the pure water in the waste chamber 42 is converted into waste.

[0181] When the thermally stable salt content of the recovered liquid and purified liquid is less than a certain concentration, valve 6043 is closed, and valve 6044 is opened to allow the recovered liquid and purified liquid to be drawn out to the collection tank. Valve 6033 is closed, and valves 6031, 6032, and 6034 are opened to allow the second product liquid in the second product liquid circulation tank 603 to be drawn out to the collection tank.

[0182] Each batch of raw material weighs 5 kg, with an organic amine concentration of 44.5% and a thermally stable salt concentration of 14982 ppm. The alkali tank contains a sodium hydroxide solution with a concentration of 2 mol / L, and a volume of 17 L.

[0183] During the experiment, one sample of raw material was treated with combined electrodialysis each time, for a total of 14 samples. The current density of the electrochemical reaction membrane stack in the first and fourth chambers was monitored to be between 150 and 300 A / m during the experiment. 2 .

[0184] When the ratio of the concentration of organic amines in the recovered liquid to the concentration of organic amines in the raw material is C R-Amin / C O-Amin When the concentration is 0.90, the recovered liquid is transferred from the first four-chamber electrochemical reaction membrane stack to the second four-chamber electrochemical reaction membrane stack. When the recovered liquid is drawn out from the recovered liquid chamber, the concentration of thermally stable salts in the recovered liquid is 681,143 ppm, and the concentration of organic amine compounds in the recovered liquid is 40.2%.

[0185] When the heat-stable salt content of the purified recovery solution reached 321 ppm, the purified recovery solution was drawn into a collection tank. At this point, the concentration of organic amine compounds in the purified recovery solution was 41.0%. During the experiment, the current density of the electrochemical reaction membrane stack in the second and fourth chambers was monitored to be in the range of 180-400 A / m. 2 .

[0186] After the above treatment, the mass of the amine solution collected in the collection tank (including the purified raw material, the first product liquid, the second product liquid, and the purified recovery liquid) is 66 kg, of which the mass concentration of organic amine is 42.82% and the mass concentration of thermally stable salt is 1220.67 ppm.

[0187] The parameters and their effects in the examples and comparative examples are summarized in Table 1 below: Table 1: Parameters and Effect Data of Examples and Comparative Examples C O-HSS : Initial concentration of thermally stable salts in the raw material, expressed in ppm.

[0188] C O-Amin : Initial concentration of organic amine compounds in the raw material, expressed as a percentage by weight.

[0189] C R-HSS : The concentration of thermally stable salts in the recovered liquid when it is drawn from the recovered liquid chamber, expressed in ppm.

[0190] C R-Amin : The concentration of organic amine compounds in the recovered liquid when it is drawn from the recovered liquid chamber, expressed as a percentage by weight.

[0191] C P-HSS The concentration of thermally stable salts in the recovered liquid and purified liquid when the recovered liquid and purified liquid are drawn from the recovered liquid and purified liquid chamber, expressed in ppm.

[0192] C P-Amin When the recovered liquid is drawn from the purified liquid chamber, the concentration of organic amine compounds in the recovered liquid is expressed as a percentage by weight (%).

[0193] C S-HSS : The concentration of thermally stable salts in the amine solution collected in the collection tank, expressed in ppm.

[0194] C S-Amin : The concentration of organic amine compounds in the amine solution collected in the collection tank, expressed as a percentage by weight.

[0195] σ HSS : The overall thermal stability of the combined electrodialysis system and the salt removal rate, expressed as a percentage.

[0196] η Amin Total recovery rate of organic amine compounds in the combined electrodialysis system, expressed as a percentage.

[0197] While various preferred embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. An electrodialysis method for recovering amines, characterized in that, Includes the following steps: i) Provide a four-chamber electrochemical reaction membrane stack, including a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, the four-chamber repeating unit including an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, each chamber including an inlet and an outlet; ii) Provide a two-chamber electrochemical reaction membrane stack, including a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit includes a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; iii) In the four-chamber electrochemical reaction membrane stack, alkaline solution is introduced into the alkaline solution chamber, pure water is introduced into the product liquid chamber and the recovery liquid chamber, and raw materials are introduced into the raw material chamber so that pure water is converted into recovery liquid in the recovery liquid chamber; iv) Draw the recovered liquid out of the recovery liquid chamber; v) In the two-chamber electrochemical reaction membrane stack, the recovered liquid is introduced into the recovered liquid purification chamber and pure water is introduced into the waste chamber, so that the recovered liquid is converted into the recovered liquid purified liquid in the recovered liquid purification chamber; vi) Draw out the purified liquid from the purified liquid purification chamber; The raw materials contain organic amine compounds and thermally stable salts, and the recovered liquid contains anions of organic amine compounds and thermally stable salts.

2. The method according to claim 1, characterized in that, The method further includes introducing an electrode liquid into a first cathode chamber and / or a first anode chamber and / or a second cathode chamber and / or a second anode chamber.

3. The method according to claim 1 or 2, characterized in that, In the four-chamber electrochemical reaction membrane stack, the first cathode chamber and / or the first anode chamber are adjacent to the alkali chamber via a cation membrane.

4. The method according to claim 1 or 2, characterized in that, In the two-chamber electrochemical reaction membrane stack, the second cathode chamber and / or the second anode chamber are adjacent to the waste chamber via a cation membrane.

5. The method according to claim 2, characterized in that, The polar solution and the alkaline solution are of the same type.

6. The method according to claim 1 or 2, characterized in that, The method includes: The current density range of the four-compartment electrochemical reactor is 50-450 A / m. 2 ; The current density range of the two-compartment electrochemical reactor is 100-400 A / m. 2 ; The current density ratio between the four-compartment electrochemical reactor and the two-compartment electrochemical reactor is (0.3~2.3):

1.

7. The method according to claim 6, characterized in that, The method includes: The current density range of the four-compartment electrochemical reactor is 90-380 A / m. 2 ; The current density range of the two-compartment electrochemical reactor is 160-280 A / m. 2 ; The current density ratio between the four-compartment electrochemical reactor and the two-compartment electrochemical reactor is (0.4~2.0):

1.

8. An electrodialysis system for amine recovery, characterized in that, The electrodialysis system includes: a) A four-chamber electrochemical reaction membrane stack, comprising a first cathode chamber, a first anode chamber, and at least one four-chamber repeating unit disposed therebetween, wherein the four-chamber repeating unit comprises an alkali chamber, a product chamber, a feed chamber, and a recovery chamber arranged sequentially from the first cathode chamber to the first anode chamber, and from the side of the alkali chamber adjacent to the first cathode chamber to the side of the recovery chamber adjacent to the first anode chamber, the four-chamber repeating unit has a cation membrane, an anion membrane, a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; b) A two-chamber electrochemical reaction membrane stack, comprising a second cathode chamber, a second anode chamber, and at least one two-chamber repeating unit disposed therebetween, wherein the two-chamber repeating unit comprises a recovery liquid purification chamber and a waste chamber arranged sequentially from the second cathode chamber to the second anode chamber, and from the side of the recovery liquid purification chamber adjacent to the second cathode chamber to the side of the waste chamber adjacent to the second anode chamber, the two-chamber repeating unit has a cation membrane, an anion membrane, and a cation membrane, and each chamber includes an inlet and an outlet; The recovery liquid chamber of the four-chamber repeating unit is connected to the recovery liquid purification chamber of the two-chamber repeating unit.

9. The electrodialysis system according to claim 8, characterized in that, The system also includes an polar liquid circulation tank, which has an inlet and an outlet. The outlet of the electrode liquid circulation tank is connected to the inlet of the first cathode chamber and / or the inlet of the first anode chamber via a first electrode liquid circulation valve, and is connected to the inlet of the second cathode chamber and / or the inlet of the second anode chamber via a second electrode liquid circulation valve; The outlet of the first cathode chamber and / or the outlet of the first anode chamber are connected to the inlet of the electrode liquid circulation tank via the first electrode liquid reflux valve, and the outlet of the second cathode chamber and / or the outlet of the second anode chamber are connected to the inlet of the electrode liquid circulation tank via the second electrode liquid reflux valve. The electrodialysis system includes a third state and a fourth state that can be switched between each other. In the third state, the electrolytic circulation tank is only connected to the first cathode chamber and / or the first anode chamber. In the fourth state, the electrolytic circulation tank is connected to the first cathode chamber and / or the first anode chamber as well as the second cathode chamber and / or the second anode chamber.

10. The electrodialysis system according to claim 8 or 9, characterized in that, In the four-chamber electrochemical reaction membrane stack, the first cathode chamber and / or the first anode chamber are adjacent to the alkali chamber via a cation membrane.

11. The electrodialysis system according to claim 8 or 9, characterized in that, In the two-chamber electrochemical reaction membrane stack, the second cathode chamber and / or the second anode chamber are adjacent to the waste chamber via a cation membrane.

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