Method for separating organic salt by Donnan dialysis coupling membrane distillation process

Abstract

The invention discloses a method for separating organic salt by a Donnan dialysis coupling membrane distillation process, which comprises the following steps: in Donnan dialysis, acid wastewater and electrocatalytic synthesis liquid are placed on two sides of a cation exchange membrane, and the electrocatalytic synthesis liquid is an alkali-containing organic water solution; in the membrane distillation process, a hydrophobic membrane is used for separating a first side chamber from a second side chamber, a solution in the first side chamber is a KOH solution, a solution in the second side chamber is the electro-catalytic synthesis liquid, and the electro-catalytic synthesis liquid circulates in the membrane distillation process and the Donnan dialysis; a KOH solution is used as an electrolyte in the electrolyzed water, and the KOH solution circulates in the first side chamber and the electrolyzed water. Organic salt dealkalization and acid wastewater neutralization are synchronously solved, and the crystallization separation step in the traditional process is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of organic salt separation, in particular to a method for separating organic salts using a Donnan dialysis-coupled membrane distillation process. Background Art

[0002] The electrocatalytic synthesis of organic compounds often requires the addition of a large amount of electrolytes, among which the main electrolytes are KOH, NaOH, KHCO3, NaHCO3, K2CO3, Na2CO3, etc. Acidic substances such as HNO3 and H2SO4 need to be added for neutralization, and then the organic salts and inorganic salts are separated through a crystallization process, and then the organic matter is concentrated through a traditional distillation process.

[0003] A large amount of acidic wastewater is produced in the pickling industry, which often contains metal ions of different valence states, such as Fe 3+ , Cu 2+ Such wastewater often needs to be treated before it can be discharged. The main method is neutralization, which involves adding a large amount of alkaline substances for neutralization. In addition, acid recovery is also carried out through diffusion dialysis, electrodialysis, etc. to improve acid utilization.

[0004] However, neutralization with acidic substances requires the additional separation and crystallization of inorganic and organic salts, and the lower the organic concentration, the higher the energy consumption for distillation and concentration. Existing industrial acidic wastewater often requires the addition of large amounts of alkaline substances for neutralization before discharge, resulting in high alkali consumption and reduced acid utilization. Diffusion dialysis and electrodialysis methods often require the addition of large amounts of water, increasing energy consumption and costs.

[0005] Therefore, there is an urgent need for a method for separating organic salts by using a Donnan dialysis-coupled membrane distillation process that can solve one or more of the above problems. Summary of the Invention

[0006] To address one or more problems existing in the prior art, the present invention provides a method for separating organic salts using a Donnan dialysis-coupled membrane distillation process. The present invention employs a technical solution to address the aforementioned problems, comprising: placing acidic wastewater and an electrocatalytic synthesis solution on opposite sides of a cation exchange membrane in a Donnan dialysis process, wherein the electrocatalytic synthesis solution is an alkaline organic aqueous solution;

[0007] In a membrane distillation process, a hydrophobic membrane is used to separate a first side chamber from a second side chamber, the solution in the first side chamber is a KOH solution, the solution in the second side chamber is the electrocatalytic synthesis solution, and the electrocatalytic synthesis solution circulates in the membrane distillation process and the Donnan dialysis;

[0008] A KOH solution is used as an electrolyte in the electrolysis of water, and the KOH solution circulates in the first side chamber and the electrolysis water.

[0009] In some embodiments, the hydrophobic membrane is any one or more combinations of polytetrafluoroethylene membrane, polyvinylidene fluoride membrane, and polypropylene membrane.

[0010] In some embodiments, vapor pressure difference is used as the driving force for concentration in the membrane distillation process.

[0011] In some embodiments, the KOH solution is a 5-37 wt % KOH solution.

[0012] The technical effect achieved by the present invention is: realizing the recycling of solutions in electrolysis of water, membrane distillation process and Donnan dialysis, wherein a large amount of alkali contained in the organic salt solution (electrocatalytic synthesis liquid) is removed through the Donnan dialysis process, and the acid in the acidic wastewater is neutralized, thereby reducing the complexity of the organic matter separation process and simplifying the process route. In addition, due to the removal of alkali in the organic aqueous solution (electrocatalytic synthesis liquid), the mass transfer performance of membrane distillation is improved, and the membrane distillation process is driven by electrolysis of water to achieve solution concentration, thereby reducing the large amount of energy required for the traditional distillation process and avoiding the additional energy consumption required for the regeneration of the KOH solution, thereby achieving the purpose of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram for the implementation of the present invention. DETAILED DESCRIPTION

[0014] To make the above-mentioned objects, features, and advantages of the present invention more readily understood, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0015] The present invention discloses a method for separating organic salts by Donnan dialysis coupled with membrane distillation process, which is applicable to the concentration of electrocatalytic synthesis liquid and the neutralization treatment of industrial waste acid. Figure 1 As shown, in Donnan dialysis, acidic wastewater and electrocatalytic synthesis liquid are placed on both sides of a cation exchange membrane, and the electrocatalytic synthesis liquid is an alkaline organic aqueous solution;

[0016] In a membrane distillation process, a hydrophobic membrane is used to separate a first side chamber from a second side chamber, the solution in the first side chamber is a KOH solution, the solution in the second side chamber is the electrocatalytic synthesis solution, and the electrocatalytic synthesis solution circulates in the membrane distillation process and the Donnan dialysis;

[0017] A KOH solution is used as an electrolyte in the electrolysis of water, and the KOH solution circulates in the first side chamber and the electrolysis water, thereby maintaining a stable concentration of the KOH solution in the membrane distillation process.

[0018] It should be noted that the hydrophobic membrane is any one or more combinations of polytetrafluoroethylene membrane, polyvinylidene fluoride membrane, and polypropylene membrane. Preferably, the hydrophobic membrane is a porous hydrophobic and breathable polytetrafluoroethylene membrane; in the membrane distillation process, the vapor pressure difference is the driving force for concentration; the KOH solution is a 5-37wt% KOH solution, preferably, the KOH solution is a 23wt% KOH solution.

[0019] It should be noted that for the combination of the membrane distillation process and the electrolysis of water, reference may be made to: Application No. 202510556816.0, a method for enhancing mass transfer by electrolysis-driven double-sided aerated membrane distillation.

[0020] Specifically, in the electrolysis of water, an alkaline solution (KOH solution) is used as the electrolyte in the anode chamber and the cathode chamber, the anode chamber and the cathode chamber are separated by a nylon diaphragm, the anode material is NiCo alloy, and the cathode material is NiMo alloy;

[0021] Water molecule mass transfer, using vapor pressure difference to drive liquid water molecules in the second side chamber, the liquid water molecules absorb heat and vaporize and pass through the hydrophobic membrane into the first side chamber to condense into liquid;

[0022] Homogenization, using the hydrogen generated in the cathode chamber during water electrolysis to cause the electrolyte concentration in the cathode chamber to be homogenized;

[0023] During the blowing operation, the oxygen generated by the anode is blown into the second side chamber after gas-liquid separation.

[0024] During the Donnan dialysis process, H+ and K+ in the concentration-driven solution diffuse and migrate, thereby obtaining an alkali-free organic aqueous solution and an acidic wastewater solution with a high pH value that can meet the emission standards. The acidic wastewater is treated with a cation exchange membrane, and ultimately the Donnan dialysis, the membrane distillation process and the electrolysis of water are coordinated to achieve the purpose of this application: to simultaneously solve the dealkalization of organic salts and the neutralization of acidic wastewater, and reduce the crystallization separation steps in the traditional process.

[0025] In the membrane distillation process, the vapor pressure difference on both sides of the hydrophobic membrane is used as the driving force to achieve the concentration of the organic aqueous solution (the electrocatalytic synthesis solution), avoiding the additional absorbent (KOH solution) regeneration process and reducing the concentration energy consumption.

[0026] In summary, the present application realizes the recycling of solutions in water electrolysis, membrane distillation process and Donnan dialysis, wherein a large amount of alkali contained in the organic salt solution (electrocatalytic synthesis liquid) is removed through the Donnan dialysis process, and the acid in the acidic wastewater is neutralized, thereby reducing the complexity of the organic separation process and simplifying the process route. In addition, due to the removal of alkali in the organic aqueous solution (electrocatalytic synthesis liquid), the mass transfer performance of membrane distillation is improved, and the membrane distillation process is driven by water electrolysis to achieve solution concentration, reducing the large amount of energy required in the traditional distillation process, and also avoiding the additional energy consumption required for KOH solution regeneration, thereby achieving the purpose of energy saving and environmental protection.

[0027] The embodiments described above merely represent one or more embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for separating organic salts by using a Donnan dialysis-coupled membrane distillation process, characterized in that: In Donnan dialysis, acidic wastewater and electrocatalytic synthesis liquid are placed on both sides of a cation exchange membrane, wherein the electrocatalytic synthesis liquid is an alkaline organic aqueous solution; In a membrane distillation process, a hydrophobic membrane is used to separate a first side chamber from a second side chamber, the solution in the first side chamber is a KOH solution, the solution in the second side chamber is the electrocatalytic synthesis solution, and the electrocatalytic synthesis solution circulates in the membrane distillation process and the Donnan dialysis; A KOH solution is used as an electrolyte in the electrolysis of water, and the KOH solution circulates in the first side chamber and the electrolysis water.

2. The method for separating organic salts by Donnan dialysis-coupled membrane distillation process according to claim 1, characterized in that: The hydrophobic membrane is any one or more combinations of polytetrafluoroethylene membrane, polyvinylidene fluoride membrane and polypropylene membrane.

3. The method for separating organic salts by Donnan dialysis-coupled membrane distillation process according to claim 1, characterized in that: In the membrane distillation process, vapor pressure difference is used as the driving force for concentration.

4. The method for separating organic salts by Donnan dialysis-coupled membrane distillation process according to claim 1, characterized in that: The KOH solution is a 5-37 wt % KOH solution.

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