A method for separating organic salts by a donnan dialysis coupled with membrane distillation process

Abstract

The application discloses a method for separating organic salt by Donnan dialysis coupled with membrane distillation process, which comprises the following steps: placing acid wastewater and electrocatalytic synthesis liquid on both sides of a cation exchange membrane in Donnan dialysis, wherein the electrocatalytic synthesis liquid is an alkaline organic aqueous solution; separating a first side chamber and a second side chamber by using a hydrophobic membrane in a membrane distillation process, wherein the solution in the first side chamber is a KOH solution, and the solution in the second side chamber is the electrocatalytic synthesis liquid, and the electrocatalytic synthesis liquid is circulated in the membrane distillation process and the Donnan dialysis; and using a KOH solution as an electrolyte in electrolytic water, and circulating the KOH solution in the first side chamber and the electrolytic water. The method realizes synchronous solution of organic salt dealkalization and acid wastewater neutralization, and reduces the crystallization separation step in the traditional process.

Description

Technical Field

[0001] This invention relates to the field of organic salt separation technology, and more particularly to a method for separating organic salts using a Donnan dialysis coupled membrane distillation process. Background Technology

[0002] Electrocatalytic synthesis of organic compounds often requires the addition of a large amount of electrolytes, the main electrolytes being KOH, NaOH, KHCO3, NaHCO3, K2CO3, Na2CO3, etc., which need to be neutralized by adding acidic substances such as HNO3 and H2SO4. Then, the organic salts and inorganic salts are separated through a crystallization process, and the organic compounds are concentrated through a traditional distillation process.

[0003] Pickling processes generate large amounts of acidic wastewater, 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 to neutralize the wastewater. In addition, acid recovery is also carried out through diffusion dialysis, electrodialysis, and other methods to improve acid utilization.

[0004] However, adding acidic substances for neutralization requires additional separation and crystallization processes of inorganic and organic salts, and the lower the concentration of organic matter, 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 utilization value of the acid. Furthermore, methods such as diffusion dialysis and electrodialysis often require the addition of large amounts of water, further increasing energy consumption and costs.

[0005] Therefore, there is an urgent need for a method to separate organic salts using the Donnan dialysis-coupled membrane distillation process, which 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, this invention provides a method for separating organic salts using a Donnan dialysis coupled membrane distillation process. The technical solution adopted by this invention to solve the above problems is: a method for separating organic salts using a Donnan dialysis coupled membrane distillation process, the method 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 the membrane distillation process, a hydrophobic membrane is used to separate a first side chamber and a second side chamber. The solution in the first side chamber is a KOH solution, and the solution in the second side chamber is the electrocatalytic synthesis solution. The electrocatalytic synthesis solution is circulated in the membrane distillation process and the Donnan dialysis.

[0008] KOH solution is used as the electrolyte in the electrolysis of water, and the KOH solution circulates in the first side chamber and the electrolyzed 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, the 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 effects achieved by this invention are: realizing the recycling of solutions in water electrolysis, membrane distillation, and Donnan dialysis. Specifically, the Donnan dialysis process removes a large amount of alkali from the organic salt solution (electrocatalytic synthesis solution) and neutralizes the acid in the acidic wastewater, reducing the complexity of the organic matter separation process and simplifying the process route. Furthermore, the removal of alkali from the organic aqueous solution (electrocatalytic synthesis solution) improves the mass transfer performance of membrane distillation. Additionally, driving the membrane distillation process with water electrolysis achieves solution concentration, reducing the large amount of energy required in traditional distillation processes and avoiding the additional energy consumption required for KOH solution regeneration, thus achieving energy conservation and environmental protection. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating an implementation of the present invention. Detailed Implementation

[0014] To make the above-mentioned objects, features, and advantages of the present invention more readily understood, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0015] This invention discloses a method for separating organic salts using a Donnan dialysis-coupled membrane distillation process. This method is applied to the concentration of electrocatalytic synthesis solutions and the neutralization treatment of industrial waste acids, such as... Figure 1 As shown, in the Donnan dialysis process, acidic wastewater and electrocatalytic synthesis solution are placed on both sides of a cation exchange membrane, wherein the electrocatalytic synthesis solution is an alkaline organic aqueous solution;

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

[0017] KOH solution is used as the electrolyte in water electrolysis. The KOH solution circulates in the first side chamber and the water being electrolyzed, thereby maintaining the stability of the KOH solution concentration 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 used as the driving force for concentration. The KOH solution is a 5-37 wt% KOH solution. Preferably, the KOH solution is a 23 wt% KOH solution.

[0019] It should be noted that the combination of the membrane distillation process and the electrolysis of water can be found in: Application No. 202510556816.0, A method for enhancing mass transfer by driving double-sided gas-blowing membrane distillation with electrolysis of water.

[0020] Specifically, in the electrolysis of water, an alkaline solution (KOH solution) is used as the electrolyte for 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] Mass transfer of water molecules is achieved by using vapor pressure difference to drive liquid water molecules in the second side chamber. The liquid water molecules absorb heat, vaporize, and pass through the hydrophobic membrane into the first side chamber, where they condense into liquid.

[0022] Homogenization utilizes the hydrogen gas generated in the cathode chamber during water electrolysis to homogenize the electrolyte concentration within the cathode chamber.

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

[0024] During the Donnan dialysis process, the concentration difference drives the diffusion and migration of H+ and K+ in the solution, thereby obtaining an alkali-free organic aqueous solution and an acidic wastewater solution with a high pH value that meets discharge standards. The acidic wastewater is treated using a cation exchange membrane, ultimately achieving the synergistic effect of the Donnan dialysis, the membrane distillation process, and the water electrolysis to achieve the purpose of this application: to simultaneously solve the problems of organic salt dealkalization and acidic wastewater neutralization, and to reduce the crystallization and separation steps in traditional processes.

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

[0026] In summary, this application achieves solution recycling in water electrolysis, membrane distillation, and Donnan dialysis. The Donnan dialysis process removes a large amount of alkali from the organic salt solution (electrocatalytic synthesis solution) and neutralizes the acid in the acidic wastewater, reducing the complexity of the organic matter separation process and simplifying the process route. Furthermore, the removal of alkali from the organic aqueous solution (electrocatalytic synthesis solution) improves the mass transfer performance of the membrane distillation. Additionally, the water electrolysis-driven membrane distillation process achieves solution concentration, reducing the large amount of energy required in traditional distillation processes and avoiding the additional energy consumption required for KOH solution regeneration, thus achieving energy conservation and environmental protection.

[0027] The embodiments described above are merely illustrative of one or more implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

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

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

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

4. The method for separating organic salts using the 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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