CN107285534A - A kind of process for handling the organic wastewater containing free acid and quaternary ammonium salt - Google Patents

Abstract

The invention describes a process for treating organic waste water containing free acid and quaternary ammonium salt. The method treats the organic waste water containing free acid and quaternary ammonium salt by introducing a combination process of diffusion dialysis-electrodialysis-bipolar membrane electrodialysis. First, more than 80% of the free acid in the wastewater is recovered by diffusion dialysis, and then the remaining free acid in the wastewater is recovered by electrodialysis, and finally the quaternary ammonium salt contained in the wastewater is converted into The corresponding conjugate acid of quaternary ammonium base and quaternary ammonium salt anion. After the waste water is treated by the above combined process, the residual concentration of free acid and quaternary ammonium salt can be reduced to below 0.001mol/L, which meets the salt content requirement of biochemical sludge degradation organic matter. The process method treats organic wastewater containing free acid and quaternary ammonium salt without adding other chemicals, and is clean and pollution-free. The purity of the recovered quaternary ammonium alkali solution and conjugate acid solution can reach about 98%~99%, and the whole process Low energy consumption, suitable for industrial production.

Description

A process for treating organic wastewater containing free acid and quaternary ammonium salt

technical field

The invention relates to diffusion dialysis, electrodialysis and bipolar membrane electrodialysis technology, and belongs to the field of electrochemistry and membrane separation. Specifically, it relates to a method for ion separation by electrochemical technology and membrane separation technology.

Background technique

The treatment of organic wastewater containing acid and salt has always been a problem worthy of consideration and research. From the perspective of environmental benefits, it is a process technology with green chemical significance. From the perspective of economic benefits, it is an effective measure that can improve resource utilization.

In the CN104192971A patent, a method for treating industrial wastewater containing sulfuric acid is mentioned, adding calcium hydroxide to industrial wastewater containing sulfuric acid, stirring at room temperature to obtain calcium sulfate, reacting calcium sulfate with ammonium bicarbonate to obtain calcium carbonate, reclaiming ammonium sulfate, and then Calcium carbonate is decomposed to calcium oxide. This method can be used to recover SO ₄ ^2- in wastewater, but the mixing of Ca ²⁺ and other impurity ions is not conducive to the subsequent recovery of quaternary ammonium salts in wastewater.

The method adopted in the CN100999353 patent is to directly add cheaper calcium oxide to sulfuric acid wastewater, but the reaction between calcium oxide and wastewater will release a large amount of heat. In order to prevent calcium oxide from accumulating in the reactor and keep the temperature of the reactor at Below 40°C, the feeding must be uniform and slow, which greatly prolongs the treatment time, and there are also cases of mixed impurity ions, which is not suitable for the recovery of quaternary ammonium salts in subsequent wastewater.

Compared with the traditional chemical method for treating sulfuric acid wastewater, the ionic membrane treatment method has the advantages of simple experimental operation, no pollution, and high purity. CN101045568 patent introduces a method for recovering sulfuric acid in wastewater by using an ionic membrane combination method. Diffusion dialysis-bipolar membrane electrodialysis combined process is adopted, in which the acid recovery rate in the diffusion dialysis process can reach 80%, and the remaining acid is recovered again by bipolar membrane electrodialysis process, which reduces energy consumption. Since this scheme only needs to recover sulfuric acid, the membrane stack configuration of the bipolar membrane adopts the structure of BP-A, which further reduces the membrane stack voltage of the bipolar membrane electrodialysis, thus saving energy consumption.

This technology treats free acid and quaternary ammonium salt in organic wastewater, recovers free acid and quaternary ammonium salt in wastewater through diffusion dialysis-electrodialysis and bipolar membrane electrodialysis combination technology, and uses quaternary ammonium salt to produce quaternary ammonium base has great practical significance. Quaternary ammonium bases can be used as basic organic chemical agents, cleaning reagents in the electronics industry, phase transfer catalysts for alkylation, alkylation, and deprotonation reactions, and can also be used as ion-pair mobile phases in chromatographic techniques. application value.

Contents of the invention

The purpose of the invention is to provide a method for treating organic wastewater containing free acids and quaternary ammonium salts, to recycle the free acids and quaternary ammonium salts in the wastewater, and to improve resource utilization. Using this process method can not only save energy consumption , reduce the cost of wastewater treatment, and can obtain high recovery and high purity products.

The present invention adopts a combination process of diffusion dialysis-electrodialysis-bipolar membrane electrodialysis. Directly adopting the bipolar membrane electrodialysis process consumes a lot of energy, because the wastewater contains free acid, and the hydrogen ions in the wastewater will migrate to the alkali chamber under the action of the electric field force during the process of bipolar membrane electrodialysis to recover quaternary ammonium salts. The hydroxide ions produced by the bipolar membrane are neutralized in the alkali chamber. Therefore, in the case of free acid in the wastewater, the bipolar membrane electrodialysis only plays the role of removing acid, and cannot generate quaternary ammonium base. The acid process consumes a lot of energy and has no practical application value. Therefore, it is necessary to remove a large amount of free acid in wastewater before bipolar membrane electrodialysis.

Diffusion dialysis has the characteristics of simple operation, low energy consumption, and high purity of recovered sulfuric acid. Under certain conditions, the recovery rate of free acid is about 70-85%. The lower the wastewater flow rate during the diffusion dialysis process, the lower the acid concentration in the treated wastewater, which is more conducive to reducing the energy consumption of the bipolar membrane electrodialysis process. However, if the flow rate is too small, the treatment time of diffusion dialysis will be greatly prolonged, or a larger effective area of the ion membrane will be required, which will greatly increase the investment in equipment.

In order to reduce costs, the treatment flow rate of diffusion dialysis can be increased to obtain low-acid wastewater, and the remaining low-concentration acid in the wastewater can be deeply removed by electrodialysis. After the electrodialysis treatment, the wastewater containing almost no free acid can be obtained. Finally, the quaternary ammonium salt in the wastewater can be converted into high-purity conjugate acid and quaternary ammonium base through the bipolar membrane electrodialysis process, and the organic matter can pass through the barrier of anion and cation membranes. The effect remains in the wastewater. Through the comparison of energy consumption, it is found that the combination process of diffusion dialysis-electrodialysis-bipolar membrane electrodialysis needs the least energy consumption, so it is an ideal solution for industrial treatment.

Description of drawings

Figure 1: Flow chart of diffusion dialysis experiment;

Figure 2: Schematic diagram of the electrodialysis experimental device;

Figure 3: Schematic diagram of the experimental setup for bipolar membrane electrodialysis.

detailed description

The present invention will be further described below in conjunction with the examples, but the present invention is not limited to these examples.

Example 1

The wastewater containing 180g/L of H ₂ SO ₄ , 80g/L of DMSO and 40g/L of TBAHSO ₄ is first subjected to diffusion dialysis. The diffusion dialysis device adopts DSV anion exchange membrane, and the flow rate of wastewater is 0.2065 L/h. After 9.7 hours, 2L of low-acid raw material with H ⁺ concentration of 1.056mol/L was obtained, and the acid recovery rate in this process was 72.1%; the low-acid raw material was subjected to electrodialysis treatment, and the electrodialysis device used AMV anion exchange membrane and CSO cation exchange membrane , with a current density of 165 A/m ² , electrodialysis for 3 h, the concentration of H ⁺ in the raw material was reduced to 0.021 mol/L, the mobility of SO ₄ ^2- was 85.4%, and the energy consumption of this process was 0.102 kW·h; The bipolar membrane electrodialysis treatment is carried out. The bipolar membrane electrodialysis device adopts BP-1 bipolar membrane, AMX anion exchange membrane and JCM cation exchange membrane. The initial current density is 150 A/m ² . chamber and alkali chamber respectively generate 0.135 mol/L sulfuric acid solution and 0.108 mol/L tetrabutylammonium hydroxide solution, the energy consumption of this process is 0.223 kW h, and the total energy consumption of the whole combined process is 0.325 kW h, The recovery rate of the finally obtained tetrabutylammonium hydroxide solution was 81.6%, and the purity reached 97.81%.

Comparative Example 1

The existing 2L low-acid raw material with a H ⁺ concentration of 0.917mol/L obtained after diffusion dialysis treatment is directly subjected to bipolar membrane electrodialysis treatment. The bipolar membrane electrodialysis device adopts BP-1 bipolar membrane and AMX anion Exchange membrane and JCM cation exchange membrane, with an initial current density of 150 A/m ² , electrodialysis for 8.5 h, finally generating 0.535 mol/L sulfuric acid solution and 0.130 mol/L tetrabutylammonium hydroxide solution in the acid chamber and alkali chamber respectively , the total energy consumption of the process is 0.786 kW·h, and the recovery rate of the final tetrabutylammonium hydroxide solution is >99%.

Example 2

The wastewater containing 180g/L of H ₂ SO ₄ , 80g/L of DMSO and 40g/L of TBAHSO ₄ is first subjected to diffusion dialysis. The diffusion dialysis device adopts DSV anion exchange membrane, and the flow rate of wastewater is 0.1641 L/h. After 12.2 hours, 2L of low-acid raw material with H ⁺ concentration of 0.979 mol/L was obtained, and the acid recovery rate in this process was 77.1%. The low-acid raw material was subjected to electrodialysis treatment, and the electrodialysis device used AMV anion exchange membrane and CSO cation exchange membrane , the current density was 165 A/m ² , electrodialysis was performed for 3 h, the H ⁺ concentration in the raw material was reduced to 0.023 mol/L, the SO ₄ ^2- mobility was 86.5%, and the energy consumption of this process was 0.099 kW·h; the raw material The bipolar membrane electrodialysis treatment is carried out. The bipolar membrane electrodialysis device adopts BP-1 bipolar membrane, AMX anion exchange membrane and JCM cation exchange membrane. The initial current density is 150 A/m ² . chamber and alkali chamber respectively generate 0.115 mol/L sulfuric acid solution and 0.089 mol/L tetrabutylammonium hydroxide solution, the energy consumption of this process is 0.206 kW h, and the total energy consumption of the whole combined process is 0.305 kW h, The recovery rate of the finally obtained tetrabutylammonium hydroxide solution was 82.3%, and the purity reached 98.13%.

Example 3

The wastewater containing 180g/L of H ₂ SO ₄ , 80g/L of DMSO and 40g/L of TBAHSO ₄ is first subjected to diffusion dialysis. The diffusion dialysis device adopts DSV anion exchange membrane, and the flow rate of wastewater is 0.1217 L/h. After 16.4 hours, 2L of low-acid raw material with H ⁺ concentration of 0.785 mol/L was obtained, and the acid recovery rate in this process was 75.6%; the low-acid raw material was subjected to electrodialysis treatment, and the electrodialysis device used AMV anion exchange membrane and CSO cation exchange membrane , the current density is 165 A/m ² , electrodialysis for 2 h, the concentration of H ⁺ in the raw material is reduced to 0.038 mol/L, the mobility of SO ₄ ^2- is 75.8%, and the energy consumption of this process is 0.089 kW·h; The bipolar membrane electrodialysis treatment is carried out. The bipolar membrane electrodialysis device adopts BP-1 bipolar membrane, AMX anion exchange membrane and JCM cation exchange membrane. The initial current density is 150 A/m ² . chamber and alkali chamber respectively generate 0.169 mol/L sulfuric acid solution and 0.121 mol/L tetrabutylammonium hydroxide solution, the energy consumption of this process is 0.250 kW h, then the total energy consumption of the whole combined process is 0.339 kW h, The recovery rate of the finally obtained tetrabutylammonium hydroxide solution was 92.5%, and the purity reached 97.98%.

Claims (8)

1. a kind of process for handling the organic wastewater containing free acid and quaternary ammonium salt, it is characterised in that described process Carry out according to the following steps：

（1）Waste water raw material is first subjected to diffusion dialysis processing under certain flow and reclaims wherein substantial amounts of free acid, makes waste water former Material becomes the waste water of low concentration acid, the waste water of low concentration acid is carried out after electrodialysis process under certain current density, waste water In be practically free of free acid；

（2）Waste water after electrodialysis process is subjected to bipolar membrane electrodialysis processing under certain current density, respectively in sour room and Alkali room is obtained contained organic matter in the conjugation acid solution and quaternary ammonium alkali solution of high-purity, waste water and retained due to the barriering effect of film In waste water.

2. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Free acid in described waste water can be sulfuric acid, hydrochloric acid, hydrofluoric acid etc.；The cation of quaternary ammonium salt can for tetramethyl-ammonium sun from Son, tetraethylammonium cation, tetrapropylammonium cation and tetrabutyl ammonium cation etc.；The anion of quaternary ammonium salt can be sulfuric acid Root, bisulfate ion, chlorion, bromide ion, bicarbonate radical etc..

3. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Homogeneous-phase anion exchange film DSV is used in described diffusion dialysis device.

4. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Certain flow is 0.1~0.9 L/h, preferably 0.1~0.3 L/h in described diffusion dialysis step.

5. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Anion-exchange membrane AMV is used in described electrodialysis plant and has the cation-exchange membrane of barriering effect to quaternary ammonium root cation CSO。

6. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Current density is used in described electrodialysis step for 100~600 A/m², preferably 100~300 A/m²。

7. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that BP-A-C structures are used in described bipolar membrane electrodialysis device, using Bipolar Membrane BP-1, anion-exchange membrane AMX and to quaternary ammonium The good cation-exchange membrane JCM of cationic ion permeability.

8. the process of organic wastewater of the processing containing free acid and quaternary ammonium salt according to claim 1, it is characterised in that Certain current density is 100~600 A/m in described bipolar membrane electrodialysis step², preferably 100~300 A/m²。