CN111472016A - A kind of method for preparing hydrogen peroxide by electrolytic recovery of sodium sulfate waste liquid - Google Patents

Abstract

The invention provides a method for preparing hydrogen peroxide by electrolytically recovering sodium sulfate waste liquid, comprising the following steps: step 1, purification; step 2, mixing and heating; step 3, electrolysis of sodium sulfate; and step 4, electrolysis to prepare hydrogen peroxide. The process of the invention operates in the mode of circulating liquid supply, with high production efficiency and low production cost; in the process of electrolyzing the sodium sulfate waste liquid, an anion and a cation double membrane are used for electrolysis, and the obtained sulfuric acid and sodium hydroxide are pure and free of impurities, and the product High concentration; no discharge of waste water, waste gas and waste residue, green and environmental protection; using a new electrolysis process for the production of hydrogen peroxide, the produced hydrogen peroxide product has high purity and good quality, and will not cause direct hydrogen and oxygen during the production process. Contact, almost no danger of burning; the whole process can not only ensure the effective treatment of sodium sulfate waste liquid, but also can produce hydrogen peroxide, sulfuric acid and sodium hydroxide solution, with high returns.

Description

A kind of method for preparing hydrogen peroxide by electrolytic recovery of sodium sulfate waste liquid

technical field

The invention relates to the field of industrial waste liquid recovery, in particular to a method for preparing hydrogen peroxide by electrolytically recovering sodium sulfate waste liquid

Background technique

In chemical production, hydrometallurgy, battery production and other fields, sodium sulfate waste liquid is one of the most common waste liquids. Although sodium sulfate itself does not cause harm to the environment, the eutrophication of water bodies caused by a large number of discharges still affects people's water safety. Therefore, many countries and regions in the world currently strictly control the discharge of sodium sulfate waste liquid.

Sulfuric acid is often used as a good leaching agent due to its low cost and strong acidity, and caustic soda is widely used in the field of chemical production as a good precipitant. The product obtained by the reaction of the two is sodium sulfate. Therefore, in chemical, metallurgical and other industrial production, a large amount of sodium sulfate waste liquid needs to be processed every day. Leaching, the acid consumption is huge (60 tons of acid per ton of nickel), and then the magnesium in magnesium sulfate needs to be precipitated with caustic soda, which will produce a large amount of sodium sulfate waste liquid (about 40 tons of sodium sulfate waste per ton of nickel) liquid); in the chemical beneficiation process of uranium ore, a large amount of sodium sulfate wastewater will also be produced because the pyrite in the uranium ore is oxidized to sulfate.

A method for treating the sodium sulfate waste liquid is to carry out evaporative crystallization. When using this method for concentration, it needs to be carried out at a high temperature, and the energy consumption is relatively large and the harm of acid mist is easy to be generated, and the obtained sodium sulfate crystals are of low value and far in return. Much lower than the cost of operation, this method has been gradually phased out. In addition to evaporative crystallization, the commonly used methods for treating sodium sulfate waste liquid are resin adsorption, membrane separation and multi-effect evaporation. Chinese patent document CN106517626A discloses a process for the treatment of sodium sulfate wastewater. The treatment steps of the method include evaporative concentration, evaporative crystallization and drying, etc., to realize the conversion of sodium sulfate waste liquid into commercial sodium sulfate crystals, and the energy consumption of the method is relatively high. Low, but a large amount of additives are needed to assist in the whole process flow, such as calcium hydrogen sulfite, calcium hydroxide, etc., the cost is high, and the industrial value of sodium sulfate is very low, so the income of the method is small. Based on the relatively mature ionic membrane electrolysis technology in the chlor-alkali process, Chinese patent document CN103060834A discloses a process for electrolyzing sodium sulfate. This method can realize the regeneration of sodium sulfate waste liquid into sulfuric acid and sodium hydroxide solution through continuous operation. Only single membrane is used for electrolysis, and the quality of the sulfuric acid produced is not high, and the cell voltage during electrolysis is too large, the energy consumption is large, and the production cost is too high. Therefore, finding a better recovery method of sodium sulfate waste liquid is of great benefit to environmental protection and resource recycling.

Hydrogen peroxide, also known as hydrogen peroxide, is often used as an excellent oxidant in the chemical industry because it produces water by chemical reaction when it is used as an oxidant, without the formation of toxic and harmful products. Moreover, due to the existence of peroxide bonds in hydrogen peroxide, hydrogen peroxide can destroy the nucleic acid structure of microorganisms such as bacteria and make them inactive. Therefore, hydrogen peroxide is also widely used as a disinfectant in food, medicine and other fields. In addition, the demand for hydrogen peroxide in related industries such as papermaking and textiles is also increasing. With the increasing demand for hydrogen peroxide in the domestic market, the production capacity of hydrogen peroxide is also increasing year by year, so the production process of hydrogen peroxide is also in urgent need of optimization.

The commonly used production process of hydrogen peroxide is represented by the high energy consumption anthraquinone process. The anthraquinone process uses alkyl anthraquinone as the working carrier, and uses various organic substances with high solubility for anthraquinone as the solvent to prepare the working solution. The working solution is obtained through the processes of hydrogenation, oxidation, extraction and purification, dehydration, and clay regeneration. The hydrogen peroxide product produced by this process typically yields a remaining mixture of impurities at a concentration of 1 to 2 wt % that requires further purification and distillation to reach concentrations suitable for commercial use. Hydrogen-oxygen synthesis method is one of the most environmentally friendly processes for producing hydrogen peroxide. This method directly synthesizes hydrogen and oxygen under high pressure and the action of a catalyst to produce hydrogen peroxide. In the past decade, the development of catalysts for this reaction has made good progress, such as palladium-tin catalysts with good selectivity (>95%) and extremely high production efficiency. However, the biggest disadvantage of this method is that the mixture of H ₂ and O ₂ is prone to combustion and explosion under high pressure, so in actual production practice, CO ₂ or N ₂ must be used as a carrier gas to dilute H ₂ a lot, so that Again, the yield of H ₂ O ₂ is greatly reduced. Therefore, researchers are devoted to finding a production method that can not only produce high-grade, high-purity H ₂ O ₂ products, but also safely realize the industrialization process.

SUMMARY OF THE INVENTION

The invention provides a method for preparing hydrogen peroxide by electrolytically recovering sodium sulfate waste liquid, and its purpose is to directly produce high-purity hydrogen peroxide while effectively recovering sodium sulfate waste liquid in an efficient and clean manner.

In order to achieve the above object, an embodiment of the present invention provides a method for preparing hydrogen peroxide by electrolytically recovering sodium sulfate waste liquid, comprising the following steps:

Step 1, Purify:

The sodium sulfate waste liquid is subjected to physical sedimentation and chemical purification to remove impurities in the solution to obtain a purified sodium sulfate solution;

Step 2, mix and warm up:

The purified sodium sulfate solution is heated in a sodium sulfate mixing tank, and fully mixed with dilute sulfuric acid, and the concentration of the sodium sulfate solution is adjusted by sodium sulfate crystals and electrolytic water;

Step 3, electrolysis of sodium sulfate:

The sodium sulfate solution, dilute sulfuric acid solution and dilute sodium hydroxide solution obtained after mixing and heating are respectively input into the electrolytic cell for electrolysis, wherein the sodium sulfate solution is input into the intermediate tank of the electrolytic cell through the liquid inlet of the intermediate tank, and the dilute sulfuric acid and dilute hydrogen The sodium oxide solution is input into the anode chamber of the electrolytic cell and the cathode chamber of the electrolytic cell through the liquid inlet of the anode chamber and the liquid inlet of the cathode chamber respectively, and the concentrated sulfuric acid and concentrated sodium hydroxide solution obtained by electrolysis pass through the liquid outlet of the anode chamber and the liquid of the cathode chamber respectively. Port output, the oxygen generated at the anode is transported to the hydrogen peroxide electrolysis cell through the oxygen pipeline of the hydrogen peroxide electrolysis cell, the hydrogen generated at the cathode is transported to the hydrogen peroxide electrolysis cell through the hydrogen gas pipeline of the hydrogen peroxide electrolysis cell, and the dilute sodium sulfate solution produced in the intermediate tank is discharged through the intermediate tank. The liquid port is transported to the sodium sulfate mixing tank and mixed with the purified sodium sulfate solution;

Step 4, prepare hydrogen peroxide by electrolysis:

The hydrogen and oxygen are input into the hydrogen peroxide electrolysis cell for electrolysis to obtain hydrogen peroxide, wherein hydrogen is input to the anode, oxygen is input to the cathode, and pure water is input into the porous solid electrolyte layer.

Preferably, in the step 3, the concentrated sulfuric acid solution generated in the anode chamber of the electrolytic cell is transported to the sulfuric acid mixing tank through the liquid outlet of the anode chamber, mixed with water for electrolysis to adjust the concentration and heated, and then transported to the sulfuric acid mixing tank through the liquid inlet of the anode chamber. Electrolyzer anode compartment.

Preferably, in the step 3, the concentrated sodium hydroxide solution produced in the cathode chamber of the electrolytic cell is transported to the sodium hydroxide mixing tank through the liquid outlet of the cathode chamber, mixed with water for electrolysis to adjust the concentration and heated, and then enters through the cathode chamber. The liquid port is transported to the cathode chamber of the electrolytic cell.

Preferably, in the step 3, the concentration of the sodium sulfate solution input into the middle tank of the electrolytic cell is 1.0-3.0 mol/L, the concentration of dilute sulfuric acid input into the anode chamber of the electrolytic cell is 0.1-2 mol/L, and the concentration of the dilute sulfuric acid input into the anode chamber of the electrolytic cell is 0.1-2 mol/L. The concentration of dilute sodium hydroxide is 0.1 to 2 mol/L.

Preferably, in the step 3, the temperature in the electrolytic cell is 40-70°C.

Preferably, in the step 3, the oxygen evolution anode of the electrolytic cell is a low oxygen evolution overpotential anode, and the hydrogen evolution cathode of the electrolytic cell is a low hydrogen evolution overpotential cathode.

Preferably, in the step 3, the cation exchange membrane of the electrolysis cell is a Nafion-117 type perfluorosulfonic acid ion membrane, and the anion exchange membrane of the electrolysis cell is an AMI-7001 type quaternary ammonium anion membrane.

Preferably, the hydrogen peroxide electrolytic cell is composed of a porous diffusion electrode, a cathode catalytic layer, an anode catalytic layer, an anion membrane of an electrolytic cell, a cationic membrane of an electrolytic cell, and a porous solid electrolyte.

Preferably, the porous diffusion electrode is a Sigracet 35 BC gas diffusion electrode, the anode catalyst layer is a platinum carbon catalyst layer, and the cathode catalyst layer is a commercial carbon black layer oxidized by nitric acid.

Preferably, the hydrogen peroxide obtained in the step 4 is sent to the step 1 for purification of the sodium sulfate waste liquid.

The above-mentioned scheme of the present invention has the following beneficial effects:

(1) The process adopts the mode of circulating liquid supply, with high production efficiency and low production cost;

(2) in the process of electrolysis of sodium sulfate waste liquid, the double membranes of anions and cations are used for electrolysis, and the obtained sulfuric acid and sodium hydroxide are pure and free of impurities, and the product concentration is high;

(3) The process flow does not discharge any waste water, waste gas and waste residue, and is green and environmentally friendly;

(4) The effective treatment of sodium sulfate waste liquid can be ensured in the whole process, and hydrogen peroxide, sulfuric acid and sodium hydroxide solution can be produced simultaneously, and the income is high;

(5) The production of hydrogen peroxide is carried out by adopting a new electrolysis process, and the produced hydrogen peroxide product has high purity and good quality, and does not cause direct contact between hydrogen and oxygen during the production process, and almost no danger of burning occurs;

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

FIG. 2 is a schematic diagram of the process of the present invention.

[Description of reference numerals]

1- Oxygen pipeline of hydrogen peroxide electrolysis cell; 2- Gas pressure reducing valve; 3- Porous diffusion electrode; 4- Cathode catalytic layer; 5- Pure water inlet; 6- Electrolytic cell anion membrane; 7- Electrolytic cell cationic membrane; 8 -Anode catalytic layer; 9-Hydrogen peroxide liquid outlet; 10-Porous solid electrolyte layer; 11-Hydrogen gas electrolysis cell hydrogen pipeline; 12-Electrolyzer cathode chamber; 13-Cathode chamber liquid outlet; 14-Cathode chamber liquid inlet; 15-hydrogen evolution cathode; 16-electrolyzer cation exchange membrane; 17-middle tank liquid inlet; 18-middle tank liquid outlet; 19-electrolyzer anion exchange membrane; 20-electrolyzer middle tank; 21-oxygen evolution anode; 22-anode chamber of the electrolytic cell; 23-anode chamber liquid inlet; 24-anode chamber liquid outlet.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1 and Figure 2, an embodiment of the present invention provides a kind of method for preparing hydrogen peroxide by electrolytic recovery of sodium sulfate waste liquid, comprising the following steps:

Step 1: Use the leaching solution of the positive electrode material of the waste ternary lithium ion battery as the electrolyte stock solution, the main component of which is sodium sulfate solution, containing a small amount of Co ²⁺ , Mn ²⁺ , and Ni ²⁺ . Use suction filtration equipment to filter and purify the original solution to remove insoluble impurities in the sodium sulfate waste liquid, and the filtered solution is clear and transparent;

The filtered solution was subjected to resin adsorption, and two plexiglass resin columns were connected in parallel, and the columns were filled with D751 chelating resin. When one resin column is adsorbed, the other one is desorbed to achieve continuous operation. When the Co ²⁺ , Mn ²⁺ , Ni ²⁺ in the solution after adsorption exceeds 30ppb, change another resin for adsorption, and the original working resin column begins to desorb;

Step 2: the solution after the adsorption is completed enters the sodium sulfate mixing tank, is mixed with the dilute sodium sulfate solution output from the intermediate tank 20 after electrolysis, and is heated, wherein the stirring rate is 50r/min, and the solution temperature is 50 ℃ (±2 ℃), After mixing, the concentration of sodium sulfate solution is 2.0mol/L, and then it is transported by a circulating pump, and is input into the intermediate tank 20 through the intermediate tank liquid inlet 17 for electrolysis. The concentration of dilute sulfuric acid at the liquid inlet 23 of the anode chamber of the electrolytic cell is 0.5mol/L, the concentration of the dilute sodium hydroxide solution at the liquid inlet 14 of the cathode chamber is 0.5mol/L, and the temperature in the cell is controlled to 50°C (±2°C).

Step 3: The electrolytic cell uses the titanium-plated Ir-Ru coating electrode as the oxygen evolution anode 21 with low oxygen evolution overpotential, the nickel-plated Pd-Ag coating electrode as the hydrogen evolution cathode 15 with low hydrogen evolution overpotential, and uses the Nafion-117 type The perfluorosulfonic acid ion membrane is used as the cation exchange membrane 16 of the electrolytic cell, and the AMI-7001 quaternary ammonium anion membrane is used as the anion exchange membrane ¹⁹ of the electrolytic cell. The concentration of the generated concentrated sulfuric acid solution is 1.48mol/L, and a part is transported to the sulfuric acid mixing tank through the anode chamber liquid outlet 24 for heating, and mixed with water for electrolysis to adjust the concentration to 0.5mol/L, and then passes through the anode chamber liquid inlet 23 It is transported to the anode chamber 22 of the electrolytic cell, and another part of the concentrated sulfuric acid solution is directly used as a product of electrolysis for process use or sale; the concentration of the concentrated sodium hydroxide solution generated in the cathode chamber 12 is 1.57 mol/L, and a part passes through the cathode chamber liquid outlet 13 It is exported to the sodium hydroxide mixing tank for heating, and mixed with water for electrolysis to adjust the concentration to 0.5mol/L, and then transported to the cathode chamber 12 of the electrolytic cell through the liquid inlet 14 of the cathode chamber, and another part of the concentrated sodium hydroxide solution is directly used as The electrolyzed product is used or sold in the process; the dilute sodium sulfate solution produced by the intermediate tank 20 is transported to the sodium sulfate mixing tank through the intermediate tank liquid outlet 18, and mixed with the purified sodium sulfate solution; the oxygen generated in the anode chamber 22 It is transported into the hydrogen peroxide electrolysis cell through the oxygen pipeline 1 of the hydrogen peroxide electrolysis cell, and the hydrogen generated in the cathode chamber 12 is transported to the hydrogen peroxide electrolysis cell through the hydrogen peroxide electrolysis cell hydrogen pipeline 11; after calculation, the electrolysis rate of sodium sulfate is 76%, and the current efficiency is 83%.

Step 4: The hydrogen peroxide electrolysis cell is composed of a porous diffusion electrode 3 , a cathode catalytic layer 4 , an anode catalytic layer 8 , an anion membrane 6 of an electrolysis cell, a cationic membrane 7 of an electrolysis cell and a porous solid electrolyte 10 . Among them, Sigravet 35 BC gas diffusion electrode is used as porous diffusion electrode 3, platinum carbon catalyst layer is used as anode catalyst layer 8, and commercial carbon black layer oxidized by 10%-15% of nitric acid surface is used as cathode catalyst layer 4.

The hydrogen and oxygen obtained in step 3 are respectively introduced into the anode chamber of the hydrogen peroxide electrolysis cell and the cathode chamber of the electrolysis cell through the gas pressure reducing valve 2, and pure water is slowly introduced into the porous solid electrolyte layer 10 through the pure water inlet 5. During the electrolysis process, the current density was 2kA/m ² , and the mass fraction of the obtained product hydrogen peroxide was 15wt%.

The process of the invention operates in the mode of circulating liquid supply, with high production efficiency and low production cost; in the process of electrolyzing the sodium sulfate waste liquid, an anion and a cation double membrane are used for electrolysis, and the obtained sulfuric acid and sodium hydroxide are pure and free of impurities, and the product High concentration; no discharge of waste water, waste gas and waste residue, green and environmental protection; using a new electrolysis process for the production of hydrogen peroxide, the produced hydrogen peroxide product has high purity and good quality, and will not cause direct hydrogen and oxygen during the production process. Contact, almost no danger of burning; the whole process can not only ensure the effective treatment of sodium sulfate waste liquid, but also can produce hydrogen peroxide, sulfuric acid and sodium hydroxide solution, with high returns.

The above are the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A method for preparing hydrogen peroxide by electrolyzing and recovering sodium sulfate waste liquid is characterized by comprising the following steps:

step 1, purification:

removing impurities in the sodium sulfate waste liquid through physical sedimentation and chemical purification to obtain a purified sodium sulfate solution;

step 2, mixing and heating:

heating the purified sodium sulfate solution in a sodium sulfate mixing tank, heating, fully mixing with dilute sulfuric acid, and adjusting the concentration of the sodium sulfate solution by using sodium sulfate crystals and electrolysis water;

step 3, electrolyzing sodium sulfate:

respectively inputting a sodium sulfate solution, a dilute sulfuric acid solution and a dilute sodium hydroxide solution which are obtained after mixing and heating into an electrolytic cell for electrolysis, wherein the sodium sulfate solution is input into the electrolytic cell intermediate tank through an intermediate tank liquid inlet, the dilute sulfuric acid and the dilute sodium hydroxide solution are respectively input into an electrolytic cell anode chamber and an electrolytic cell cathode chamber through an anode chamber liquid inlet and a cathode chamber liquid inlet, concentrated sulfuric acid and a concentrated sodium hydroxide solution are obtained through electrolysis and are respectively output through an anode chamber liquid outlet and a cathode chamber liquid outlet, oxygen generated at an anode is conveyed into a hydrogen peroxide electrolytic cell through a hydrogen peroxide electrolytic cell oxygen pipeline, hydrogen generated at a cathode is conveyed into a hydrogen peroxide electrolytic cell through a hydrogen peroxide electrolytic cell hydrogen pipeline, and the dilute sodium sulfate solution generated at the intermediate tank is conveyed into a sodium sulfate mixing tank through the intermediate tank liquid outlet and is mixed with;

step 4, preparing hydrogen peroxide by electrolysis:

and inputting hydrogen and oxygen into a hydrogen peroxide water electrolysis cell for electrolysis to obtain hydrogen peroxide, wherein the hydrogen is input into the anode, the oxygen is input into the cathode, and pure water is input into the porous solid electrolyte layer.

2. The method for preparing hydrogen peroxide by electrolyzing and recycling sodium sulfate waste liquid as claimed in claim 1, wherein the concentrated sulfuric acid solution generated in the anode chamber of the electrolytic cell in the step 3 is delivered to a sulfuric acid mixing tank through a liquid outlet of the anode chamber, mixed with water for electrolysis to adjust the concentration and heated, and then delivered to the anode chamber of the electrolytic cell through a liquid inlet of the anode chamber.

3. The method for preparing hydrogen peroxide by electrolyzing and recovering the sodium sulfate waste liquid as claimed in claim 2, wherein the concentrated sodium hydroxide solution produced in the cathode chamber of the electrolytic cell in the step 3 is conveyed to a sodium hydroxide mixing tank through a liquid outlet of the cathode chamber, mixed with water for electrolysis to adjust the concentration and heated, and then conveyed to the cathode chamber of the electrolytic cell through a liquid inlet of the cathode chamber.

4. The method for preparing hydrogen peroxide by electrolyzing and recycling the sodium sulfate waste liquid as claimed in claim 3, wherein in the step 3, the concentration of the sodium sulfate solution input into the middle tank of the electrolytic cell is 1.0-3.0 mol/L, the concentration of the dilute sulfuric acid input into the anode chamber of the electrolytic cell is 0.1-2 mol/L, and the concentration of the dilute sodium hydroxide input into the cathode chamber of the electrolytic cell is 0.1-2 mol/L.

5. The method for preparing hydrogen peroxide by electrolyzing the recovered sodium sulfate waste liquid as claimed in claim 4, wherein in the step 3, the temperature in the electrolytic cell is 40-70 ℃.

6. The method for preparing hydrogen peroxide by electrolyzing and recovering the sodium sulfate waste liquid as claimed in claim 5, wherein in the step 3, the oxygen evolution anode of the electrolytic cell is a low oxygen evolution overpotential anode, and the hydrogen evolution cathode of the electrolytic cell is a low hydrogen evolution overpotential cathode.

7. The method for preparing hydrogen peroxide by electrolyzing and recycling sodium sulfate waste liquid according to claim 6, wherein in the step 3, an electrolytic cell cation exchange membrane is a Nafion-117 type perfluorosulfonic acid ion membrane, and an electrolytic cell anion exchange membrane is an AMI-7001 type quaternary ammonium anion membrane.

8. The method for preparing hydrogen peroxide by electrolyzing and recovering sodium sulfate waste liquid as claimed in claim 7, wherein the hydrogen peroxide water electrolysis cell is composed of a porous diffusion electrode, a cathode catalyst layer, an anode catalyst layer, an electrolytic cell anion membrane, an electrolytic cell cation membrane and a porous solid electrolyte.

9. The method for preparing hydrogen peroxide by electrolyzing recovered sodium sulfate waste liquid as claimed in claim 8, wherein the porous diffusion electrode is a Sigracet 35BC gas diffusion electrode, the anode catalytic layer is a platinum carbon catalytic layer, and the cathode catalytic layer is a commercial carbon black layer oxidized by nitric acid.

10. The method for preparing hydrogen peroxide by electrolyzing and recycling the sodium sulfate waste liquid as claimed in claim 9, wherein the hydrogen peroxide obtained in the step 4 is delivered to the step one for purification of the sodium sulfate waste liquid.

Images