[Chemical Knowledge]：Manufacturing method and process of industrial caustic soda

The manufacturing method
of industrial caustic soda
1. Introduction

industrial caustic soda, also known as sodium hydroxide, is an important inorganic chemical raw material, widely used in papermaking, printing and dyeing, chemical industry, metallurgy, medicine and other fields. Because of its wide application and importance, it is of great significance to study the manufacturing method of industrial caustic soda for improving production efficiency, reducing costs and improving product quality. This paper will introduce the manufacturing methods of industrial caustic soda, including brine method, diaphragm method and ion membrane method.

2. brine method

brine method is one of the most commonly used methods in industrial caustic soda production. The method takes salt as the main raw material and produces sodium hydroxide by electrolysis of sodium chloride aqueous solution. The specific steps are as follows:

1. Preparation of salt water solution: salt is dissolved in water to prepare a certain concentration of salt water solution.
2. electrolysis: salt water solution into the electrolytic cell, into the direct current for electrolysis. At the anode, the chloride ions lose electrons to generate chlorine gas; at the cathode, the hydrogen ions gain electrons to generate hydrogen gas and sodium hydroxide.
3. separation: sodium hydroxide is separated from chlorine and hydrogen by distillation to obtain pure sodium hydroxide.

brine process is simple, easy to operate, but the energy consumption is high, and a large amount of chlorine and hydrogen will be produced, which need to be properly treated.

3. diaphragm method

diaphragm method is another common method for industrial caustic soda production. The method uses salt as raw material, and uses diaphragm electrolytic cell to electrolyze salt solution to produce sodium hydroxide. The specific steps are as follows:

1. Preparation of salt water solution: salt is dissolved in water to prepare a certain concentration of salt water solution.
2. electrolysis: the salt water solution is passed into the diaphragm electrolytic cell, and the direct current is passed into the electrolysis. At the anode, the chloride ions lose electrons to generate chlorine gas; at the cathode, the hydrogen ions gain electrons to generate hydrogen gas and sodium hydroxide. The diaphragm separates the yin and yang poles to prevent a mixture of chlorine and hydrogen from exploding.
3. separation: sodium hydroxide is separated from chlorine and hydrogen by distillation to obtain pure sodium hydroxide.
the
diaphragm method has higher safety and production efficiency than the brine method, the equipment cost is higher.

4. ion membrane method

ion membrane method is a new industrial caustic soda manufacturing method developed in recent years. The method uses salt as raw material, and uses ion exchange membrane electrolytic cell to electrolyze salt solution to produce sodium hydroxide. The specific steps are as follows:

1. Preparation of salt water solution: salt is dissolved in water to prepare a certain concentration of salt water solution.
2. electrolysis: the salt water solution is passed into the ion exchange membrane electrolytic cell, and the direct current is passed for electrolysis. At the anode, the chloride ions lose electrons to generate chlorine gas; at the cathode, the hydrogen ions gain electrons to generate hydrogen gas and sodium hydroxide. The ion exchange membrane only allows sodium ions and water molecules to pass through, and prevents chloride ions and hydroxide ions from passing through, thereby achieving the separation of sodium hydroxide and chlorine.
3. Separation: The sodium hydroxide solution, chlorine gas and hydrogen gas are respectively led out through the discharge port. The sodium hydroxide solution is concentrated, crystallized and dried to obtain pure sodium hydroxide.

ion-exchange membrane method has the advantages of low energy consumption, high production efficiency and good product quality, which is the mainstream method of industrial caustic soda manufacturing.

5. Conclusion The main manufacturing methods of industrial caustic soda in

are brine method, diaphragm method and ion membrane method. Different methods have different advantages and disadvantages and scope of application, enterprises should choose suitable production methods according to their own actual situation. At the same time, with the continuous progress of science and technology and the continuous improvement of environmental protection requirements, the manufacturing methods of industrial caustic soda will also be constantly updated, towards a more efficient and environmentally friendly direction.