Manufacturing Method of Industrial Caustic Soda
I. Introduction
Industrial caustic soda, also known as sodium hydroxide, is an important inorganic chemical raw material widely used in various fields such as papermaking, printing and dyeing, chemical industry, metallurgy, medicine and so on. Due to its wide application and importance, the study of the manufacturing method of industrial caustic soda is of great significance to improve the production efficiency, reduce the cost and improve the product quality. In this paper, we will introduce the manufacturing methods of industrial caustic soda, including brine method, diaphragm method and ionic membrane method.
II. Brine method
The brine method is one of the most commonly used methods in the production of industrial caustic soda. The method takes table salt as the main raw material and produces sodium hydroxide by electrolyzing aqueous sodium chloride solution. The specific steps are as follows:
1. Preparation of aqueous salt solution: dissolve table salt in water and prepare a certain concentration of aqueous salt solution.
2. Electrolysis: The aqueous salt solution is passed into an electrolyzer, and direct current is passed through for electrolysis. At the anode, chloride ions lose electrons to form chlorine gas; at the cathode, hydrogen ions gain electrons to form hydrogen gas and sodium hydroxide.
3. Separation: Sodium hydroxide is separated from chlorine gas and hydrogen gas by distillation to obtain pure sodium hydroxide.
The brine method is a simple process and easy to operate, but it consumes high energy and also produces a large amount of chlorine and hydrogen, which needs to be properly disposed of.
Third, diaphragm method
Diaphragm method is another common method for industrial caustic soda production. This method takes table salt as raw material, and uses diaphragm electrolyzer to electrolyze aqueous solution of table salt to produce sodium hydroxide. Specific steps are as follows:
1. Preparation of aqueous salt solution: dissolve table salt in water and prepare a certain concentration of aqueous salt solution.
2. Electrolysis: The aqueous salt solution is passed into a diaphragm electrolyzer, which is energized with direct current for electrolysis. At the anode, chloride ions lose electrons to form chlorine gas; at the cathode, hydrogen ions gain electrons to form hydrogen gas and sodium hydroxide. The diaphragm separates the cathode from the anode and prevents the chlorine and hydrogen from mixing and 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, but the cost of equipment is higher.
Four, ionic membrane method
Ionic membrane method is a new type of industrial caustic soda manufacturing method developed in recent years. The method takes table salt as raw material, and uses ion exchange membrane electrolyzer to electrolyze aqueous solution of table salt to produce sodium hydroxide. The specific steps are as follows:
1. Preparation of aqueous salt solution: dissolve table salt in water and prepare a certain concentration of aqueous salt solution.
2. Electrolysis: Pass the aqueous salt solution into the ion exchange membrane electrolyzer and pass direct current for electrolysis. At the anode, chloride ions lose electrons to produce chlorine gas; at the cathode, hydrogen ions gain electrons to produce hydrogen gas and sodium hydroxide. The ion exchange membrane allows only sodium ions and water molecules to pass through, preventing chlorine ions and hydroxide ions from passing through, thus realizing the separation of sodium hydroxide and chlorine gas.
3. Separation: Sodium hydroxide solution and chlorine gas and hydrogen gas are separately led out through the discharge port, and the sodium hydroxide solution is concentrated, crystallized and dried to obtain pure sodium hydroxide.
Ion membrane method has the advantages of low energy consumption, high production efficiency, good product quality and so on, it is the mainstream method of industrial caustic soda manufacturing at present.
V. Conclusion
The manufacturing methods of industrial caustic soda mainly include brine method, diaphragm method and ionic membrane method. Different methods have different advantages and disadvantages and scope of application, and enterprises should choose the suitable production method according to their actual situation. At the same time, with the continuous progress of science and technology and environmental protection requirements, the manufacturing methods of industrial caustic soda will be constantly updated and modernized, and develop in the direction of more efficient and environmental protection.
