How to Manufacture Sodium Hydroxide
Sodium hydroxide, also known as caustic soda or caustic soda, is an inorganic compound that is strongly alkaline. It has a wide range of applications in the field of raw materials for the production of chemicals, so it is especially important to understand its manufacturing method. This article will introduce the manufacturing method of sodium hydroxide in detail.
I. Diaphragm method
The diaphragm method is the main method of sodium hydroxide production, and its output accounts for about 90% or more of the total output of sodium hydroxide. The main principle of this method is to electrolyze the aqueous solution of table salt to produce sodium hydroxide, hydrogen and chlorine. The diaphragm method electrolyzer is mainly composed of anode, cathode and diaphragm, which prevents hydrogen and chlorine gas from mixing and exploding. During the electrolysis process, sodium chloride in the saline solution loses electrons at the anode to generate chlorine, and hydrogen ions in the water get electrons at the cathode to generate hydrogen, while the remaining hydroxide ions combine with sodium ions to generate sodium hydroxide.
II. Ionic membrane method
Ionic membrane method is another manufacturing method of sodium hydroxide. Unlike the diaphragm method, the diaphragm used in the ionic membrane method is an ion-exchange membrane, which allows only sodium ions to pass through, but not hydrogen and chloride ions. As a result, the ionic membrane method is able to prevent hydrogen and chlorine from mixing more effectively, improving production safety. At the same time, due to the selectivity of the ionic membrane, higher purity sodium hydroxide products can be obtained.
Three, mercury method
The mercury method is an older method of manufacturing sodium hydroxide. The method uses mercury as the cathode to generate sodium hydroxide and chlorine gas by electrolyzing a solution of table salt water. However, because mercury is toxic and harmful to the environment and human health, the method has been gradually eliminated.
IV. Molten Salt Method
The molten salt method is a new method of manufacturing sodium hydroxide. This method uses molten salt as the electrolyte, and electrolyzes the water in the molten salt at high temperature to generate hydrogen and sodium hydroxide. Since the molten salt has high conductivity and good thermal stability, the electrolysis efficiency and production safety can be improved. However, the method requires high-temperature conditions and special equipment, resulting in higher production costs.
In conclusion, there are various manufacturing methods of sodium hydroxide, among which diaphragm method and ionic membrane method are the main production methods at present. In the actual production, the suitable manufacturing method should be selected according to the specific situation and demand, in order to obtain high-quality and high-purity sodium hydroxide products.
