Because sodium carbonate hydrolyzes in an aqueous solution, the ionized carbonate ions combine with hydrogen ions in the water to form bicarbonate ions, resulting in a decrease in hydrogen ions in the solution, leaving ionized hydroxide ions, so the solution The pH is alkaline, so it is called soda ash.
Before the artificial synthesis of soda ash, it was discovered in ancient times that the ashes burned after drying certain seaweeds contained alkali. After leaching with hot water and filtering, brown alkali solution could be obtained for washing. A large amount of trona comes from minerals, mainly buried underground or alkaline lakes. Trona minerals that exist in sedimentary layers have the highest grade and are widely distributed.
The earliest invention of the method of artificially synthesizing soda ash was at the end of the 18th century. France's Lou Blanc used Glauber's salt, limestone and coal to reduce and carbonate it at high temperatures to obtain a crude product - black ash, mainly containing Na2CO3. After leaching, evaporation, refining, recrystallization and drying, heavy soda ash with a purity of approximately 97% is obtained. In 1861, Belgian E. Solvay independently invented soda ash and obtained a patent.
Because technical secret protection has never been widely used, a breakthrough was made in the United States in the 1920s. In particular, Hou Debang, a famous Chinese chemical expert, published the book "Soda Ash Manufacturing" in 1932, keeping it secret for 70 years. In 2001, the Solvay Law was announced to the world.
Hou Debang also created Hou's alkali production method from 1939 to 1942, and established a pilot plant in Sichuan. In 1952, a joint alkali production workshop was established in Dalian Chemical Plant. The NA method introduced by Japan's Asahi Glass Co., Ltd. is essentially a compromise method between joint alkali and ammonia-alkali. The ratio of soda ash and ammonium chloride can be adjusted at will.
Extended information:
Health hazards:
This product is weakly irritating and weakly corrosive. Direct contact may cause skin and eye burns. Inhaling its dust and smoke during production can cause respiratory tract irritation and conjunctivitis, as well as nasal mucosal ulcers, atrophy and nasal septum perforation.
Prolonged exposure to this product solution may cause eczema, dermatitis, corn-like ulcers and skin laxity. Workers exposed to this product have an increased incidence of respiratory diseases. Mistaken use can cause gastrointestinal burns, mucosal erosion, bleeding and shock.
Baidu Encyclopedia-Soda Ash