How Does Alumina React To Get Aluminum Hydroxide

There are many methods for preparing aluminum hydroxide, such as Bayer method, soda lime sintering method, ammonium bicarbonate method, etc. In fact, the reaction of alumina is also a good preparation method. The specific reaction process is as follows:

Because aluminum oxide is an amphoteric oxide that is hard to dissolve in water, and aluminum hydroxide is an amphoteric hydroxide that is hard to dissolve in water. Soluble in carbonic acid (weak acid). Therefore, the following methods can be used to prepare:

1. Dissolve aluminum oxide in sulfuric acid to obtain an aluminum sulfate solution, then add excess ammonia to the aluminum sulfate solution to obtain aluminum hydroxide precipitate, which can be filtered, washed, and dried.

Al2O3+3H2SO4=Al2(SO4)3+3H2O

Al2(SO4)3+6NH3.H2O=2Al(OH)3↓+3(NH4)2SO4

2. Dissolve aluminum oxide in sodium hydroxide to obtain a sodium metaaluminate solution, and then pass excess carbon dioxide into the sodium metaaluminate solution to obtain aluminum hydroxide, which can be precipitated, filtered, washed, and dried.

It should be noted that during the preparation process, the purpose of adding excessive ammonia water and carbon dioxide is to ensure that the alumina can be completely converted into aluminum hydroxide to obtain a purer product.