Anhydrous sodium sulfate is an inorganic compound, also known as thenardite, which is characterized by its high melting point. Its chemical equation is Na2SO4. It is a white crystalline powder. Although soluble in water, it has an affinity for organic compounds and is widely used as a drying agent in organic synthesis.
The present invention is based on treating a saturated solution of sodium sulfate with an organic liquid precipitant. A substantial amount of the sulfate is removed from the solution without requiring large amounts of evaporation. This enables the sulfate to precipitate in anhydrous form without inhibition.
Glauber’s salt is a type of sodium sulfate, and is generally dehydrated. After a period of storage in a refrigerator, it is separated from the mother liquor. This is done by using a mechanical vapor recompression evaporator.
During the process, a first sulfate precipitate forms, which then is retained as suspension in the solution. This is beneficial, as it provides a large surface area for growing the desired sulfate.
The resulting sulfate is then treated with a reducing agent to convert ferric iron to ferrous iron. Afterwards, the ferric iron is removed from the solution.
After the final sulfate precipitation, the sulfate content of the resulting solution is as low as 26.6%. As such, the excess sulfate content is less than 1% of the equilibrium solution.
Glauber’s salt is commonly used as a drying agent, particularly in aqueous organic extractions. When used in this way, anhydrous sodium sulfate is generally more effective than magnesium sulfate.