Sodium Sulfate, also known as anhydrous Glauber's salt or Anhydrous Mirabilite, appears as white monoclinic crystal or fine powder with the relative density being 2.68 and the melting point being 884 ℃. It can be dissolved in water with the aqueous solution being neutral. It is soluble in glycerol and insoluble in ethanol. It is easy to absorb water when being exposed to become hydrous sodium sulfate. It is a homogeneous polycrystalline material and is rhombus at a temperature of 32.4~223 ℃ with generating shaped monoclinic crystal at higher temperatures and generating hexagonal crystals in 241 ℃. When being crystallized from solution, it has high affinity to iron, iron compound and various kinds of other organic compounds.
There are two kinds of crystalline hydrate compound of sodium sulfate: one is heptahydrate sodium sulfate Na2SO4·7H2O, being white sixty or tetragonal crystal with dehydrating at 24.4 ℃. Another is sodium sulfate decahydrate Na2SO4·10H2O with conventional name being Glauber's salt.
Uses:
Sodium sulfate is an important raw material in the manufacturing of glass and paper with the maximum usage amount in the paper and cellulose industry which accounts for around 70% of the total amount. Sodium sulfate is the component of synthetic detergent and is a neutral salt. It can be added to the detergent to reduce the surface tension as well as increases the solubility of the detergent. It is also be used as the dye diluent and the auxiliary agent of the dye printing, as direct dyes, sulfur dyes, vat dyes and other accelerant of dyed cotton fiber, as retarding agent for direct dye silk. In the chemical industry, it can be used as the raw material for the manufacturing of sodium sulfide, gypsum, sodium silicate and other chemical products. It has been now developed of the method for making sulfuric acid, sulfur, soda ash, ammonium sulfate and other products with sodium sulfate. However, due to the high cost of these methods, it has not yet been widely applied. It has been commonly used by laboratory system for using sodium sulfate as cold agent. Glauber's salt has been used as a laxative medicine. The sodium sulfate entering into the body is largely stuck in the gastrointestinal tract without being absorbed and being maintained at certain penetration. It can increase the volume of the intestines and induce intestinal peristalsis with diarrhea effect. Sodium sulfate is the antidote of barium and lead poisoning. Upon lead poisoning, people can apply gastric lavage with 10% Glauber's salt or orally administer 1 to 2% sodium sulfate solution.
