Sodium sulphate is a chemical compound, the sodium salt of sulphuric acid and is also known, as anhydrous, under the name Gauber's salt.  It is produced by neutralising sulphuric acid with sodium hydroxide, but exists in nature in the minerals mirabilite and thenardite.

Chemically, it is very stable and does not decompose even at normal temperatures of 38-40°. It is a neutral salt with a pH of 7 when diluted in water.

It appears in the form of a white powder. 

What it is used for and where

Food

Ingredient listed in the European food additives list as E514, acidity regulator. It is also used as food salt, in steam that comes into contact with food (21CFR173.310), in chewing gum substances (21CFR172.615), in cotton and cotton fabric in dry food wrappers (21CFR186.1797).

Cosmetics

Bulking agent. It regulates the water content, dilutes other solids, can increase the volume of a product for better flow, acts as a buffer against organic acids, helps to keep the pH of the mixture within a certain level.

Viscosity control agent. It controls and adapts viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

Medical

Sodium sulphate is an ingredient in laxative drugs for colon examination, colonoscopy.

FDA approved up to 1.2% (ophthalmic), up to 0.03% (inhalation), up to 182 mg (oral) and up to 1.14% (intravenous) (1).

Safety

The Panel on the Safety of Cosmetic Ingredients concluded that sodium sulphate is safe in cosmetics in the current use practices and concentrations described in this safety assessment when formulated to be nonirritating. (2).

Other uses

• food packaging and in substances used as "basic components in single-use and repeated food contact surfaces" in the section on cellophane (21CFR177.1200). 
• as a filler in washing powders
• in wood production
• in the production of paper and paperboard packaging

Sodium sulphate studies

Molecular Formula: Na₂SO₄   Na₂O₄S

Molecular Weight: 142.036 g/mol

UNII: 36KCS0R750

CAS: 7757-82-6  68412-82-8  68140-10-3  67762-51-0  68081-98-1  1337-28-6  15124-09-1  856314-01-7  1079994-54-9

EC Number: 231-820-9  268-366-6  268-773-9  270-211-2

PubChem Substance ID 329752527

MDL number MFCD00003504

Synonyms:

• Disodium sulfate
• Gauber's salt
• Salt cake
• Sodium sulphate
• sodiumsulfate
• Bisodium sulfate
• Thenardite
• Sulfuric acid disodium salt
• Sodium sulfate anhydrous
• Disodium sulphate
• Sodium sulfate (2:1)
• Sodium sulfate, anhydrous
• Disodium monosulfate
• Sulfuric acid, sodium salt
• Dibasic sodium sulfate
• Natriumsufat
• Natriumsulfat (German)
• Sodium sulphate anhydrous
• Sulfate, sodium

References_____________________________________________________________________

(1) Inactive Ingredient Search for Approved Drug Products (fda.gov) 

(2) Scott LN, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG Jr, Shank RC, Slaga TJ, Snyder PW, Gill LJ, Heldreth B. Final Amended Safety Assessment of Sodium Sulfate as Used in Cosmetics. Int J Toxicol. 2021 Jul-Aug;40(1_suppl):86S-94S. doi: 10.1177/10915818211015921.