Ammonium Sulphate

Brief Overview

Ammonium sulphate is an inorganic salt with the chemical formula (NH₄)₂SO₄. Ammonium sulphate has various industrial applications but should also be handled carefully as it can be highly hazardous to humans. Its primary use is as a fertilizer for agriculture, containing 21% nitrogen and 24% sulphur. Ammonium sulphate occurs in nature in the form of a mineral called mascagnite. Mascagnite is a rare mineral and is present in volcanic fumaroles and coal fire dumps.

Manufacturing Process

Ammonium sulphate is prepared by treating ammonia with sulphuric acid. The chemical reaction is written as:

2NH₃ + H₂SO₄ → (NH₄)₂SO₄

Another method of preparing ammonium sulphate is adding gypsum salt to an ammonium carbonate solution. Calcium carbonate and ammonium sulphate are the products of the reaction. The calcium carbonate is precipitated from the mixture, leaving an ammonium sulfate solution behind.

Food Industry 

Ammonium sulphate is used as an acidity regulator in flour and bread, and the food grade ammonium sulphate is recognized as safe by the US FDA and the European Union.

Agriculture Industry

Ammonium sulphate is used as a fertilizer for crops grown on alkaline soil. When ammonium sulphate is added to alkaline soil, ammonium ions are released along with a small amount of acid, which lowers the pH of the soil. Apart from this, it also acts as a nitrogen source for plant growth.

Horticulture Industry

Ammonium sulphate is used in horticulture as a spray adjuvant for water-soluble insecticides, herbicides, and fungicides. Its function is to bind the iron and calcium cations that are present in the water.

Analytical Uses

Ammonium sulphate is used for purifying proteins by selective precipitation or salting out the protein from the solution, thus providing a simple way of fractionating complex protein mixtures.

Other Applications

Ammonium sulphate is listed as an ingredient for many US vaccines by the Centre for Disease Control.