It is a powerful germicide and insecticide. It is used as disinfectant.When sulphur dioxide combines with water nascent hydrogen is liberated which bleaches the delicate fibres. Hence it is used as a bleaching agent.
It is a mild bleaching agent. It is used for bleaching delicate fibers like silk, wool etc.Industrial and Small Scale Uses of Sulphur DiOxideIt acts as a reducing agent, the halogens will be reduced as hydrogen chlorideSO2 + 2H2O + Cl2 --------- 2HCl + H2SO4It removes excess chlorine from bleached article. It is used as an antichlor.It undergoes easily liquefaction and vapourisation.
It is used as refrigerant in cold storage plants.Industrial usesIn the manufacture of sulphuric acid by contact process it is used as a raw material which is obtained by the burning of iron pyrites. Then it is oxidized to sulphur trioxide which dissolves with water giving sulphuric acid.In the paper industry sulphur di oxide is used for the manufacture of calcium bisulphate which is used in treating wood pulp.Sulphur dioxide decolourises cane sugar.
In sugar industry it is used for refining sugar.It can be used as a reducing agent in metallurgy.It is an inert solvent. It acts as a solvent for dissolving oxidizing salts.Dried fruits will be discoloured. To prevent this sulphur dioxide is used.In the wine industry it is used as an antibiotic and antioxidant.Wine will not be spoiled by Bacteria or oxidation.
Winery sanitation:Hoses, tanks and equipments are cleaned by a mixture of sulphur dioxide water and citric acid.When it is dissolved in wine it exists in ionized form. This is acting as an antioxidant.In the preparation of sulphate saltsWhen sulphur dioxide reacts with sodium hydroxide solution sodium bisulphite will formNaOH + SO2 ---- NaHSO3More uses of Sulphur DiOxideIn the production cobalt sulphur dioxide is used as a reducing agent.The Co2+ ion will be converted to Co3+ ion.which become soluble. This process is called as cobalt leaching.It is used as a preservative in meat.It slows down the growth of bacteria.It is used in the preparation of some fertilizers like ammonium sulphate.
The gas is oxidized and treated with water to form sulphuric acid . Then ammonia gas reacts with this acid giving ammonium sulphate which is a good fertilizer.Fruit puree can be stored by using sulphur dioxide. The puree is to be boiled before adding sulphur dioxide. When the puree dries the sulphur dioxide is slowly lost. So the puree is boiled.This way it can be stored for six months.