The Theory and Practice of Sodium Chlorite Bleaching

Abstract

The decomposition of sodium chlorite during the bleaching of flax has been studied at different pH values and various temperatures. Bleaching with sodium chlorite should be accompanied by maximum formation of sodium chloride and minimum formation of sodium chlorate and chlorine dioxide. The oxidising power of the bleaching agent is discussed. Whilst there is a good margin of safety with sodium chlorite under normal bleaching conditions, extreme conditions must be avoided, in order to prevent chemical damage. The effect of sodium chlorite on the impurities present in cotton and flax is discussed. The use of hot, weakly acid oxidising solutions permits shortened bleaching processes. The main problems in practical sodium chlorite bleaching are (1) choice of a suitable method of activation of the bleaching agent, (2) selection of corrosion-resistant materials for construction of bleaching plant, and (3) design of the equipment to be used.