What is the bleaching action of sulphur dioxide?

Sulphur dioxide is a temporary bleaching agent, unlike Chlorine, which is a permanent bleaching agent! This is because the mechanism for bleaching is different: * SO2-Reduction => TEMPORARY * Cl2-Oxidation => PERMANENT Sulphur dioxide removes oxyg... read more

The bleaching action sulphur dioxide is due to its reducing action. The colour of pigment on exposure to SO2 gets reduced to a colourless compound. On standing in an air the colourless reduced product is reoxidised and gain the original colour. Bleaching with sulphur dioxide is therefore of temporary nature. read more

Moisture for bleaching action. Differences - The bleaching action by chlorine is based on Oxidation means it requires nascent oxygen for Bleaching action. While sulphur dioxide bleaching is based upon the reduction (Use of the nascent hydrogen) Another difference is the bleaching action of sulphur dioxide is temporary while bleaching Action of chlorine is permanent. read more