Updated: Mar 13, 2021
To remove the natural coloring matter and to obtain white material
The given cotton material is weighted accurately. The material is then steeped in the solution containing hydrogen peroxide, sodium silicate and sodium hydroxide at 40o c. The temperature of the solution is increased to 100o c and it is bleached for 120 minutes. Then it is subjected for hot wash, cold wash with water and it is dried.
In practice, normally oxidative bleaching is highly preferred for bleaching the textile substrates in industries. Reductive bleaching is not adopted due to the inefficient performance on cotton substrates and few limitations. Hydrogen Peroxide bleaching is an oxidative bleaching process applied to all kind of textile substrates. H2O2 is stable under neutral pH and it can be modified according to the suitability of the reaction. The operating pH for cellulosic is between 9-11.5; for proteins 2.5-6 & for synthetics is neutral pH.
In the alkaline condition the instability of peroxide is continued by the concentration. The liberation of nascent oxygen is utilized for the oxidation reaction in a controlled manner by selecting the stabilizers to get uniform application
The given cotton sample material was bleached and percentage of weight loss after bleaching was calculated.