Factors affecting hydrogen peroxide bleaching:
Table of Contents
The effects of hydrogen peroxide bleaching are as follows:
1. Effect of Temperature
2. Effect of Catalyst
3. Effect of stabilizer
4. Effect of Alkali
5. Effect of water
6. Effect of cotton impurities
1. Effect of Temperature:
The stability of hydrogen peroxide decreases with increasing temperature. Bleaching below 40°C by hydrogen peroxide takes a lot of time. Commercially, it is usually best to keep the temperature between 90°C to 100°C. However, one hour of bleaching can be done at 110°C with caution. But when bleaching is done on a machine with pressure, the temperature can be increased from 120°C to 130°C. However, this condition should not be kept for more than 20 minutes. Because cotton loses its strength and is severely damaged.
2. Factors affecting hydrogen peroxide bleaching-Effect of Catalyst:
Hydrogen peroxide destroys when various metals such as copper, zinc, chromium, etc., or metal oxides are used as influencers. Water used in bleaching may contain metals or metal oxides, which accelerate the rate of oxygen generation. The oxygen produced by this reaction has no bleaching ability, so stabilizers are used to stop oxygen generation.
3. Factors affecting hydrogen peroxide bleaching-Effect of stabilizer:
Sodium silicate is used as a stabilizer to protect the bleaching energy from being wasted. Which stops oxygen generation in solution. It does not react with metals or metal oxides and combines with them to form a complex compound, which stops oxygen generation in the solution, meaning that the effector cannot destroy hydrogen peroxide and bleaches properly. It is also used to maintain the pH of the solution.
Below are some examples of stabilizers.
(i) Sodium silicate
(ii) Soya bean protein
(iii) Tri-sodium phosphate
(v) Cotton impurities
(vi) Gelatin etc.
4. Effect of Alkali:
Hydrogen peroxide in acid solutions may not bleach well on cellulose fibers. This is because the release of per hydroxyl ions is very slow. Again, using more alkali breaks down hydrogen peroxide and releases oxygen. So in an alkaline environment hydrogen peroxide acts as an effective bleaching agent. Here the pH of the solution is kept from 9.5 to 10.2.
5. Effect of water:
Some amount of magnesium salt is required for sodium silicate (stabilizer) to act in the bleaching solution. So it is better to use 20 to 60 gallons of water. If mild water is used, 0.1 to 0.2 grams of magnesium sulfate is added.
6. Effect of cotton impurities:
The impurities in cotton help to increase the stability of hydrogen peroxide. As a result hydrogen peroxide is not broken down and bleaching is good. Here impurity acts as a stabilizer. So if there are not many impurities in the cotton, it is better to do scouring. And if scouring is too much, low-density alkali can be used. Or scouring bleaching can be done at the same time.