How to test peroxide stabilizers?

What is a peroxide Stabilizer?

To know what is a peroxide stabilizer we should know a little more about what is peroxide itself and what are its behaviors?

Hydrogen peroxide is the most commonly used bleaching agent for natural vegetable and animal fibers. It is necessary to activate the hydrogen peroxide for effective bleaching. Stabilization of the bleaching solution is also essential to minimize the loss of active oxygen. Hydrogen peroxide (can be considered as a very weak acid) dissociates in aqueous solution only to a small extent. H2O2 = H+ + HO2.

In pure water, particularly in acid solutions hydrogen peroxide exists mostly in un-dissociated form and is very stable. For the same reason, commercial concentrated products are maintained acidic.

Since hydrogen peroxide is very active in alkaline medium and dissociates in to nascent oxygen and water in large extent, even before it bleaches the fiber, a catalyst is necessary to reduce the dissociation level. These catalysts are called Peroxide Stabilizers.

Generally inorganic salts like MgCl2, CaCl2, MgSO4 etc and some silicates are considered to be best stabilizers for peroxide bleaching.

But these salts after bleaching leave a harsh feel to the fabric due to the deposition of the hydroxides of these salts and hence are not suitable for peroxide bleaching.

Now there are many organic peroxide stabilizers available in the market. Generally the quality of these products vary from manufacturer to manufacturer. One can ascertain its quality only by conducting actual bleaching process using these materials and assessing the whiteness ../default of the bleached material, its feel and other physical properties.

However the following tests may be used to keep record of a particular product. The batch to bath variation of from the same manufacturer's product can be monitored.

Test Methods for quality and consistency:

Specific gravity:
Accurately weigh 10 ml of the peroxide stabilizer. Specific gravity = Volume/Mass. Note down the value and do this test whenever your receive a new consignment and compare against the first supply.

Solid content:
Refer procedure of wetting agent.

pH of 1% solution:
Dissolve 1 gram of the peroxide stabilizer in 100 ml of distilled water and check the pH.

Ionic Nature:
Check the stability of this product against the addition of acid and alkali under processing temperature of 70C.

Analytical Method:
You can test the concentration of peroxide in a bleaching for every 10 minutes and plot a graph. Compare the same against the competitor's product.