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. |
