Hydrogen peroxide Killer:

It has been observed that some time ( after bleaching with hydrogenperoxide), the presence of residual peroxide in the fabric, effect the dyability of the fabric especially for the dyes which are senstive to oxidation. The presence of residual peroxide may cause shade variation in the dyed fabric. 

In the conventional process, to remove this residual peroxide either fabric is washed several times or treat the fabric with some inorganic reducing agent. Addition of reducing agent is not a right choice because it is difficult to select optimum dosage of reducing agent and if the dosage is high, it may further affect the shade adversely. The several time washing is found to be more useful but it require  a lot of water to wash out residual peroxide. 

To solve the problem of residual hydrogen peroxide, now a days enzyme is used. This enzyme is called peroxidates or catalases. This enzyme act as a reducing agent. The application of this enzyme is ecologically friendly as only oxygen and water are produced. Only small dosage of this enzyme sufficient to reduce residual peroxide.As this process remove/kill peroxide, it is also called peroxide killer. Following process may be used in a jigger:

• Take bleach fabric after application of hydrogen peroxide 
• Wash thoroughly
• Treat this fabric with enzyme (1-2 ml/ltrs) for 5-20 mins at room temperature at neutral pH

Limitations: Following are the limitations:

• At high temperature and pH there is a poor stability of this enzyme
• To prevent the deactivation of enzyme, the bleach bath should be cooled before the addition of enzyme and alkali
• Sometimes cause unacceptable changes in the dyed fabrics