Hydrophilic activators, bleaches

Bleaching of wool is necessary for the enhancement of whiteness and lustre. Using proteolytic enzymes alone [99] or in combination with peroxide [100], the degree of whiteness and hydrophilicity of the fibres are increased, comjjared with the oxidative treatment alone [99]. Serine protease stable to hydrogen peroxide is active in an alkaline medium and its activity increases with increasing peroxide level [94]. Higher whiteness index is caused by the decolourising action of the enzyme on natural colorants present in the wool fibre [100]. 

Hydrophilic peracids with less than four carbon atoms are effective bleaches, oxidizers, and disinfectants. The most important is peroxyacetic acid, which is often used in equilibrium mixture with acetic acid and hydrogen peroxide as a 5,10, or 15% active solution. Its characteristic odor and safety aspects, however, prevent its widespread use in homecare applications. 

FIGURE 16.5 Hydrophilic bleach activators. TAGU = tetraacetyl glycolurils DADHT = diacetyl dioxo-hexahydrotriazine PAG = pentaacetyl glucose. 

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