Ozone seems to be a good choice in TCF bleaching. However, it is necessary
to study the ozone bleaching optimization due to its poor selectivity. In t
his paper, different reagents have been applied as pretreatment before Z-st
age, to obtain a better selectivity. 8 reagents at different conditions hav
e been employed, therefore 24 pretreatments were carried out. A positive ef
fect was obtained with these pretreatments and the best were chelating and
acid treatments.