Ozone seems to be a good choice to develop new TCF bleaching sequences. One
objective in the ozone application as a bleaching chemical of pulp is to i
ncrease the selectivity of the process. In this paper, different reagents h
ave been applied as additive in Z-stage, to obtain a better selectivity. 16
reagents at different conditions have been employed. A positive effect was
obtained with these additives and the best was the oxalic acid.