PERACID DELIGNIFICATION AND BLEACHING OF CHEMICAL PULP .2. OXIDATION

Peracids have been used as activating agents for lignin before oxygen or a peroxide stage and as brightening agents in later oxidation stage s. In laboratory work, peroxy acid has been tested as a replacement fo r hypochlorite and chlorine dioxide with excellent results in brightne ss and strength retention. Synergistic effects on brightness have been reported for tile use of chlorine dioxide and a small quantity of per acetic acid together in the same bleaching sequence. The use of a pera cid as a final stage in an ECF bleaching sequence to achieve 92 bright ness on a kraft pulp is included in the work presented.