IMPROVED OXYGEN DELIGNIFICATION WITH PEROXYACID TREATMENT

Environmental awareness by the pulp and paper industry has resulted in new technologies to reduce pollutants in mill effluents. One technology is oxygen delignification of kraft pulp to reduce pulp lignin content prior to bleaching. Oxygen delignification can reduce pulp lignin content by only 45-50% before strength loss occurs. Improvement of oxygen delignification by pretreatment with peroxymonosulfuric acid might allow more lignin to be removed before pulp strength is adversely affected. Radiata pine kraft-oxygen pulp was treated with 0.6-2.5% peroxymonosulfuric acid prior to a second oxygen stage- Peroxymonosulfuric acid improves overall delignification effectiveness and selectivity. Removal of metal ions was required to maintain adequate selectivity. Despite its current high cost peroxymonosulfuric acid has considerable potential for incorporation into improved non-chlorine bleach systems.