Improved peroxide bleaching of deinked ONP with zeolite based replacement chemicals

The use of environmentally acceptable chemical chelating agents and their pretreatment processes for deinked newsprint pulp are reviewed. A thermal pretreatment is sufficient to achieve the required bleachability without chemical pretreatment. Synergistic chelation properties were induced in zeolites by combining them with organic polyacid salts in a deinked mechanical pulp (DIP) pretreatment process which reduced the quantity of silicate stabilizer required for bleaching. Oxidative bleaching properties in zeolites were introduced by organic hydroperoxide support Thus t-butyl hydroperoxide supported zeolite gave a moderate improvement in brightness of DIP is used together with hydrogen peroxide.