IMPROVED PEROXIDE BLEACHING OF DEINKED ONP WITH ZEOLITE BASED REPLACEMENT CHEMICALS

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