Dye stripping by oxygen in secondary fiber recovery
AssigneeAir Products and Chemicals, Inc.
InventorsRonald C. Naddeo, Konstantinos Hristofas, Vincent L. Magnotta
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Abstract
Color is removed from secondary pulps with non-chlorine based bleaching agents in treating sequences using oxygen with combinations of peroxide, ozone, and/or hydrosulfite at/controlled pH conditions. Acid treatment prior to bleaching steps improves color removal and protects fibers from damage at more severe bleaching conditions.
Claims4
A method for the preparation of a secondary pulp from waste paper material containing color bodies including dye comprising comminuting said waste paper material with water to form a pulp comprising cellulosic fibers and said dye while controlling the pH during said comminuting at values below 8 or above 10, and contacting said pulp with an oxygen-containing gas in one or more subsequent stages wherein said oxygen reacts with said dye to yield decolorized pulp.
Dependencies are inferred from the claim text.