Process for bleaching deinked pulp.

摘要

Bleaching deinked pulps using a combined action of sulphite, that is N2SO3 or NaHSO3, or Na2SO3 and NaHSO3 or SO2 and sodium hydroxide and of a reducing agent which is more electronegative than the sulphite ion, in a medium of initial pH of between 6 and 12. Bleaching of deinked pulps according to the above process followed by a washing to remove the sulphite ion and the said reducing agent from the pulp and by the action of hydrogen peroxide in alkaline aqueous medium.