Enhanced bleaching of sulfite pulp and mechanical pulp with hydrogen peroxide

摘要

This paper introduces some improved methods for bleaching sulfite pulp and mechanical pulp with hydrogen peroxide, which involve the use of an additive or activator in conventional peroxide bleaching systems. It has been found in this investigation that a commercially available product, Prestogen W Liquid (BASF), is an effective additive for improving the bleaching of both sulfite pulp and mechanical pulp, but it does not seem to have a significant effect on kraft pulp bleaching. This product, containing an aliphatic dicarboxylic acid and chelating agents, has previously been used in the textile industry for enhancing the peroxide bleaching of wool under acidic to mildly alkali pH conditions, but it has not been identified as beneficial for use in paper pulp bleaching until now. 1,1-diethylurea (1,1-DEU), which is known to be an excellent peroxide activator for kraft pulp bleaching, has also been evaluated for bleaching of sulfite pulp and mechanical pulp. It has been found that 1,1-DEU has a positive effect on sulfite pulp bleaching, and it may also be used in combination with Prestogen W to further improve the brightness of sulphite pulp. However, 1,1-DEU has little effect on mechanical pulp bleaching.