POM-assisted electrochemical delignification and bleaching of chemical pulp

A polyoxometalate-catalyzed electrochemical process has shown good selectivity in delignifying pulp. This breakthrough in redox catalysis shows promise for the development of a new environmentally benign technology for pulp bleaching. The electrochemical process, applied with a mildly alkaline electrolyte solution containing trace amounts of a vanadium-based polyoxometalate, K 5 [SiVW 11 O 40 ], decreased the kappa number of a softwood Kraft pulp by about 40% without significant change in the viscosity of the pulp. In a similar electrochemical process, a softwood semi-bleached Kraft pulp was further bleached to a high brightness pulp, above 85% ISO, by electrolysing a borax-based electrolyte activated with tetraacetylethylenediamine in a pulp suspension.