Closed-Mill Delignification by Design using polyoxometalates

摘要

Polyoxometalates are a class of delignification agents that promise to provide the basis for a new closed-mill bleaching technology. The results presented here are based on the use of Na sub 6SiV sub 2W sub 10O sub 40, is effective in reducign the Kappa number of softwood Kraft pulp from 30 to Below 10 with minimal loss in viscosity. A critical part of a viable POM process is the elimination of the organic lignin and carbohydrate-derived fragments dissovled during the delignifiction. To simulate a closed process, a series of pulp samples were delignified with the same POM liquor. Before each pulp sample was treated, the liquor was oxidized to regenerate the POM nad remove a large portion of the organic material dissolved during the previous delignification ste. By collecting and reusing the wash water during this set of experiments, we showed that a steady-state carbon load will be acheived and that the proposed industrial porcess is feasible. The rate of the wet oxidation of organic material was similar to the rate observed for acteate oxidation.