Applications of capillary ion electrophoresis in the pulp and paper industry

Abstract

Alkaline (kraft) pulping of wood accounts for more than 60% of paper production. Anions critical to the performance of the kraft pulping process are presently determined by wet chemical methods and more recently by ion chromatography. Chemical recovery and liquor regeneration efficiencies are evaluated by monitoring these ions: Cl −, S 2O 2− 3, SO −2 3, SO −2 4, S 2−, OH −, and CO 2− 3, Na + and K +. Capillary ion electrophoresis is a novel analytical technique that is optimized for the rapid monitoring of charged species. The technique is applied for the first time on kraft process streams using indirect UV detection at 254 nm and 214 nm to monitor the charged species. The results are used to evaluate important process variables such as sulfidity (white liquor), reduction efficiency (recovery furnace performance), and causticization efficiency (slaker performance). This paper presents results obtained by off-line monitoring of ions found in the white, black and green liquors from kraft mills. The potential of capillary ion electrophoresis as a cost effective technique for rapid process processing of kraft pulping liquors is suggested.