Pate of Chelating Agents Used in he Pulp adn paper Industry

摘要

The use of chelating agents in the Scandinavian pulp and paper industry has drastically increased during the 1990s due to the eliminatin of the use of elemental chlorine in pulp bleaching nad the implementation of bleaching sequences utilizing oxygen-based chemicals and chlorine dioxide. The decomposition of hydrogen peroxide, oxygen, and ozone is accelerated by transition metal ions such as manganese, iron, and copper. Thus, the optimized control of metal ions in pulp through chelating agents has become an important issue. Recent developemnts in analytical techniques have enabled the accurate determamination of chelating agents such as diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid both in bleach liquors and in pulps. This paper reports results on the total mass balances of chelating agents during modern ozone and hydrogen peroxide bleaching processes. World consumption of chelating agents nad their behavior in a mill's effluent treatment system and in recipients are also briefly discussed.