Size distribution analysis of microstickies treated by enzyme mixtures in papermaking whitewater

Abstract

Microstickies present a formidable challenge for papermakers. Many strategies have been explored to control them. Enzyme treatment is a promising technology, but the mechanism of its action has not been determined, thus inhibiting further application of this new technology. This study investigated characteristics and size distributions of microstickies treated by esterase-cellulase mixtures. Determination of particle size and number was accomplished using a modified flow cytometer, which combined streaming capillary flow, laser-based particle size analysis and fluorescent dye tracing. The results showed that treatment of samples with enzyme mixtures induced size reduction of the larger microstickies. This effect was most dramatic for 1:1 ratios of esterase to cellulase. The treated particles were more stable than untreated ones. The smaller microstickies treated with some ratios of esterase and cellulase tended to aggregate over time. The behaviors of microstickies treated by enzyme mixtures were only slightly affected by temperature and shearing action. The surface physicochemical characteristics of these particles indicated that changes of these basic properties affected the whole whitewater system and resulted in a new equilibrium among all the particles.