CONTROL OF RETENTION IN PAPER-MAKING BY COLLOID TITRATION AND ZETA-POTENTIAL TECHNIQUES

The concentration influence of some commercial polyethylenimines, used as retention agents, on the retention efficiency during the sheet for mation is studied in this paper The conditions of an industrial wire e nd have been simulated by means of a dynamic jar of exclusive design. Measurements of the zeta potential have been taken to quantify the sur face charge of particles and the colloid titration ratio (quotient bet ween the cationic demand and the anionic demand of pulp slurries) has been evaluated. Both techniques have proved convenient to monitor the retention level; therefore, they are efficient methods to control the retention level in the sheet formation. The univocal relation existing between zeta potential and the logarithm of the colloid titration rat io has been demonstrated. Finally, the variation of the level of turbu lence has proved the importance of the hydrodynamics factors in the re tention.