LAUSR

Abstract Cationized guar gum (CGG) was synthesized by imparting a positive charge to the natural polymer guar gum (GG) and was used as a flocculant for bentonite suspensions. The effect of CGG on bentonite aggregation was evaluated by sedimentation tests. The mechanism of aggregation with CGG is discussed in terms of the aggregate size and the amount of CGG adsorbed in the aggregate. The amenability of bentonite suspensions to filtration using CGG was also investigated. At the optimum CGG concentration, the sedimentation rate increased, the amount of bentonite in the supernatant solution decreased, and the size of the aggregates was the largest under all conditions. The adsorption amount of CGG in the aggregates increased with increasing CGG concentration. The use of low CGG concentrations did not provide sufficient crosslinking between bentonite particles, and the use of high CGG concentrations suppressed bentonite aggregation by causing electrostatic repulsion, because a large amount of CGG covered the bentonite particles; hence there was an optimum CGG concentration for improved bentonite aggregation. When the bentonite suspension was filtered under these optimum conditions for aggregation, the filtration was the fastest, demonstrating that it is possible to apply the filtration method with the use of CGG.