Adsorption Effects on the Rheological Properties of Aqueous Alumina Suspensions with Polyelectrolyte

Abstract

The influence of adsorption coverage and free polymer on the rheological properties of aqueous alumina suspensions with polyelectrolyte was studied. The flow curves of the suspensions followed the Casson model very well in the observed range of shear rate. The Casson yield value, τ c , was used to evaluate the stability. The coverage exerted a profound influence on the rheological properties by affecting the interaction between particles. The zeta potential increased and the value of τ c decreased as the coverage increased. The free polymer could cause weak flocculation as its concentration was increased to a certain level. The opposite effects of the adsorbed polymer and free polymer on stability resulted in the presence of optimum coverage for stabilization. The concentration of free polymer increased rapidly as the adsorption coverage approached the saturation limit, and then the free polymer started to dominate the stability. Stabilization could be achieved at a condition of unsaturated adsorption and was related to the non‐high‐affinity adsorption at alkaline pH (9.2). The impact of adsorption affinity on stability was discussed.