Competition between kaolinite flocculation and stabilization in divalent cation solutions dosed with anionic polyacrylamides.

摘要: Divalent cations have been reported to develop bridges between anionic polyelectrolytes and negatively-charged colloidal particles, thereby enhancing particle flocculation. However, results from this study of kaolinite suspensions dosed with various polyacrylamides (PAMs) reveal that Ca(2+) Mg(2+) can lead colloid stabilization under some conditions. To explain the opposite but coexisting processes flocculation divalent cations, a conceptual model (1) particle-binding cationic PAM molecules particles (2) polymer-binding is proposed. The enhanced aggregated in large, easily-settleable flocs whereas increased steric by developing polymer layers covering surface. Both coexist PAM- kaolinite-containing thus induce counteracting stabilization. Therefore, cation-enriched aqueous solutions sometimes due bridges.