The effects of PAM on the gravity-induced flocculation of colloidal particles in binary suspensions

The effects of polyacrylamides (PAM) at different ionic strengths on the gravity-induced heteroflocculation behavior of binary suspensions are investigated based on the turbidity measurement method in the present paper. For the binary suspensions composed of two different-sized latexes, it is found that the stability ratios of the suspensions decrease with the increase of either the PAM or the electrolyte concentration, and with the increase of the size differences between two latex components of the binary suspension. From the pictures of scanning electron microscopy, it is also interesting to find that, even when both latexes are negatively charged, the small latexes can still be adsorbed at the interparticle regions between two large latexes through the bridge formed by PAM between the small and the large latexes.