Colloidal and Sedimentation Behavior of Kaolinite Suspension in Presence of Non-Ionic Polyacrylamide (PAM)

Abstract

Colloidal behavior of kaolinite particles in water was investigated in this manuscript, without and with the addition of a polymer flocculant (non-anionic polyacrylamide (PAM)), using diverse imaging techniques in addition to LUMisizer. The addition of PAM was found to be causing the formation of bridges among particles thus increasing their settling rates to the bottom of the container. To assess the size of flocs and the potential morphology of PAM around particles and their clusters, the state of flocs formation and polymer distribution was analyzed through various microscopical techniques, namely scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM results revealed that, in the absence of PAM, the floc structure of the sediment was loose and irregularly distributed, while the presence of PAM made the sediment structures greatly denser. Later, using LUMisizer, dynamic light scattering (DLS) and the zeta potential of kaolinite, sedimentation, and colloidal behavior of suspension came under scrutiny. Using LUMisizer, the maximum packing and settling rates of the particles were experimentally obtained as roughly 44 vol%; settling rates were estimated in 63–352 µm/s when centrifugal force varied and, using maximum packing values, compressive yield was estimated to vary between 48–94 kPa. The results of this study are instructive in choosing appropriate polymers and operating conditions to settle clay minerals in tailing ponds. Additionally, the maximum packing of kaolinite particles was simulated with spherical particles with varied polydispersity to connect DLS data to the maximum packing values obtained using LUMisizer; the little discrepancy between simulation and experimental values was found to be encouraging.