POLYACRYLAMIDE ADSORPTION BEHAVIOR ON NANO-SIZED SILICA PARTICLES AND ITS STABILITY IN AQUEOUS DISPERSIONS

Nano-sized SiO_(2) particles were synthesized by solgel technology.Adsorption behavior of polyacrylamide (PAM) on-to particle surfaces in aqueous suspensions was investigated. Infrared analysis and adsorption experimental results indicate that PAM is absorbed on SiO_(2) particles through hydrogen bonding, and the adsorption behavior is related to PAM concentration, pH values and molecular weight. Adsorption quantity of PAM on the particles increases with the increase of PAM concentration until saturation amount, which increases with the decrease of pH values etc. If other conditions are the same, the higher of PAM in mass, which induces to increase the thickness of adsorbed layer, the higher the amount of PAM adsorption.Surface charge density, diffuse charge density and measured zeta potential of SiO_(2) particles vary distinctly after PAM adsorption. The adsorption of PAM onto surface of nanoparticles can provide a high degree of stabilization and remarkably improve the stability of as-formed suspension against flocculation in water. However, the stability of SiO_(2) suspension will be destroyed when the added amount of PAM exceed the saturation adsorption.