ADSORPTION OF POLYACRYLAMIDES ON SILICEOUS MINERALS

The adsorption of high molecular weight neutral and anionic polyacrylamides from aqueous solutions containing sodium chloride on siliceous minerals such as sand and oxidized silicon carbide particles has been studied. All experiments were conducted in batch on powdered minerals. The conditions under which mechanical degradation of polymers may occur during batch experiments are analyzed. Moreover, polymer adsorption is limited to the accessible surface, which depends on macromolecule size, and thus specific surfaces determined by BET measurements are not relevant for polymer adsorption. The modifications in structure and surface charge induced by thermal treatment of silicon carbide particles drastically alters the adsorption properties of both neutral and charged polyacrylamides. Changes in pH and salinity have significant effects on the amount of charged polymer adsorbed onto all siliceous minerals. These effects are explained in terms of polymer/solvent/surface affinity changes and surface and polymer charge. © 1990.