CONTROLS ON POLYACRYLAMIDE ADSORPTION TO QUARTZ, KAOLINITE, AND FELDSPAR

Potentiometric titrations of quartz, kaolinite, feldspar, and partiall y hydrolysed polyacrylamide (HPAM), and sorption measurements of HPAM on the minerals, allows identification of the general mechanisms of po lyacrylamide adsorption to aluminosilicates and quartz. Adsorption was monitor ed at the mineral solution interface by way of X-ray photoele ctron spectroscopy (XPS). XPS spectra of the unreacted minerals show b ands in the Ols, Si2p, Al2p, and Cls regions, Additional peaks are a o bserved in the Cls and N1s regions after treatment with polyacrylamide and the latter is used in this study to monitor polymer adsorption. N 1s peak intensities increase with polymer concentration to a maximum c orresponding to surface site saturation. At a fixed polymer concentrat ion, adsorption varies with pH-dependent surface charge. The adsorptio n mechanism changes with pH, reflecting variation in the pH-dependent concentrations of ionizable groups on polyacrylamide and at aluminosil icate surfaces, and the extent of hydrogen-bonding between uncharged m ineral surface sites and polymer amide groups. Copyright (C) 1997 Else vier Science Ltd.