SILICA SURFACE-CHEMISTRY AT ELEVATED-TEMPERATURES

Potentiometric titrations of SiO2 surfaces at 25 and 60-degrees-C indicate that SiO2 surface chemistry is sensitive to temperature. The number of negatively charged surface sites becomes more pH dependent at T > 25-degrees-C. Metal binding constants for Cd++ and Pb++, calculated with a constant capacitance model, increase by between 0.3 and 2 orders of magnitude between 25-degrees-C and 60-degrees-C. This parallels temperature-dependent changes in the association constants for the respective metal hydrolysis constants.