The structure of electrical double layer of silica in the presence of polyvinyl alcohol (PVA) at different temperatures

摘要

The effect of polyvinyl alcohol (PVA) adsorption on the structure of the electrical double layer of silica (SiO_2) in the temperature range 15-35 ℃ was studied. The potentiometric titrations were applied in the experiments, which enable determination of the surface charge density of silica systems without and with adsorbed polymer. The preferential adsorption of acetate groups of not fully hydrolysed PVA chains (degree of hydrolysis 97.5%) through hydrogen bridges is mainly responsible for bonding process of polymer with adsorbent surface. The obtained results indicate that temperature increase causes more stretched conformation of adsorbed macromolecules and the greater number of acetate groups can be adsorbed on the solid surface. It leads to changes in structure of polymer adsorption layer on the solid surface and the increase of the SiO_2 surface charge with the rising temperature was observed.