Electroacoustic and calorimetric characterization of polymer adsorption on kaolin

The adsorption of a non-ionic water-soluble polymer, partly hydrolysed polyvinyl acetate (PVOH/Ac), on kaolin has been studied with different methods in this work. The objective was to investigate whether a correlation could be found between the dynamic mobility of kaolin particles and the amount of adsorbed polymer. Additionally, the enthalpy of adsorption is compared with dynamic mobility. It was found, by plotting the adsorbed amount versus the dynamic mobility, that linear correlation could be obtained for a limited concentration range. However, different slopes of the curves indicate that the dynamic mobility cannot directly be converted to the adsorbed amount. This was also confirmed by the enthalpy of adsorption, where quite high exothermic reactions were obtained. The reason was found to be due to relative complex adsorption mechanisms, including adsorption and desorption of ions as well as intercalation of PVOH/Ac into montmorillonite contaminants on the kaolin mineral. Hence, the presence of impurities in the form of other minerals necessitates care when interpreting the data.