SIMULTANEOUS ADSORPTION OF POLY(VINYLPYRROLIDONE) AND ANIONIC HYDROCARBON/FLUOROCARBON SURFACTANT FROM THEIR BINARY-MIXTURES ON ALUMINA

The adsorption of lithium dodecyl sulfate (LiDS)/lithium perfluorooctanesulfonate (LiFOS) and poly(vinylpyrrolidone) (PVP) from PVP-LiDS and PVP-LiFOS binary mixed solutions on positively charged alumina has been investigated. The conformation of PVP adsorbed on alumina is also estimated by using ESR. In the PVP-LiDS system, the adsorption of LiDS is shown to be two distinct breakpoints in the presence of PVP, while the adsorption of PVP increases remarkably due to the presence of LiDS at low LiDS concentration, followed by a decrease at high LiDS concentration. It is suggested that this remarkable increase in the adsorption is due to complex formation between PVP and LiDS on the alumina surface. A similar trend is observed in the PVP-LiFOS system. In both PVP-LiDS and PVP-LiFOS systems, the fractions of train segments in the adsorbed PVP steeply increase with the surfactant concentration, and they show a maximum, followed by remaining constant with their segments in trains in spite of the remarkable decrease in the adsorption of PVP. Also, the fraction of train segments in the PVP-LiFOS system is greater than that in the PVP-LiDS system over the whole surfactant concentration region. The results obtained from both dispersion stability and zeta potential correspond to the changes in the adsorption isotherm and values of the fraction of train segments.