Interaction between polyvinylpyrrolidone and sodium dodecyl sulfate at solid/liquid interface

Abstract

The adsorption of sodium dodecyl sulfate and polyvinylpyrrolidone from their mixed solutions onto Fe 2O 3 and carbon black has been investigated. On the surface of Fe 2O 3, the adsorption of SDS is shown to be almost unaltered by the presence of PVP, while the adsorption of PVP increases markedly due to the presence of SDS at low SDS concentration, followed by a dramatic decrease at high SDS concentration. It is suggested that this is due to complex formation between SDS and PVP: surface complexes at low SDS concentration and solution complexes at high SDS concentration. The interactions between PVP and SDS both on Fe 2O 3 and in solution are reinforced as the pH of solution decreases. On the surface of carbon black, the adsorption of PVP and SDS is shown to be merely competitive. The obvious difference between the adsorption manners of PVP SDS on Fe 2O 3 and on carbon black was discussed in terms of the configuration of adsorbed SDS molecules and the polarity of the solid surfaces.