In-Situ Investigation of Adsorbed Surfactants and Polymers on Solids in Solution

Adsorption of monomeric and polymeric organic compounds onto solids is crucial in regulating such processes as flotation. flocculation and stabilization of minerals as well as other solids. The microstructure of the adsorbed species is of prime concern in understanding the complexities of the resultant processes. In this paper, we summarize the results of our recent investigation on the alumina-sodium dodecyl sulfate system by specially developed techniques based on time-resolved resonance Raman. electron spin resonance and luminescence spectroscopies to supplement the results from measurements of bulk properties such as adsorption density. zeta potential and hydrophobicity. Evidence is presented to substantiate the reverse orientation model. Furthermore. the implications of pH dependent conformational changes of polyelectrolytes in solution and in the adsorbed state are brought forth from fluorescence studies with pyrene-tagged polymers. and a model for the polymer conformational features is presented supported by flocculation response