Spectroscopy of rhodamine 6G adsorbed on sepiolite aqueous suspensions

Electronic absorption and fluorescence spectroscopies are applied to study the adsorption of rhodamine 6G dye on sepiolite particles in aqueous suspensions. The adsorption of the dye on the clay is performed for several loadings and stirring times after samples preparation. The monomer of the dye is adsorbed on the external surface of the clay for low loadings and short stirring times. The flocculation of the samples is observed for high relative dye/clay concentration samples. For intermediate loadings, the ageing of the samples leads to the presence of dye molecules in the interspace of clay aggregates, which are identified with the preflocculation state of the samples. (C) 1997 Academic Press.