ADSORPTION OF RHODAMINE 6G ON SAPONITE - A COMPARATIVE-STUDY WITH OTHER RHODAMINE 6G-SMECTITE AQUEOUS SUSPENSIONS

Absorption and fluorescence spectroscopies are applied to study the adsorption of rhodamine 6G on saponite in aqueous suspensions. The interpretation of the experimental results suggests that the dye can be adsorbed as the monomeric and the dimeric forms on both the external and the interlamellar surfaces of the clay. A mechanism for the adsorption is proposed on the basis of the evolution of these species with the stirring time and the relative dye/clay concentration. The present results are compared to those previously reported for the adsorption of rhodamine 6G on laponite, montmorillonite of Wyoming, and hectorite in aqueous suspensions, and the effect of the nature of the clay and the particle size is discussed.