Interactions of vermiculite and cationic dyes
Contribution a l'etude des interactions vermiculite-colorants cationiques
Clay Minerals (December 1978) 13 (4): 411-425
Flakes (1-4 mm (super 2) ) of a water swollen vermiculite-M (M = Na,K) adsorb cationic dyes in aqueous solution by ion exchange. The vermiculite-M selectivity for these cations is very small and their content is less than 7% of the C.E.C. Visible absorption spectra of the vermiculite-(M,dye) obtained and dyes in aqueous solution are compared. Concerning methylene blue, Nil blue A and brilliant green cations, a 25 nm shift of one band is registered. This indicates that cationic dye charge is more localized after adsorption, either on central atoms N and S (methylene blue) or on peripheral atoms N (brilliant green). Infrared spectroscopic studies are consistent with these results. Vermiculite-(M,dye) are not coloured pigments and the use of vermiculite as a dye-support is very limited.