Sorption and Desorption of Crystal Violet and Malachite Green on and from Vermiculite

Department of Chemistry. University of North Bengal, P. O. North Bengal University, Dist. Darjeeling, W. Bengal.

Manuscript received 21 March 1978, revised 30 August 1978, accepted 24 April 1979

Adsorption and desorption studies of crystal violet(CV) and malachite green (MG) have been carried on and from Vermiculite. Of the two dyes the sorption data of crystal violet alone obey the Langmuir equation. The release of the dye ions from their respective clay matrixes by different ions follows the order : Na<NH₄<K <H< Mg <Ca<Ba for crystal violet and Na<NH₄,<K<H<Ca<Ba<Mg for malachite green. The order of the relative binding strength of the dyes for the vermiculite surface, which is in the reverse order of their desorption is : CV> MG. From the sorption data the specific surface area of the mineral has been calculated and the possible modes of orientation of the dye molecules on to the surface have been suggested.