A study of Adsorption of Crystal Violet from Aqueous Solution on Kaolin

Abstract

This study is concerned with the adsorption of Crystal violet from solution on the surface of
kaolin. UV-spectrophotometric technique has been used to produce quantitative adsorption data
at different conditions of contact time, ionic strength, pH and temperature.
The calculated data were in accordance with Freundlich equation and the adsorption isotherms
are of S-curve type according to Giles classification. The results obtained show that adsorption
process follows the first order rate expression.
The adsorption phenomenon was examined as a function of temperature (20, 30, 55 oC). The
extent of adsorption of Crystal violet on the Kaolin was found to increase with
increasing temperature (endothermic process). The basic thermodynamic functions have also
been calculated.
The amount of dye adsorbed on the clay at different pH values showed an increase in the
following order pH 7< 8.1<10.5<11.9.
The adsorption process is affected by the electrolyte concentration. The results indicated an
decrease in adsorption of crystal violet in the presence of sodium hydrochloride.