Investigation of a basic dye removal from aqueous solution onto chemically modified Unye bentonite

The adsorption behavior of crystal violet (CV(+)) from aqueous solution onto magnesium-oxide coated bentonite (MCB) sample was investigated as a function of parameters such as initial CV(+) concentration, contact time and temperature. The Langmuir, and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir monolayer adsorption capacity of MCB were estimated as 496 mg/g. The pseudo-first-order, pseudo-second-order kinetic and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated. The values of the energy (E(a)), enthalpy (Delta H(not equal)) and entropy of activation (Delta S(not equal)) were 56.45 kJ/mol, 53.90 kJ/mol and -117.26 J/mol K, respectively, at pH 6.5. (C) 2008 Elsevier B.V. All rights reserved.