Adsorption of malachite green (MG) onto apricot stone activated Carbon (ASAC)-Equilibrium, kinetic and thermodynamic studies

Abstract

The adsorption of malachite green (MG) onto apricot stone activated carbon (ASAC) in a batch adsorber and the effects of contact time, initial pH, agitation speed, adsorbent dosage and initial dye concentration on the MG adsorption by the ASAC have been studied. It was observed that under optimized conditions up to 23.94 mg/g at 25 oC and 88.5 mg/g at 70 oC could be removed from solution. Kinetic parameters; rate constants, equilibrium adsorptin capacities and correlation coefficients, for each kinetic equation were calculated and discussed. It was shown that the adsorption of MG onto ASAC could be described by the pseudo second-order equation. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Temkin, Elovich and Redlich-Peterson equations. Adsorption of MG onto ASAC followed the Langmuir isotherm. The evaluation of thermodynamics parameters such as the negative Gibbs free energy and positive enthalpy change indicated respectively the spontaneous and endothermic nature of the reaction and the chimisorption of the sorption process