JOURNAL OF ENVIRONMENT AND HUMAN Adsorption Kinetics for Malachite Green Removal from Aqueous Solution Using

In this work, the isotherms, kinetics and thermodynamics of the adsorption of malachite green dye from aqueous solution using local clay from Nigeria was investigated. The clay was prepared for adsorption by chemical activation with sulphuric acid and hydrochloric acid. The clay was characterized for its physical properties and chemical compositions. The effects of temperature, pH, dosage and concentration on the adsorption mechanism were studied. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were investigated and it was seen that the adsorption most fitted the Freundlich isotherm. The values of the separation factor RL was found to be less than 1.0 for the two activated clays indicating favorable adsorption process. The kinetic study showed that Pseudo second-order model best described the kinetics of the adsorption. A maximum adsorption capacity (qe) of 32.147 mg/g and 32.633 mg/g was obtained for the clay activated with sulphuric acid and hydrochloric acid respectively. The thermodynamics factors were also evaluated. The entropy changes (DS) and enthalpy change (DH) were positive suggesting that the adsorption process increases in entropy and is endothermic in nature respectively. The negative DG value confirms the spontaneity of the process. Keywords