Optimization of adsorption of Cr(VI) from aqueous solution by Leucaena leucocephala seed shell activated carbon using design of experiment

Abstract

Abstract The activated carbon from Leucaena leucocephala seed shell was prepared by chemical activation, characterized and used as adsorbent for the removal of hexavalent chromium [Cr(VI)] from aqueous solution via batch mode adsorption. The variables affecting the adsorption process, initial adsorbate concentration, pH, adsorbent dosage and temperature were optimized using central composite design (CCD) of the response surface methodology (RSM) at fixed contact time of 60 min. Equilibrium adsorption isotherm and kinetic were also studied. The analysis of variance (ANOVA) revealed that all the variables studied had significant effects on the removal efficiency of Cr(VI). The obtained data showed that 71.49 mg/L initial Cr(VI) concentration, 4.22 solution pH, 0.57 g adsorbent dosage and 26.2 °C temperature resulted in 95.62% adsorption. Equilibrium adsorption isotherm and kinetic studies showed that Freundlich isotherm and pseudo-second-order kinetic model fitted well to the experimental data. The activated carbon from Leucaena leucocephala seed shell was found to be efficient for Cr(VI) adsorption.

Keywords

• Activated carbon
• Hexavalent chromium
• Characterization
• Kinetic
• Isotherm