Kinetics, Isothermal and Thermodynamic Modelling Studies of Hexavalent Chromium Ions Adsorption from Simulated Wastewater onto Parkia biglobosa-Sawdust Derived Acid-Steam Activated Carbon

Abstract

The adsorption potential of activated Parkia biglobosa-sawdust carbon for hexavalent chromium ions removal from its wastewater at various operating variables of contact time, initial hexavalent chromium ions concentration, adsorbent particle size and temperature was investigated and evaluated under batch operation mode. Results indicated the impact of operating variables on the adsorption of hexavalent chromium ions. The adsorption process followed Lagergren pseudo first-order kinetics. The adsorption mechanism was film diffusion-controlled. Freundlich and Harkins-Jura isotherm models provided the best correlation (R² = 0.96) of the equilibrium adsorption data. The maximum monolayer adsorption capacity () was found to be 17.54 mg/g. Calculated thermodynamic quantities were evaluated. It was found that the adsorption process was spontaneous, feasible, and endothermic and predominantly of physisorption process with little chemisorption. Therefore, acid-steam activated carbon produced from Parkia biglobosa wood sawdust has potential for application as an effective adsorbent for hexavalent chromium removal from wastewaters