Synthesis and Characterization of Activated Carbon from Mahogany Fruit Shell (Khaya senegalensis) Impregnated with TiO2 Used in the Adsorption of Cadmium and Arsenic

Abstract

In this Study, low-cost activated carbon impregnated with TiO2 (Ac/ TiO2) was prepared from mahogany fruit shell (Khaya senegalensis) by chemical activation using phosphoric acid, H3PO4. The resulting product was evaluated for the removal of Arsenic and Cadmium ions from aqueous solutions. The prepared activated carbon was characterized using SEM, FTIR and XRD. Operational parameters such as initial concentration, adsorbent dose, contact time, effects of pH and temperature were studied in a batch system. It was found that the percentage removal for arsenic and cadmium were around 98 and 97% respectively. Equilibrium of the adsorption processes were obtained by testing the adsorption data using two different isotherm models: Langmuir and Freundlich. The adsorption of arsenic fitted well with Freundlich with R2 value of 0.9106. The kinetic of adsorption process was tested through pseudo first order and pseudo second order models. The Pseudo Second Order Kinetic Model provides the best correlation for the experimental data of both the two metals studied. Thermodynamics parameters, such as ΔGo, ΔHo and ΔS0 were also calculated. This result shows that the process of adsorption for arsenic was spontaneous and exothermic, while that of cadmium was spontaneous and endothermic.