Removal of Cadmium from Waste-water by Adsorption Using the Husk of Melon (Citrullus lanatus) Seed

Removal of cadmium from simulated wastewater (aqueous solution) using melon husk (an agricultural residue) modified with concentrated sulphuric acid was investigated at room temperature. Adsorption studies were carried out to determine the influence of contact time, initial cadmium ion concentration, adsorbent dosage and particle size on removal efficiency. Removal efficiency was observed to decrease with increasing initial cadmium ion concentration (2-10 mg/L), but increases with decreasing particle size (45-355 μm), and increasing adsorbent dosage (0.02-0.30 g). The data obtained fit into three equilibrium isotherms in the order: Freundlich > Langmuir > Temkin. Modeling of kinetics results showed that the adsorption process was best described by Pseudo-second order model with regression coefficients (r2) higher than 0.998.