Potential Malaysia agricultural waste materials for the biosorption of cadmium(II) from aqueous solution

Biosorption of cadmium(II) ions (Cd²⁺) onto Ananas comosus (AC) peel, Parkia speciosa (PS) pods and Psidium guajava (PG) peel were investigated in this study. Batch sorption experiments were performed by investigating the effect of initial pH. It was found that Cd²⁺ uptake was highly dependent on the initial pH and Cd²⁺ removal efficiency was highest for PG peel, followed by AC peel and PS pods. Biosorption experiments were carried out using different initial Cd²⁺ concentration and the experimental data obtained was fitted to both Langmuir and Freundlich isotherms. The experimental data was found to best fit the Langmuir isotherm, and adsorption capacities of 18.21 mg/g (AC peel), 25.64 mg/g (PS pods) and 39.68 mg/g (PG peel) were obtained. Comparison with published adsorption capacities for other low-cost biosorbents indicates that PS pods and PG peel have potential as low-cost biosorbent materials for the removal of Cd²⁺ from aqueous solution.