Heavy metal removal by agricultural waste : adsorption of Cd(ll) by oil palm fiber and coconut coir / Nor Aimi Abdul Wahab and Norain Isa

This study deals with the adsorption of Cd(ll) from aqueous solution by using two agricultural waste without modification; unmodified oil palm fiber (UMOPF) and unmodified coconut coir (UMCC). Batch studies were performed to evaluate the influences of various experimental parameters like pH, initial Cd(ll) concentration and contact time. The adsorption efficiencies were found to be pH dependent, increasing with increasing pH value. The highest removal was observed at pH 7. The uptake of Cd(ll) occurred rapidly and the equilibrium was attained around 60 minutes for both adsorbent. The suitability of the Freundlich and Langmuir isotherm model to the equilibrium data were investigated for each adsorbent. The result obtained in this study showed good fit to Langmuir for UMOPF and Freundlich for UMCC. Two simplified kinetic models were tested to investigate the adsorption mechanism. The kinetics of Cd(ll) adsorption on UMOPF and UMCC were found to follow the pseudo-second order model. A comparative study with the removal by activated carbon (AC) were also investigated. Comparison of the removal of Cd(ll) by these adsorbent with respect to that by AC showed that at low concentration, both UMOPF and UMCC exhibited almost the same performance as AC with removal of almost 99%. The result suggest that UMOPF and UMCC has high possibility to be used as effective adsorbent for Cd(ll) removal.