Keywords: coconut copra meal, cadmium ions, pseudo-second-order, kinetics, heavy metals, metal removal, sorption, biosorption, isotherms, wastewater treatment, water pollution
Kinetic biosorption study of cadmium onto coconut copra meal as biosorbent
The sorption of cadmium ions on an agricultural by-product, coconut copra meal, was investigated. A batch sorption model, based on the assumption of the pseudo-second-order mechanism, was applied to predict the rate constant of sorption, the equilibrium sorption capacity and the initial sorption rate with the effect of initial cadmium concentration and temperature. Activation energy of sorption was determined based on the pseudo-secondorder rate constants. In addition, the experimental results were analysed by pseudo-Langmuir, pseudo-Freundlich and pseudo-Redlich-Peterson isotherms based on pseudo-second order kinetic expression constant. Both pseudo- Langmuir and pseudo-Redlich-Peterson isotherms were found to represent the measured sorption data well. According to the evaluation using the pseudo-Langmuir equation, the monolayer sorption capacity was obtained to be 2.59 mg/g.