Chun Wai Cheung

Sorption Kinetic Analysis for the Removal of Cadmium Ions from Effluents Using Bone Char

The adsorption of cadmium ions onto bone char has been studied using a batch adsorber. The experimental data was analyzed using four sorption kinetic models--the pseudo-first order, the Ritchie second order, the modified second order and the Elovich equations--to determine the best-fit equation for the sorption of metal ions onto bone char. The best-fit equation was identified using the sum of the errors squared (SSE). Finally, equilibrium studies were used to evaluate the sorption capacity of bone char for cadmium ions and experimental results showed this to be 0.57 mmol g-1 at an equilibrium solution concentration of 3.0 mmol dm-3. Since the sorption capacity is relatively high, bone char can be considered as a suitable sorbent for the adsorption of cadmium in wastewater treatment systems.

Sorption kinetics for the removal of copper and zinc from effluents using bone char

Abstract The removal of copper and zinc ions from aqueous effluents by bone char has been studied in single component sorption systems. The sorption capacity of bone char for copper and zinc is 0.75 and 0.53 mmol per g bone char, respectively. The values indicate that bone char is a suitable sorbent for the two metal ions. The equilibrium isotherms are best described by a Langmuir–Freundlich (L–F) type isotherm equation. The kinetics of sorption of the two metal ions have been analyzed by two kinetic models, namely, the Lagergren pseudo first-order model and the Elovich kinetic model. Kinetic analysis of the two models has been carried out for system variables — initial metal ion concentration and mass of bone char. The rate constants for the two models have been determined and the correlation coefficients have been calculated in order to assess which model provides the best fit predicted data with experimental results. The Elovich equation provides the best fit to experimental data.

Elovich equation and modified second-order equation for sorption of cadmium ions onto bone char

The removal of cadmium ions from water by sorption onto bone char has been studied. Bone char, traditionally used for colour removal in sugar refining, is produced by the carbonisation of animal bone. Batch experiments were carried out to study the effects of initial cadmium ion concentration and bone char mass on the sorption rate. The experimental contact data were analysed using the Elovich model, previously used to describe the kinetics of gas adsorption on solids, and the Ritchie model, a modified second-order kinetics equation. Initial analysis of the data, using the Ritchie model, was poor and therefore a modification was incorporated to make the Ritchie model predictions correlate the experimental data more accurately. Both the Elovich and modified Ritchie equations accurately predict the sorption capacity of cadmium on bone char, however, the sorption kinetics, derived from the differential forms of the two equations, were correlated better using the Elovich equation. © 2000 Society of Chemical Industry