(100b) Multi Component Adsorption of Heavy Metals Using Sodium Iminodiacetate Resin

Koong, L. F., The Hong Kong University of Science and Technology
McKay, G., Hong Kong University of Science and Technology
Barford, J., Hong Kong University of Science and Technology

Acid leaching and bioleaching are simple technologies in extracting the metals from solid waste. However, a mixture of metal species are leached out which can complicate downstream recovery. Separating these metals using selective adsorption has a good advantage as the metals can be recoverd individually at low concentration and reconcentrated at higher purity for reuse. A commercially available sodium iminodiacetate resin was used to investigate the multicomponent adsorption studies of Copper, Nickel and Zinc Sulfate which are commonly found in bioleaching solution of printed circuit boards. Single, binary and ternary components system were carried out to study the effect of competing metals on selectivity and adsorption capacities. The resin has adsorption capacity around 2mmol/g and has a selecitivty in the order of Cu>Ni>Zn and Cu could be separated completely from the ternary component system but not the remaining Ni and Zn. Ni however is adsorbed at 50% higher capacity than Zn. pH was found to have no effect on the order of selectivity of metal. The effect of metal ratio on selectivity was also carried out and it was found that at lower metal ratio of the dominant metal, the other competing metal is also adsorbed as there are vacant sites available for other metal uptake, indicating displacement mechanism which contributes to selectivity. Single component adsorption data are modelled with Langmuir, Freundlich, Redlich Peterson and SIPS. Binary component adsorption data are modelled with Extended Langmuir,Extended Freundlich, Extended Langmuir-Freundlich,Extended Redlich-Peterson, IAST-Langmuir and IAST-Langmuir-Freundlich. The ternary component adsorption data is also modelled with a modified Freundlich.