Abstract
In this study, the adsorption efficiency of cashew peduncle bagasse (CPB) is reported for the removal of single-(mono-) and multi-metal ions (Cd2+; Cu2+; Ni2+; Pb2+; and Zn2+) from synthetic and natural effluents using fixed-bed columns. The percentage of saturation realised in this study using a mono-elemental system was as follows: Pb2+ > Cd2+ > Zn2+ > Ni2+ > Cu2+. The metal ion recovery rate was determined by column elution; we demonstrated 100% metal ion recovery using 40 mL of HCl or HNO3 (0.1 mol L−1) as the eluent, with the exception of Pb2+. The adsorbent regeneration process decreased the removal efficiencies to 90% (Pb2+), 44% (Cu2+), 99% (Ni2+), 81% (Cd2+) and 74% (Zn2+) after the first cycle. The breakthrough curves and kinetic adsorption factors controlling the adsorption process were also studied. The Thomas model has produced the best fit with the experimental data.
Acknowledgements
The authors would like to thank FUNCAP (Fundação Cearense de Pesquisa,) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico. We also thank the Laboratory of Trace Analysis and Laboratory of Water Analysis of the Federal University of Ceará, as well as EMBRAPA-Tropical Agro-industry, CE, Brazil (EMBRAPA/CE) for samples of cashew peduncle bagasse.