Removal of Ni2+, Cu2+, Zn2+, Cd2+and Pb2+ions from aqueous solutions using cashew peduncle bagasse as an eco-friendly biosorbent

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.