Characterisation and adsorption properties of oxalate-loaded hematite composite for Cd(II) and Pb(II) adsorption: Equilibrium models, thermodynamic and kinetic studies

Abstract

In this study, different reagents have been examined to improve the adsorption ability of hematite for the removal of Cd(II) and Pb(II) ions from aqueous solution. The best adsorption result has been obtained using oxalate-loaded hematite. The equilibrium isotherm studies show the best result was attained in the Langmuir model for Pb(II) and Cd(II) ions. Therefore, homogeneous adsorption is dominated, which was emphasised by three-parameter-isotherm models. The experimental data fit well with the pseudo-second-order kinetics. The Pb(II) adsorption was endothermic and spontaneous, but the Cd(II) adsorption was exothermic and unspontaneous.