Single and mixed adsorption of Cd(II) and Cr(VI) onto citrate-coated magnetite nanoparticles

In the present work, we compared single and mixed adsorption of Cd(II) and Cr(VI) onto co-precipitation synthesized citrate-coated magnetite nanoparticles (NPs). Single kinetic studies revealed Cr(VI) to be better adsorbed than Cd(II). Otherwise, Cd(II) adsorption ratio was improved with Cr(VI) in the binary mixture. Single and mixed adsorption data followed in good agreement the pseudo-second-order kinetic model, with higher initial adsorption rate and rate constant values for Cr(VI). Equilibrium data from single Cd(II) and Cr(VI) adsorption only fitted concordantly the Freundlich isotherm model. The sorption capacity of magnetite NPs as function of initial metal concentrations was found to be 3mg/g for Cd(II) and 4.65mg/g for Cr(VI).