Adsorptive removal of lead ion from aqueous solution by activated carbon/iron oxide magnetic composite

Abstract

The adsorption features of activated carbon and the magnetic properties of iron oxides have been combined in a composite to produce magnetic adsorbents. These magnetic particles can be used as adsorbent for the removal of heavy metals such as lead from aqueous solution and can subsequently be removed from the medium by a simple magnetic procedure. The prepared samples have been characterized by SEM, N₂ adsorption–desorption and powder XRD. The results show that the presence of iron oxides caused a decrease in the surface area and microporous volume of the activated carbon. The effects of initial solution pH, contact time, adsorbent dosage and initial concentration of lead ion on the adsorption behaviour of lead ion onto the synthetic magnetic adsorbent have been investigated. Kinetic studies show that the overall adsorption rate of lead ion is illustrated well by the pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the lead ion adsorption data is tested. The results show that the Langmuir equation gives a better fit than Freundlich equation to the adsorption isotherms. Moreover, the prepared composite exhibits paramagnetic behaviours and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by heavy metal pollutants.