Investigation of adsorption and ultrasound assisted desorption of lead (II) and copper (II) on local bentonite: A modelling study

This paper assesses the potential of the natural bentonite for the adsorption and ultrasonic desorption of toxic heavy metal cations (i.e., Pb(II) and Cu(II)). Adsorption and desorption processes have been modelled with the aid of a factorial design-approach. The ability of untreated bentonite to remove Pb(II) and Cu(II) from aqueous and acidic solutions at different pH values has been studied for different metal concentrations by varying the amount of adsorbent, temperature. stirring speed and contact time. The same factors, except stirring speed and metal concentration, were applied in desorption study. Ultrasound power was used for desorption instead of stirring speed. A flame atomic absorption spectrometer was used for measuring the Pb (II) and Cu(II) concentration before and after both experimental studies. The results show that the highest adsorption for both Pb and Cu were obtained in excess of 99 % and the highest desorption for Pb and Cu obtained were 28.71% and 66.61% respectively. It is believed that the models obtained for adsorption and desorption may provide a background for detailed mechanisms searches, pilot and industrial scale applications. (C) 2010 Elsevier B.V. All rights reserved.