KINETICS AND EQUILIBRIUM STUDIES FOR THE ADSORPTION OF LEAD (II) AND CHROMIUM (VI) IONS FROM AQUEOUS SOLUTION USING PUMICE

Abstract

The main target of this study was to investigate the efficiency of pumice on the removal of Cr(VI) and Pb(II) ions from aqueous solution. The experimental procedure for the adsorptive removal of the two cations was carried out in batch mode of adsorption and the influence of certain parameters such as particle size, adsorbent dose; pH, contact time and initial metal ion concentration were also optimized. Equilibrium and kinetic models for Pb(II) and Cr(VI) adsorption were studied. Results of the adsorption equilibria were found to fit better to Langmuir isotherm (R2 = 0.972, 0.966) than Freundlich isotherm (R2 = 0.902, 0.687) for Pb(II) and Cr(VI), respectively. The maximum loading capacity of Cr(VI) and Pb(II) were found to be 4.06 and 0.65 mg/g, respectively. On the other hand, kinetics of Pb(II) and Cr(VI) adsorption on the pumice rock were well defined by the pseudo-second order model (R2 = 0.996, 0.998) for Cr(VI) and Pb(II) respectively. The results obtained showed that the use of pumice can be considered as a promising natural, easily accessible and environmentally friendly adsorbent for efficient quantitative removal of Cr(VI) and Pb(II) from contaminated waste water.