Effect of pH, ionic strength and temperature on sorption of Pb(II) on NKF-6 zeolite studied by batch technique

The effect of pH, ionic strength, solid/liquid ratio, contact time and temperature on sorption of Pb(II) to NKF-6 zeolite is investigated using batch technique under ambient conditions. The NKF-6 zeolite is characterized using XRD and FTIR. The sorption results indicate that the sorption of Pb(II) on NKF-6 zeolite is strongly dependent on pH. The sorption of Pb(II) is affected by ionic strength at pH < 6, while it is independent of ionic strength at pH > 6. The sorption of Pb(II) is dominated by ion exchange or outer-sphere surface complexation at low pH values, and by inner-sphere surface complexation at high pH values. The thermodynamic parameters (Delta H(0), Delta S(0) and Delta G(0)) calculated from the temperature dependent sorption isotherms suggest that the sorption of Pb(II) on NKF-6 zeolite is endothermic and spontaneous process. The results are quite important to understand the interaction of Pb(II) with zeolite in aqueous solutions. This investigation shows that the NKF-6 zeolite can be used as a suitable adsorbent for the preconcentration and solidification of Pb(II) from large volumes of aqueous solutions. (C) 2010 Elsevier B.V. All rights reserved.