Removal of Zn (II) from aqueous solution by using hybrid precursor of silicon and carbon

Hybrid precursor (HP) of silicon and carbon was synthesized from rice hulls by a novel low temperature method, using sol-gel route. The potential of hybrid precursor to remove Zn (II) ions from aqueous solutions was investigated under different experimental conditions. Hybrid precursor removes Zn (II) ions with efficiency higher than 95% at low concentration. The data revealed that initial uptake was rapid and equilibrium was established in 30 min. Pseudo first order, Pseudo second order and Intraparticle diffusion kinetic models were applied to the kinetic data and it was found that adsorption process followed pseudo second order with activation energy of 1.093 kJ mol(-1). Zn (II) removal was quantitatively evaluated using Langmuir and Freundlich isotherm model and monolayer sorption capacity show the value 28.76 mg/g indicating the affinity of HP for Zn (II) ions. The negative value of Gibbs free energy obtained in this study with hybrid precursor confirms the feasibility and spontaneous nature of adsorption process. (C) 2009 Elsevier Ltd. All rights reserved.