Encapsulation of nanoporous MCM-41 in biopolymeric matrix of calcium alginate and its use as effective adsorbent for lead ions: Equilibrium, kinetic and thermodynamic studies

In this study, a new composite adsorbent was synthesized by encapsulation of the nanoporous MCM-41 in the biopolymeric matrix of calcium alginate for developing the chemical and physical properties of MCM-41. The alginate-MCM-41 composite (ALG-MCM-41) was characterized using powder X-ray diffraction and nitrogen adsorption-desorption isotherm data. Adsorption behavior of alginate-MCM-41 composite for lead ions was investigated. The effect of pH, contact time, temperature and initial concentration of lead on lead adsorption were studied by batch method. The kinetics analysis revealed that the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. The thermodynamic studies indicated the endothermic and spontaneous nature of adsorption. Freundlich and Langmuir models were used for mathematics description of the adsorption isotherm. Due to the remarkable adsorption capacity (140.84 mgPb/g), fast kinetics and good mechanical stability, the present composite can be used as a novel adsorbent for an efficient removal of Pb (II) from aqueous solution. (C) 2012 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.