Preparation and characterization of iron(III) complex of an amino-functionalized polyacrylamide-grafted lignocellulosics and its application as adsorbent for chromium(VI) removal from aqueous media

Abstract

This study concerns with the development of a new adsorbent, iron(III) complex of an amino-func- tionalized polyacrylamide-grafted coconut coir pith (CP), a lignocellulosic residue, for Cr(VI) in water and industry effluents. The adsorbent (AM-Fe-PGCP) was characterized by FTIR, EDS, Mössbauer, surface area analyzer, TG/DTG, and potentiometric titration. The effects of contact time, initial sorbate concentration, pH, dose of adsorbent, and temperature on Cr(VI) adsorption were studied to optimize the conditions for maximum adsorption. The kinetics of sorption was investigated using pseudo-first-order and pseudo-second-order rate equations with the later giving a better fit to the experimental data. The mechanism of sorp- tion was found to be film diffusion controlled. The Langmuir isotherm model yields a much better fit than the Freundlich and Dubinin-Radushkevich models with maximum adsorption capacity of 142.76 mg/g at 30°C. Simulated industry wastewater sample was treated with AM-Fe-PGCP to demonstrate its efficiency in removing Cr(VI) from wastewater. The alkali treatment (0.1M NaOH) and re-introduction of Fe3+ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity. © 2009 Wiley Periodicals, Inc.