Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads: Preparation, characterization and application for adsorption of dye from aqueous solution

Abstract

Novel magnetic chitosan/poly(vinyl alcohol) hydrogel beads (m-CS/PVA HBs) were prepared by an instantaneous gelation method and characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). Results of characterization indicated that m-CS/PVA HBs have been prepared successfully without damaging the crystal structure of Fe 3O 4 and their saturation magnetization were about 21.96emug -1. The adsorption capacity of Congo Red on the m-CS/PVA HBs was 470.1mgg -1. The adsorption was well described by pseudo-second-order kinetics and Langmuir equation. Positive value of enthalpy change (ΔH °) (13.32kJmol -1) showed that the adsorption was endothermic and physical in nature. The values of Gibbs free energy change (ΔG °) were found to be -3.321kJmol -1 at 298K for m-CS/PVA HBs, indicating the spontaneity of Congo Red adsorption. Therefore, the m-CS/PVA HBs could be employed as a low-cost alternative to other adsorbents in the removal of dyes from aqueous solution. © 2011 Elsevier Ltd.