Abstract

In this paper, the adsorption of Cr(VI) by a natural polysaccharide, psyllium mucilage has been reported by conducting batch-type experiments at 37°C. Psyllium mucilage beads (PPB) were cross-linked with glutaraldehyde (GLA) to improve the chemical resistance and mechanical properties of beads. PPB and crosslinked (PPB-GLA) were characterized by FTIR (Fourier-Transform Infrared Spectroscopy) and SEM (Scanning Electron Microscopy). The adsorption rate and capacity of both adsorbents, PPB and PPB-GLA were measured. Adsorption experiments using AAS (Atomic Absorption Spectroscopy) were done at varying concentrations of hexavalent chromium (Cr(VI)), amount of PPB and PPB-GLA, time and pH. Adsorption of Cr(VI) was highly dependent on pH of the medium. One gram of PPB-GLA adsorbed 456 mg of chromium at pH 3. Cr(VI) adsorption has also been confirmed by EDAX (Energy Dispersion Analysis by X-ray) and DRUV (Diffuse reflectance UV-VIS) analysis. Equilibrium data correlated with the Langmuir model and kinetic experimental data fitted with the second-order kinetics.

Keywords: Adsorption isotherms, adsorption kinetics, chromium removal, green materials beads, psyllium.