Removal Behaviour of Rice (Oryza sativa L) Hulls for Submicro Concentrations of Hg2+ and Cr3+ from Aqueous Solutions: A Radiotracer Study

Abstract

The uptake behaviour of rice (Oryza sativa L) hulls for the micro to trace levels of Hg2+ and Cr3+ from aqueous solutions has been carried out in batch equilibrium experiments, employing a 'radiotracer technique'. The parametric study reveals that the increase of adsorptive concentration (10-8 to 10-2 mol dm-3), temperature (293 to 323 K) and pH ca. (3 to 10) enhances the removal of these ions and from thermal and from kinetic data it is inferred that the sorption of these metal ions on rice hulls follows first order rate law, obeys Freundlich isotherm and is endothermic in nature. Desorption experiments allow further conclusion that the process is apparently irreversible as no significant desorption could take place in the bulk concentration of the adsorptives.