Adsorption of Cr (III) from aqueous solution by groundnut shell

Adsorption and de-sorption of chromium (III) ions on groundnut shell from aqueous solutions have been studied using batch adsorption techniques with respect to the influence of contact time, pH, adsorbent dose, initial chromium concentration and particle size. Appropriate adsorption isotherm and kinetic parameters of chromium (III) adsorption on groundnut shell have also been determined. The results of this study showed that adsorption of chromium (III) by groundnut shell reached to equilibrium after 360 minutes of the experiment and after that a little change of chromium removal efficiency was observed. Maximum chromium removal (87.5 %) was obtained at pH 7.0. The adsorption of chromium by groundnut shell was found to decrease with the higher chromium concentrations in aqueous solutions, lower adsorbent doses and higher particle sizes. The desorption efficiencies with 0.5M KOH was observed 78%. It is observed that the adsorption of chromium (III) by groundnut shell follows Langmuir and Freundlich isotherm equation. The kinetic of the adsorption process follows the first order kinetics with a rate constant of 0.01min-1. The results indicate that groundnut shell can be employed as a low cost alternative to commercial adsorbents in the removal of chromium (III) from water and wastewater.