Removal of chromium(VI) from contaminated drinking water by ecofriendly adsorbent: equilibrium, isotherm and kinetic study

Hexavalent chromium in drinking water is reported as well known carcinogen. This paper examines an efficient adsorption process of Cr(VI) from drinking water. The ability of developed Eucalyptus (Eucalyptus globulus) bark carbon as an adsorbent for Cr(VI) removal from synthetic sample was studied. The experiments were done in the batch process. Effects of adsorbent quantity, pH, contact time, initial Cr(VI) concentration and agitation rate were investigated on removal of chromium(VI). Approximately 95% of hexavalent chromium (10 mg L⁻¹) was removed at pH 3 within 21 hours at 150 rpm and the concentration reached upto permissible limit recommended by standard agencies. The results indicate that the Langmuir model fits the data better than the Freundlich adsorption isotherm model. The adsorption follows second order kinetics for Cr(VI) removal in this study. The maximum adsorption capacity of 23 mg g⁻¹ was found for the Cr(VI) adsorption. Characterization of the developed adsorbent was performed by SEM and EDX analysis and the results of the characterization supported surface nature and composition of the adsorbent.