Canadian Journal of Chemical Engineering, Vol.91, No.5, 814-821, 2013
Application of Chattim tree (devil tree, Alstonia scholaris) saw dust as a biosorbent for removal of hexavalent chromium from contaminated water
Devil tree saw dust; a novel biosorbent has been utilised successfully for the removal of hexavalent chromium from contaminated water. Batch adsorption procedure is utilised to test the ability of saw dust as an adsorbent for hexavalent chromium (reduction coupled adsorption). The contribution of various parameters on sorption, such as contact time, sorbate concentration, pH of the medium and temperature were estimated and maximum uptake of hexavalent chromium from contaminated water was 333.33mgg1 at pH 2.0 and temperature of 35 degrees C. Hexavalent chromium uptake from contaminated water followed the pseudo-first-order rate expression. The standard free energy change (G0), standard enthalpy change (H0) and standard entropy change (S0) have also been evaluated and it has been concluded that the sorption was feasible, spontaneous and endothermic in nature. The process follows well Langmuir isotherm. Fourier Transform Infra-Red (FTIR) spectroscopy and scanning electron microscopy (SEM) of hexavalent chromium loaded and unloaded saw dust were performed, SEM clearly indicates chromium adsorption. FTIR spectroscopy revealed the involvement of carbonyl, hydroxyl and amide groups on the cell surfaces in chromium binding. Very good adsorption capacity and low cost or cost free of devil tree saw dust makes this biosorbent as one of the best adsorbents for removal of hexavalent chromium from contaminated water. (c) 2012 Canadian Society for Chemical Engineering
Keywords:hexavalent chromium;devil tree saw dust;biosorption;sorption isotherm;sorption kinetics;thermodynamic parameters