Optimum Conditions for the Removal of Cr(VI) using Modified Eucalyptus Bark

Abstract

The aims of this study were response surface modeling and optimization of Cr(VI) removal from solution using formaldehyde-modified eucalyptus bark. A high removal rate of Cr(VI) was achieved under the conditions of low adsorbent dosing quantity and high initial concentration of Cr(VI). Analysis of variance showed a high multiple coefficient of determination (R 2 =0.9875), adjusted determination coefficient (R 2 Adj=0.9714), and the good second order regression equation. The initial concentration of Cr(VI) was 40.15 mg/L, adsorbent dosing quantity 3.40 g/L, and initial reaction pH 2.78, and the largest removal rate was 99.998% under the optimum reaction conditions. Langmuir and Freundlich isothermal models described well adsorption of Cr(VI) by the modified stringy bark. Adsorption kinetics studies showed that the adsorption was controlled by multiple factors, dominated by chemical adsorption. The adsorption was found to be spontaneous and endothermic, with △G 0 < 0, △H 0 > 0, and △S 0 > 0. Adsorption of Cr(VI) by formaldehyde-modified stringy bark was partly controlled by REDOX reactions. The adsorbents were characterized by SEM and FTIR.

Application of Raw and Alkaline-modified Coconut Shaft as a Biosorbent for Pb2+ Removal

“…where ' ' and 'n' are the adsorption capacity (mg/g)(1/mg) 1/n and adsorption intensity (dm 3 /g) n (Sengil et al 2009;Niu et al 2014). The greater the value of n, the greater the bonding onto the surface of the biosorbent, wherein n=1 indicates linear adsorption.…”