Hexavalent chromium removal from aqueous solutions by use of extruded activated carbon. Sorption thermodynamic studies

摘要

This study deals with the adsorption of toxic hexavalent chromium from synthetic wastewater on commercial extruded activated carbon (EAC) Norit Row 0.8 Supra. Batch equilibrium experiments were conducted to evaluate the adsorption performance over the pH range 1.0 - 6.2. The sorption is strongly dependent on the pH of the solution, with Cr(VI) uptake increasing with decreasing pH. The results indicate that Langmuir model provides the best correlation of the experimental data. The standard Gibbs energy change was calculated to evaluate the thermodynamic feasibility of the process, and the negative values found indicate a spontaneous adsorption process. Furthetmore, the separation factor RL and the Freundlich 1/n constant also suggest that adsorption was favorable over the entire studied pH range. On the basis of present study, it can be concluded that the studied sorbent has a high Cr(VI) adsorption capacity and it is feasible to be used in treatment processes destined to remove hexavalent chromium from contaminated waters.