Biosorption of Cu(II) ions as a method for the effective use of activated carbon from grape stalk waste: RMS optimization and kinetic studies

Abstract

ABSTRACT This study was undertaken to examine the effect of such biosorption factors as initial Cu(II) concentration, biosorbent dosage, reaction temperature, contact time and mixing speed on the efficiency of removal Cu(II) ions from wastewater using activated carbon from grape stalk waste. In this case, Response Surface Methodology (RSM) was used in conjunction with a Box–Behnken design of experiments to predict the final Cu(II) concentration (CFin ), while considering the previously mentioned biosorption factors. In an attempt to obtain the maximum removal of final Cu(II) concentration, while minimizing energy consumption, the Multi-Response Surface Methodology (MRS) was used. Three possible optimizations were proposed for the maximum elimination of final Cu(II) in this case. The maximum (100 mg/L), minimum (2 mg/L) and intermediate (51 mg/L) values of the study were used for the initial Cu(II) concentration. The optimal values that were reached were 92.21% when the initial copper concentration was 51 mg/L and the activated carbon dose, temperature, mixing speed and reaction time, were, respectively, 0.895 g/L, 20.036°C, 105.313 rpm and 30.181 s. Also, in regard to thermodynamic studies, the experimental equilibrium data provided a good fit using the Freundlich model, whereas the kinetic data were efficiently by the pseudo-second order. These results support the use of grape stalk waste in the production of activated carbon for the removal of Cu(II) ions from water. This could help to improve the economics of treating wastewater.