Biosorption of Cu(II) from aqueous solution by grape waste: Equilibrium, Kinetics and Thermodynamics

Abstract

In present study, an industrialwaste of wine factory, grape waste, was used as a biosorbent precursor for the removal of Cu(II) from aqueous solutions. Optimum biosorption conditions were determined as a function of pH, biosorbent dosage, initial metal ion concentration, contact time and temperature of solution. Equilibrium data were analyzed using Langmuir, Freundlich and Temkin isotherm models. Cu(II) biosorption on grape waste was well described by Freundlich model. In addition, the modeling of biosorption isotherms were investigated using non-linear regression and it was found that the experimental data were fitted to the Freundlich isotherm model. The pseudo-first order and pseudo-second order kinetic models were applied using linear and non-linear regressions to test the kinetic data and it was observed that biosorption of Cu(II) followed pseudo-second order model for both regressions. The thermodynamic parameters, namely DG°, DH°, DS° were calculated to predict the nature of biosorption and these results indicated that the biosorption process occured spontaneously. According to the experimental results, grape waste seems to be an effective and alternative biosorbent precursor for the removal of heavy metal ions from aqueous solutions in terms of natural and abundant availability, its high biosorption capacity and low cost.