Comparative study on adsorption and desorption of Cu(II) ions by three types of chitosan–zeolite composites

Abstract

Three different chitosan–zeolite composites (CZ-0, CZ-1 and CZ-2) were prepared and used to remove Cu(II) ions from aqueous solutions. The composites were characterized using infrared spectroscopy, surface area and pore size analysis, CHN analysis, scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX) analysis, thermogravimetric analysis, and X-ray diffraction (XRD) analysis. The pH point of zero charge (pHPZC) was 7.76, 8.30 and 5.53 for CZ-0, CZ-1 and CZ-2 respectively. The adsorption of Cu(II) by using chitosan–zeolite composites were best described by pseudo-second order kinetic model for CZ-0, CZ-1 and CZ-2. Based on Langmuir isotherm model, the maximum adsorption capacity were 25.61, 51.32 and 14.75mg/g for CZ-0, CZ-1 and CZ-2 respectively. A kinetic model consisting of second-order adsorption and first-order desorption were used to describe the binding behavior of adsorption–desorption process in Cu(II) loaded chitosan–zeolite composites. All the composites were loaded with Cu(II) ions up to maximum adsorption capacity based on the maximum adsorption capacity obtained from the Langmuir isotherm model. The results showed that the kinetic model was fitted well to the experimental data showing that –CH2OH of chitosan act as major binding site for Cu(II) ion.