Synthesis of cross-linking chitosan-PVA composite hydrogel and adsorption of Cu(II) ions

Abstract

A cross-linked chitosan-PVA spherical hydrogel (CSH) was synthesized and its structure was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The physical and chemical properties of CSH, such as acid resistance and swelling, were determined. Finally, Cu(II) ion removal by the CSH was investigated, and the effects of experimental parameters, including pH, adsorption time, and regeneration performance were examined. Results revealed that CSH has outstanding stability in strong acid solution, thus extending the useful pH range as an adsorbent material. The maximum capacity of CSH for Cu(II) was obtained to be 62.1 mg/g at 25 °C for 24 h. The adsorption process was best described by a pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuir equation better described the adsorption of Cu(II) on CSH. Moreover, the loaded CSH can be easily regenerated by the HCl-washing method and reused repeatedly for Cu(II) adsorption for up to five cycles.