Adsorption of chromate and cupric ions onto chitosan-coated cotton gauze

A chitosan-coated cotton gauze was prepared by UV-curing and tested as adsorbent to remove copper (II) and chromium (VI) ions from water solutions. The adsorbent characterization was carried out by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection (FTIR-ATR). Adsorption of copper and chromium ions onto the gauze was tested in batch process at different experimental conditions. The effects of pH, temperature, contact time and metal ion concentration were investigated. The optimum adsorption took place at pH 3 for Cr(VI) and pH 5 for Cu(II) ions respectively, while the temperature did not affect the adsorption process. Pseudo-first and pseudo-second order models were used to investigate the adsorption kinetics which was found very fast and better described by the pseudo-second order model for both metal ions. The adsorption of Cr(VI) ions was satisfactory described by the Langmuir isotherm, while that of Cu(II) ions showed a better agreement with the Freundlich model.