Synthesis and adsorption properties of chitosan-CDTA-GO nanocomposite for removal of hexavalent chromium from aqueous solutions

Abstract

A novel adsorbent of chitosan-1,2-Cyclohexylenedinitrilotetraacetic acid – graphene oxide (Cs/CDTA/GO) nanocomposite was successfully prepared in the presence of glutaraldehyde as cross linker. The adsorption and removal efficiency of hexavalent chromium (Cr6+) using Cs/CDTA/GO adsorbent were investigated at different adsorption conditions. The prepared adsorbent was characterized by FTIR and SEM. The effects of adsorbent chemical composition, CDTA/GO concentration, adsorbent dose, pH, temperature, contact time and initial metal ion concentration on Cr6+ sorption were investigated. The results showed that the optimum adsorbent dose was 2 g/l at pH of 3.5 and equilibrium time of 60 min. In addition, the temperature and pH were shown with great influence of the adsorption process. The adsorption kinetics of Cr6+ onto Cs/CDTA/GO followed the pseudo-second order model and the adsorption isotherm was well fitted by the Langmuir model. The maximum adsorption capacity of the adsorbent was 166.98 mg/g, and the equilibrium parameter (RL) at different concentrations was less than unity indicating the adsorption of Cr6+ ions onto Cs/CDTA/GO is favorable. Cs/CDTA/GO adsorbent could be regenerated more than three times based on its adsorption/desorption cycles.