A comparative study of magnetic chitosan (Chi@Fe3O4) and graphene oxide modified magnetic chitosan (Chi@Fe3O4GO) nanocomposites for efficient removal of Cr(VI) from water.

Magnetic chitosan (Chi@Fe3O4) nanocomposite was synthesized and modified with graphene oxide (Chi@Fe3O4GO) and the potential of both materials as adsorbents was assessed for the removal of chromium (Cr(VI)) from water. The physico-chemical characteristics of magnetic nanocomposites were studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy and Brunauer-Emmett-Teller (BET). The synthesized adsorbents exhibited varied Cr(VI) removal efficiency at solution pH 2. The reaction kinetics correlated well with the pseudo-second-order model. The maximum adsorption capacity was found to be 142.32 and 100.51 mg g-1 for Chi@Fe3O4 and Chi@Fe3O4GO, respectively. Analysis of thermodynamic parameters suggested that the reaction occurred spontaneously and was endothermic in nature. Reusability studies showed that the adsorbents can be reused for up to four cycles of regeneration. Fixed bed column experiments revealed that the adsorption performance of Chi@Fe3O4 was affected by the flow rate, adsorbent loading and influent metal ion concentration. The results suggest that the prepared adsorbents have the potential to be used in removing Cr(VI) ions from contaminated water.