Functionalized chitosan nanocomposites for removal of toxic Cr (VI) from aqueous solution

Starting from the biopolymer chitosan, two new functionalized chitosan nanocomposities, (CTS-Cin) and (Fe3O4@CTS-Cin) were synthesised and explored for the removal of toxic chromium from aqueous solution. The two chitosan based adsorbents were prepared by co-precipitation method under N2 conditions and fully characterized by means of different analytical techniques, FT-IR, EDS, XRD, SEM, HR-TEM and VSM. Adsorption mechanism of toxic Cr (VI) was performed by batch experiments as a function of pH, adsorbent dosage, contact time and initial hexavalent chromium concentration. The adsorption isotherm and kinetics were fitted well by Langmuir and pseudo-second–order model indicating that the adsorption process is monolayer adsorption. The maximum adsorption capacity for CTS-Cin adsorbent at 298 K is 61.35 mg/g at pH = 2 and it achieved adsorption equilibrium within 35 min. However, Fe3O4@CTS-Cin adsorbent achieved adsorption equilibrium within 80 min and its maximum adsorption capacity is 58.14 mg/g at pH = 3. These results indicate that the two modified adsorbents represent promising adsorbents that would have a practical impact on wastewater treatment applications. •Two new modified chitosan adsorbents, CTS-Cin and Fe3O4@CTS-Cin has been prepared and fully characterized.•The prepared adsorbents were used to investigate the adsorption properties of Cr(VI) metal ion in an aqueous solution.•The sorption of Cr(VI) ion fit well the second order reaction and Langmuir isotherm model.•The maximum adsorption capacity of Cr(VI) onto the CTS-Cin and Fe3O4@CTS-Cin was 61.35 mg/g and 58.14 mg/g, respectively.•The two adsorbents represent promising adsorbents that would have a practical impact on water treatment applications.