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 N-2 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.