Fabrication of chitosan/magnetite-graphene oxide composites as a novel bioadsorbent for adsorption and detoxification of Cr(VI) from aqueous solution.

By utilizing the synergistic effect of chitosan (CS), magnetite (FeO) particles, and graphene oxide (GO), a series of efficient and eco-friendly chitosan/magnetite-graphene oxide (CS/MGO) composites were fabricated through a facile chemical route. First, FeO particles were chemically deposited on the surface of GO to fabricate MGO hybrid. Then, chitosan was attached on MGO sheets, assembling to CS/MGO composites. According to the results of characterization, the covalent Fe-O-C bonds, electrostatic attraction, and hydrogen bonding between GO, FeO, and chitosan ensure excellent structural stability and physico-chemical properties. The adsorption of Cr(VI) onto CS/MGO composites was also carried out under various conditions (content of CS, pH, initial concentration, contact time, and temperature). The CS/MGO composites possess high removal capacity for Cr(VI) from aqueous solution. Moreover, results also suggested that the CS/MGO composites had a strong reducing action for Cr(VI). When adsorption occurred, Cr(VI) and Cr(III) were simultaneously removed by CS/MGO composites. In addition, CS/MGO composites could retain good Cr(VI) removal efficiency after reuse over five cycles. CS/MGO composites are expected to have potential applications as easily regenerative bioadsorbents for Cr(VI) polluted water cleanup.