Efficient removal of Cr(VI) by triethylenetetramine modified sodium alginate/carbonized chitosan composite via adsorption and photocatalytic reduction

Conventional photocatalysts for the removal of hexavalent chromium (Cr(VI)) suffers from low metal uptake capacity, expensive cost, and slow desorption of chromium species from photocatalysts’ surface. In this study, a polysaccharide-derived composite was prepared by embedding carbonized chitosan into triethylenetetramine modified sodium alginate (CTS/CS-50). The chemical modification of sodium alginate and the doping of carbonized chitosan significantly enhanced the adsorption and photocatalysis process of Cr(VI) in aqueous solutions. The synthesized composite has exhibited a maximum adsorption capacity of 144.49 mg/g for Cr(VI), while the removal rate for Cr(VI) could reach 98 % within 80 min under UV light irradiation. Moreover, experimental results suggested that the composite material remained effective with the co-existence of conventional interfering ions. Characterization results indicated that N and O functional groups governed the electrostatic interaction with Cr(VI) and the photo-induced electron-hole pairs for the photo-reduction process. Therefore, CTS/CS-50 can be used as an efficient photocatalyst for the treatment of Cr(VI) containing wastewaters, providing a new pathway for the application of polysaccharide-derived photocatalysts.