Photoreduction of Cr(VI) from acidic aqueous solution using TiO2-impregnated glutaraldehyde-crosslinked alginate beads and the effects of Fe(III) ions

To overcome the limitation of powder TiO2, the TiO2-impregnated glutaraldehyde-crosslinked alginate beads (TIGCAB) were prepared. The TIGCAB were characterized by DC, DBM, SEM, BET, XRD, Raman and TG. These synthesized beads were applied to reduce toxic Cr(VI) to Cr(III) in acidic aqueous solution under UV irradiation. In the system without TIGCAB or UV light, no chromium reduction was observed. The reduction rate of Cr(VI) was about 8% when the system was exposed to UV irradiation with blank beads. Photoreduction rate of Cr(VI) decreased with increasing pH. The reduction efficiency of Cr(VI) decreased with the increase of initial Cr(VI) concentration in the range of 5-20 mg L−1. Fe(III) ions improved the photoreduction of Cr(VI) because they can promote the trapping of electrons and holes. Moreover, TIGCAB can maintain full photoreduction activity for at least three cycles. The results show that TIGCAB are promising materials for the photoreduction of Cr(VI) from acidic aqueous solution in environmental pollution cleanup.