Photoreduction of chromium(VI) in microstructured ceramic hollow fibers impregnated with titanium dioxide and coated with green algae Chlorella vulgaris.

Here we propose an innovative photocatalytic hybrid system for the reduction of hexavalent chromium (Cr(VI)) from aqueous solutions. The hybrid system was composed of titanium dioxide (TiO) immobilized in the micro-voids of asymmetric alumina hollow fibers and of the green algae Chlorella vulgaris coated on the outer sponge-like layer of the fiber. The photoreduction of Cr(VI) was systematically studied in different systems: single systems with TiO or algae; the synergistic system of algae combined with TiO; and the proposed hybrid system composed of TiO and algae supported in ceramic hollow fibers. Morphological and energy dispersive spectroscopy analyses showed that TiO and the algae were properly supported in the substrate (alumina hollow fibers). For an initial Cr(VI) concentration of 10 mg L and dosages of 1 g L of TiO and algae, the hybrid system resulted in total Cr(VI) reduction after 16 h of process. Additionally, the efficiency of the hybrid system for Cr(VI) reduction was reduced in only 9% after 5 cycles of reuse and in 42% after 10 cycles of reuse. Thus, micro-structured ceramic hollow fibers impregnated with TiO and decorated with the green algae C. vulgaris was efficient for Cr(VI) reductions.