Photo-reduction of Cr(VI) in a solution with single or multi-inorganic anions was evaluated. The results show that 38.5 μM Cr(VI) is photo-reduced in the presence of NO3- at pH 1. The photolysis of NO3-, producing NO2- or H2O2, may contribute to Cr(VI) reduction. The addition of 0.001-0.1 M chlorite to NO3- enhanced Cr(VI) photo-reduction when 35.8 μM Fe(III) was present. This enhancement was the combinative result of photolysis of NO3- and Fe-Cl complexes, leading to the formation of NO2- and Fe(II), respectively, for Cr(VI) reduction. On the contrary, a significant decrease in Cr(VI) photo-reduction was observed with the addition of PO43- and SO42-. This decrease was due to their strong competition with Fe(III) from Cl-, resulting in a marked decrease in the concentrations of Fe-Cl complexes. The results suggest that a direct irradiation of acidic wastewaters containing Cl-, NO3-, and Fe(III) is a feasible strategy for eliminating Cr(VI).
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Health, Toxicology and Mutagenesis