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A mechanism study of light-induced Cr(VI) reduction in an acidic solution.
J Hazard Mater. 2009 May 15; 164(1):223-8.JH

Abstract

The mechanisms of photo-catalytic reduction of Cr(VI) were investigated in acidic solutions with and without Fe(III). In a system without Fe(III), no Cr(VI) reduction was observed in dark conditions; conversely, under light conditions, the reduction reaction rate increased to 0.011 and 0.020microM min(-1) at pH 2 and pH 1, respectively, indicating the occurrence of Cr(VI) photo-reduction. The Cr(VI) photo-reduction reaction was induced by the photolysis of water molecules, leading to O(2) production. Upon the addition of Fe(III), the photo-reduction rate of Cr(VI) was significantly enhanced due to the formation of Fe(II), which is the photolytic product of FeCl(2)(+) and the electron donor for Cr(VI) reduction. However, with the same concentration of FeCl complexes, a strong inhibition of Cr(VI) reduction at pH 2 was observed, compared with pH 1. A possible explanation is that FeOH(2+) becomes predominant with increasing pH and that its photolytic product, the OH free radical, is an oxidant for Fe(II) and Cr(III) and can compromise Cr(VI) reduction. The kinetic result of each photo-reduction reaction pathway shows zero-order kinetics, suggesting that the photolysis reaction of H(2)O or FeCl(2+) is the rate-determining step in each pathway. The results also show the potential of developing a homogeneous photo-catalytic method to treat Cr(VI)-containing water.

Authors+Show Affiliations

Department of Soil & Environmental Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan, ROC.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18789578

Citation

Wang, Shan-Li, et al. "A Mechanism Study of Light-induced Cr(VI) Reduction in an Acidic Solution." Journal of Hazardous Materials, vol. 164, no. 1, 2009, pp. 223-8.
Wang SL, Chen CC, Tzou YM, et al. A mechanism study of light-induced Cr(VI) reduction in an acidic solution. J Hazard Mater. 2009;164(1):223-8.
Wang, S. L., Chen, C. C., Tzou, Y. M., Hsu, C. L., Chen, J. H., & Lin, C. F. (2009). A mechanism study of light-induced Cr(VI) reduction in an acidic solution. Journal of Hazardous Materials, 164(1), 223-8. https://doi.org/10.1016/j.jhazmat.2008.07.145
Wang SL, et al. A Mechanism Study of Light-induced Cr(VI) Reduction in an Acidic Solution. J Hazard Mater. 2009 May 15;164(1):223-8. PubMed PMID: 18789578.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A mechanism study of light-induced Cr(VI) reduction in an acidic solution. AU - Wang,Shan-Li, AU - Chen,Chung-Chi, AU - Tzou,Yu-Min, AU - Hsu,Chia-Lian, AU - Chen,Jen-Hshuan, AU - Lin,Chen-Fang, Y1 - 2008/08/09/ PY - 2008/03/17/received PY - 2008/05/31/revised PY - 2008/07/31/accepted PY - 2008/9/16/pubmed PY - 2009/7/25/medline PY - 2008/9/16/entrez SP - 223 EP - 8 JF - Journal of hazardous materials JO - J Hazard Mater VL - 164 IS - 1 N2 - The mechanisms of photo-catalytic reduction of Cr(VI) were investigated in acidic solutions with and without Fe(III). In a system without Fe(III), no Cr(VI) reduction was observed in dark conditions; conversely, under light conditions, the reduction reaction rate increased to 0.011 and 0.020microM min(-1) at pH 2 and pH 1, respectively, indicating the occurrence of Cr(VI) photo-reduction. The Cr(VI) photo-reduction reaction was induced by the photolysis of water molecules, leading to O(2) production. Upon the addition of Fe(III), the photo-reduction rate of Cr(VI) was significantly enhanced due to the formation of Fe(II), which is the photolytic product of FeCl(2)(+) and the electron donor for Cr(VI) reduction. However, with the same concentration of FeCl complexes, a strong inhibition of Cr(VI) reduction at pH 2 was observed, compared with pH 1. A possible explanation is that FeOH(2+) becomes predominant with increasing pH and that its photolytic product, the OH free radical, is an oxidant for Fe(II) and Cr(III) and can compromise Cr(VI) reduction. The kinetic result of each photo-reduction reaction pathway shows zero-order kinetics, suggesting that the photolysis reaction of H(2)O or FeCl(2+) is the rate-determining step in each pathway. The results also show the potential of developing a homogeneous photo-catalytic method to treat Cr(VI)-containing water. SN - 1873-3336 UR - https://www.unboundmedicine.com/medline/citation/18789578/A_mechanism_study_of_light_induced_Cr_VI__reduction_in_an_acidic_solution_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0304-3894(08)01192-8 DB - PRIME DP - Unbound Medicine ER -