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International Journal of Photoenergy
Volume 2012, Article ID 381971, 7 pages
Research Article

Photoreduction of Cr(VI) Ions in Aqueous Solutions by UV/ T i O 2 Photocatalytic Processes

1Department of Cosmetic Application and Management, St. Mary’s Medicine Nursing and Management College, Yi-Lan 266, Taiwan
2Holistic Education Center, Mackay Medical College, Taipei 252, Taiwan
3Department of Environmental Engineering, Da-Yeh University, Changhwa 512, Taiwan

Received 1 June 2012; Revised 19 July 2012; Accepted 31 July 2012

Academic Editor: Meenakshisundaram Swaminathan

Copyright © 2012 Chih Ming Ma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study discussed the photoreduction of Cr(VI) ions in aqueous solutions by UV/TiO2 photocatalytic processes under various operational factors. Experimental results showed that the removal rate of Cr(VI) increased with decreasing solution pH values and with increasing dosages of organic compounds, indicating that the recombination rate of electrons and h+ can be retarded in the reaction systems by the addition of the scavenger, thus raising the reaction rate of Cr(VI). The relationship of the chemical reaction rate of Cr(VI), TiO2 dosage, and changes of Cr(VI) concentration was expressed by the pseudo-first-order kinetic equation. Comparing the experimental results of two different doping metals in modified TiO2 photoreduction systems, the removal rate of Cr(VI) by the Ag/TiO2 process is larger, possibly because the electron transferring ability of Ag is superior to that of Cu. However, the photoreduction rates of Cr(VI) by modified UV/TiO2 processes are worse than those by a nonmodified commercial UV/TiO2 process.