期刊
CHEMOSPHERE
卷 84, 期 8, 页码 1095-1101出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2011.04.051
关键词
Goethite; EPR; OH radicals; Singlet oxygen; Hydrogen peroxide
资金
- Ministry of Education, Science, and Technology (MEST) of Republic of Korea [2010-0014829]
- Korea Institute of Construction Technology (KICT) [2011-0060-3-1]
- National Research Foundation of Korea [2010-0014829] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
The generation of reactive species in an aqueous goethite suspension, under room light and aeration conditions, was investigated using the electron paramagnetic resonance (EPR) technique employing spin trap agents. The trap reagents, including 5,5-dimethylpyrroline N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP), were used for the detection of OH radicals (OH(center dot)) and singlet oxygen ((1)O(2)), respectively. On the addition of DMPO to the goethite suspended solution, a DMPO-OH adduct was formed, which was not decreased, even in the presence of the OH(center dot) scavenger, mannitol. This result implied a false positive interpretation from the DMPO-OH EPR signal. In the presence of TEMP reagent, a TEMP-O signal was detected, which was completely inhibited in the presence of the singlet oxygen scavenger, sodium azide. With both DMPO-OH and TEMP-O radicals in the presence and absence of radical scavengers, singlet oxygen was observed to be the key species formed in the room-light sensitized goethite suspension. In the goethite/H(2)O(2) system; however, both OH(center dot) and singlet oxygen were generated, with significant portions of DMPO-OH resulting from both OH(center dot) and singlet oxygen. In fact, the DMPO-OH resulting from OH(center dot) should be carefully calculated by correcting for the amount of DMPO-OH due to singlet oxygen. This study reports, for the first time, that the goethite suspensions may also act as a natural sensitizer, such as fulvic acids, to form singlet oxygen. (C) 2011 Elsevier Ltd. All rights reserved.
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