کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4416169 1307771 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Photosensitized reduction of DDT using visible light: The intermediates and pathways of dechlorination
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم محیط زیست شیمی زیست محیطی
پیش نمایش صفحه اول مقاله
Photosensitized reduction of DDT using visible light: The intermediates and pathways of dechlorination
چکیده انگلیسی

A reaction mixture containing DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), methylene green (as the photosensitizer), and triethylamine (as the electron donor) in acetonitrile:water (1:1) was irradiated by an ordinary 150-W GE-Miser spotlight to facilitate visible-light photosensitized DDT dehalogenation. The intermediates and reaction products were identified by GC/MS (gas chromatography/mass spectrometer) and NMR (nuclear magnetic resonance). The photosensitized dehalogenation method partially degraded DDT via an electron transfer relay mechanism. Results indicate that DDT lost about three chlorines after a total of 19 days of irradiation. Aliphatic chlorines were found to be removed easier than aromatic chlorines. Various types of reductants were compared for electron donation efficiency, and photosensitizer concentration was optimized for our reaction system. In most cases, clean and simple dechlorinated products were observed. The proposed photosensitized reduction was coexisted with a thermal elimination effect for the first chlorine removal of DDT, and the photosensitized electron transfer reduction was shown to be the dominating mechanism responsible for further dechlorination after the initial stage. A sequential dechlorination pathway was proposed, with each successive dehalogenation, the reaction proceeds more slowly. The results have shown the feasibility of utilizing visible light, nontoxic dyes and electron donors to render a toxic compound less toxic and to enhance the natural carbon regeneration rates.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemosphere - Volume 66, Issue 6, January 2007, Pages 1003–1011
نویسندگان
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