| The photodegradation of fungicide Fenarimol (FEN) by solar radiation, high pressure mercury lamp (HPML) and ultraviolet radiation (UV) has been studied on glass surface, in water or in organic solution, the effects of four kinds of surfactants and several kinds of pesticides has also been investigated. Some other factors, such as temperature,the water types, pH buffer solution, coloring matter, halogen ions, nitrate/nitrite, metallic ions, hydrogen peroxide and surfactants, their effects on photodegradation of FEN were also observed. The main results were summarized as following:1. The photolytic rate of FEN by three light sources followed the below order: HPML＞UV＞SL. Under sunlight, the photolysis half-life of FEN was 3.3h in acetonitrile, 4.88h in hexane, 20.62h in acetone, and 14.29h in methanol, the half-life under HPML was less than half an hour, but acetone quenched its decomposition and prolonged its half-life up to 288.81min. While the photolytic half-life by UV was delayed to 2-3h, the half-life was10.65h in acetone. It showed the same order of the photolytic rate: acetonitrile＞hexane＞methanol＞acetone. 2.FEN photodegradated very quickly on glass surface. Its photolysis followed the first kinetics equation and the photolytic rate was 84.6% when illuminated 30min by HPML, the photolytic constant and half-life was 0.0659 min-1 and 10.52min respectively. As the same condition the photolytic constant and half-life under sunlight radiation was 0.0492h-1and 13.40h, respectively, the decomposition rate reached 73%. FEN was strongly sensitized by T-60 and SDBS, but SDS quenched its photodegradation and the effect showed the direct proportion with the dosage ratio. The effect of S-20 was complicated,it sensitized the photolysis of FEN slightly when the dosage was 1:1,but quenched the photolysis of FEN. Three pesticides Chlorothalonil, fenpropathrin, fenvalerate effected the photodegradation of FEN, the quenching rate was 22.58%, 39.53% and 26.54%, respectively. The pesticide Phoxim showed strongly effect on the photodecomposition of FEN, and the quenching rate reached 183.2%, prolonged its half-life up to 35.9min. Vinclozolin sensitized the photolysis of FEN, the sensitizing rate reached 38.72%. Other kind of pesticide Cyhalothrin and showed slightly effect.3. The photolytic speed in four different types water ranged as: distilled water ＞ river water(Dongpushuiku)＞pond Water(Heichiba)＞lake water(ChaoHu). The photolysis of FEN in water under sunlight(SL) was very quickly. The effect of temperature was slightly, but increased its photodegradation speed. The half-life of FEN was 6.7min,5.4min and 5.3min when the temperature was 15℃ ,30℃ and 40℃ respectively. Photolysis experiment of FEN in different buffer solution indicted that the instability in acidic solution. The photolysis half-life of FEN was 4.997h in pH 5 buffer solution. But it can be stability in alkaline solution. The photolysis half-life of FEN was 6.863h, 7.434h and 7.543h in pH7, pH9 and pH11 buffer solution respectively. 4.Photosensitizers such as riboflavin, methylene Blue can accelerate the photodecomposition of FEN in low dosage ratio and quench its photodecomposition in large dosage ratio, but crystal violet quenched its photolysis in all the dosage ratio and the quenching effect showed the direct proportion with the dosage ratio.5.Several kind of salt was selected to investigate its effect on photodecomposition of FEN under sunlight radiation. Three kind of halogen ions such as , I- , Br- and Cl- showed great quenching effect, the effect ranged as: I-＞Br-＞Cl-. The nitrate ion and nitrite ion also showed great quenching effect on its photolysis and the effect become stronger with the dosage increased. The results indicated that the effects of salt on the photolysis of FEN was very complicated, the absorb spectrum and spike concentration may be the crucial factor.6.The effect of three kinds of surfactants was also studied, CTAB can photosensitize the photodecomposition of FEN at all the additive dosage ratio. S-...
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