【作者】 程燕；

【导师】 花日茂；

【作者基本信息】 安徽农业大学 ， 农药学， 2004， 硕士

【摘要】 本文主要以高压汞灯、紫外灯、太阳光为光源，研究了酰胺类除草剂丙草胺在水溶液中的光解动态，并在高压汞灯光照下，分别研究了温度、水质、pH缓冲液、表面活性剂、硝酸盐和亚硝酸盐、色素、金属离子以及化肥对丙草胺光解的影响，同时以PNDA为探针，初步研究了双氧水对丙草胺光解影响机理。主要研究结果如下：1.丙草胺水溶液在太阳光下不易发生直接光解，光解半衰期为87h，在高压汞灯和紫外光下光照下光解迅速，且光解动态符合一级动力学，光解半衰期分别为5.12min、39.8min。2.在一定温度范围内，温度能较大地影响丙草胺的光解动态。在10℃、25℃、40℃时丙草胺的光解半衰期分别为26.65min、23.1min、21.3min，随着温度的升高，光解速率增大，但同时增大的幅度逐渐减少。3.不同的pH值同样影响丙草胺的光解速率，光解速率为pH9>pH7>pH4，光解半衰期分别为24.96min 、30.66min、 37.67min，光解速度随着pH值增加而增加，即在同等光源下，碱性条件有利于丙草胺的光解。4.丙草胺在5种不同水质中的光解速率有明显差异，在高压汞灯光照下光解速率为重蒸水>董铺水库水>巢湖水>琥珀潭水>稻田水，其中重蒸水中的光解半衰期为22.65min，稻田水中为38.5min。影响机理和不同水质的理化性质相关。5.阴离子表面活性剂SDBS、阳离子表面活性剂CTAB、混合型表面活性剂0206B对丙草胺均表现出不同程度的整体光猝灭效应，但作用机理却不相同。而非离子型表面活性剂Tween-60对丙草胺表现较明显的光敏化作用。表面活性剂对丙草胺的光敏或猝灭强度受表面活性剂性质、吸收光谱、添加剂量等诸多因素影响。混合型表面活性剂0206B的主要成分配比中农乳500和浓乳603分别以1∶0， 0∶1，1∶1，1∶2，2∶1浓度比混合时，均明显地延缓了丙草胺的光解，并且在1：1条件下，这两种成分对丙草胺表现的猝灭作用最强，为协同作用效应。6.硝酸盐、亚硝酸盐在实验添加浓度范围内，对丙草胺光解均表现出猝灭效应,效应强度随硝酸盐和亚硝酸盐浓度增加而增强。 7.Fe3+离子促进了丙草胺的光解，而Cu2+、Pb2+对丙草胺的光解表现出微弱的猝灭作用，这主要与金属离子本身的氧化还原性质相关。 8.甲基紫的加入对丙草胺的光解表现出猝灭效应，半衰期分别由单独光解的24.31min延长至26.35min、27.18min、32.53min，甲基紫的存在可能参与了丙草胺竞争羟基反应。不同浓度的核黄素均对丙草胺的光解有敏化作用，半衰期分别由5.57min<WP=7>缩短到5.05min、4.78min、4.19min，光解速率随核黄素添加浓度增大而增大。甲基绿等4种色素的加入对丙草胺光解影响不明显。 9.磷酸二氢钾和氯化钾不同浓度的添加对丙草胺光解均表现出光猝灭作用，猝灭率效率分别和化肥物质添加浓度呈正相关，磷酸二氢钾主要改变了水溶液的pH，而氯化钾主要是由于Cl-的作用。尿素和碳酸氢铵也由于pH对丙草胺光解具有微弱的敏化作用，对丙草胺的光敏率与添加浓度显示出正相关性。10. H2O2由于能通过光解产生羟基自由基，从而对丙草胺表现显著的光敏化降解作用。高压汞灯下H2O2使丙草胺的光解速率提高了4.55～1.74倍，但光敏率随H2O2浓度添加至一定量后而减弱。在太阳光下，H2O2使丙草胺的降解速率提高了33.6～81.58倍，敏化作用却随添加浓度而增强，可能两种光源辐射波长的不同，丙草胺的降解方式也有差异。更多还原

【Abstract】 The photolytic kinetics of Anilide herbicides pretilachlor in aqueous solution irradiated by HPML, UV and sunlight was investigated. The following effects on photolysis of pretilachlor under HPML were also studied: temperature, water types, pH buffers, surfactants, nitrate and nitrite, dyes, metallic ions and fertilizers. At the same time, the effect mechanism of H2O2 on pretilachlor was roughly expounded with PNDA as a·OH probe. The main results were summarized as follows:1. The direct photodegradation rate of pretilachlor in aqueous solution by sunlight was slow, the half-life was 87h. however it quickly under HPML and UV irradiation, the half-life was 5.12 and 39.8miniutes.the photolysis follow the first order kinetics.2. The photolysis of pretilachlor was greatly affect under different temperature. When the temperature was 10℃,25℃,40℃,the half life of pretilachlor was 26.65min,23.1min,21.3min. 3.The pH value has significant effect on pretilachlor photolysis, the photolysis rate constant pH9>pH7>pH4, the half-lift was 24.96min 、30.66min、 37.67min.At the same condition, pretilachlor could be easily photodegradated in alkaline solution.4.The photolytic rates of pretilachlor in five types of water ranged as: distilled water>reservoir water (DongPu)>lake water(ChaoHu)> pond water (HuPo)> paddy water. The half-life of pretilachlor was 22.65min with distilled water while 38.5min with paddy water. The effect mechanism was related to the physical and chemical properties of the water samples. 5.Under HPML, surfactant SDBS, CTAB, 0206B both showed photo-quenching effects to pretilachlor. But there mechanisms were different. Nonionic surfactant Tween-60 enhanced the photodegradation rate of pretilachlor. The result showed that the degree of photosensitive or photo-quenching effects of surfactants on the photolysis of pretilachlor was affected by properties of surfactants, UV spectra, the additive dosage and so on. The composition of the mixture surfactant 0206B: Nongru 500and Nongru 603 was mixtured by 1∶0，0∶1，1∶1，1∶2，2∶1, they both slow down the photolytic rate of pretilachlor. When 1:1, the photo-quenching rate was the biggest in their added dosage range, and they worked in coordination.6. Both nitrate and nitrite showed photoquenching effects on pretilachlor in their added <WP=9>dosage range. The photoquenching rate was improved with the increases of nitrate and nitrite concentration.7. Fe3+ enhanced the photodegradation rate of pretilachlor while Cu2+, Pb2+ exhibited photoquenching effects on pretilachlor. The mechanism has relation to the oxidative and reductive properties of metallic ions.8.Crystal Violet showed photo-quenching effect on pretilachlor. Different dosages crystal Violet made half-life of pretilachlor prolong from 24.31min to 26.35min, 27.18min, 32.53min. At the same time, crystal viboflavin sensitized the pretilachlor photolysis, and the photolytic rate was improved with the increases of crystal viboflavin concentration. Methyl green, methyl red, methyl blue and methyl orange had little effect on photolysis of pretilachlor. 9.Different dosages of KH2PO4 and KCl both showed photo-quenching effects on pretilachlor, and photo quenching rate improved with the increases of fertilizer concentration. NH4HCO3 and urea sensitized the pretilachlor photolysis. But their mechanisms were different. KH2PO4, NH4HCO3 and urea change the pH value of solution because of their properties. The Cl- of KCl could absorb·OH competing with pretilachlor. 10. H2O2 produced hydroxyl radical (·OH) upon UV irradiation, so the photodegradation of pretilachlor was greatly promoted. Under HPML irradiation, the photolysis rates of pretilachlor were improved about 4.55～1.74 times. But with the increasing of H2O2 dosage, the photosensitive rate was decreased. Under sunlight, the photolysis rates of pretilachlor were improved about 33.6～81.58 times with H2O2. and the photosensitive rate was improved with increasing dosage of H2O2. The photodegradation path of pretilachlor may be different und更多还原