三十烷醇在水体中的光解与水解特性

按化学农药环境安全评价试验准则的要求进行了三十烷醇在水体中光解与水解的试验研究。结果表明，三十烷醇在该试验条件下光降解缓慢，半衰期为５６４ｄ；在５０ｄ的试验期内，三十烷醇在不同酸度的水体中几乎不发生水解。     

二甲基硫醚光解及二甲基二硫醚生成速率研究

用低压汞灯照射二甲基硫醚（ＤＭＳ）,在２０ｍ的长光池中用富里叶红外光谱仪测量其光解产物,结果表明二甲基硫醚光解生成二甲基二硫醚（ＤＭＤＳ）和乙烷。测量其不同光照时间的光解产物,结果表明Ｉｎ＾ｃ０／ｃｔ在直解坐标上是一条直线,说明了二甲基二硫醚生成按生一极反应进行,其生成的速率常数为８．７０×１０＾－５ｓ＾－１用低压汞灯照射ＤＭＳ＋Ｈ２Ｏ２体系,富里叶红外光谱检测其产物,在有足够的Ｈ２Ｏ２情况下,生     

不同量子化学算法在多环芳烃光解行为定量结构-性质关系(QSPR)中的应用

以采用MINDO/3、MNDO和AMI算法计算的17种多环芳烃（PAHs）的前线分子轨道能为分子结构参数,进行了这些PAHs光解速率常数的定量结构－性质相关（QSPR）的研究,并与基于PM3算法得到的QSPR模型进行了比较,研究结果表明,应用PM3算法得到的前线分子轨道能进行这些PAHs光解速率常数QSPR拟合的结果最好,其次是AMI算法,而MINDO/3和MNDO算法得到的结果较差。     

乙烯菌核利在水溶液中的光解动力学

以高压汞灯和太阳光为光源,研究乙烯菌核利在重蒸水、自来水、湖水及pH缓冲液中的光解动力学。高压汞灯下,乙烯菌核利在重蒸水中的光解半衰期约为28 m in,而在太阳光下为3.86 h。自来水和湖水中溶解性物质对乙烯菌核利在高压汞灯下的光解动力学仅有微弱的淬灭效应,但在太阳光下表现出显著的敏化效应,照光3 h的敏化效率分别为138%和126%。2种光源下,pH 5.0和pH 7.0缓冲液对乙烯菌核利的光解均表现为光淬灭效应,高压汞灯照光60 m in的淬灭效率分别为69%和57%,太阳光照光7 h的淬灭效率分别为77%和33%;pH 9.0缓冲液则表现出显著的敏化效应,高压汞灯照光20 m in的敏化效率为58%,而太阳光照光1 h的敏化效率则达到了415%。     

A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

UV photolysis and UV based advanced oxidation processes (AOPs) are gaining more and more attention for drinking water treatment. Quantum yield (ø) and molar absorption coefficient (ε) are the two critical parameters measuring the effectiveness of photolysis of a compound. The product of the two was proposed as a fundamental measure of a constituent’s amenability to transformation by photolysis. It was shown that this product, named the photolysis coefficient, k _p , can be determined using standard bench tests and captures the properties that govern a constituent’s transformation when exposed to light. The development showed the photolysis coefficient to be equally useful for microbiological, inorganic and organic constituents. Values of k _p calculated by the authors based on quantum yield and molar absorption coefficient data from the literature were summarized. Photolysis coefficients among microorganisms ranged from 8500 to more than 600000 and are far higher than for inorganic and organic compounds, which varied over a range of approximately 10 to 1000 and are much less sensitive to UV photolysis than the microorganisms.     

丁虫腈在环境中的降解特性

采用室内模拟试验研究丁虫腈在水体中的光解、水解及其在3种不同类型土壤中的降解特性。结果表明,丁虫腈在酸性和中性条件下比较稳定,不易水解,而在碱性条件下水解较快,在50℃、pH值为9．0的缓冲溶液中降解半衰期为26．7d。通过对水解产物的鉴定,推断丁虫腈的水解机理为碱催化水解。在[光]照度为2500lx、紫外强度为25I．LW·cm-2的人工光源氙灯条件下,丁虫腈的降解半衰期为1．5h,主要降解产物为氟虫腈。丁虫腈在太湖水稻土、江西红壤和陕西潮土中培养180d后均未发生明显降解,表明该农药在土壤中较难降解。     

紫外辐射与生物膜同步耦合降解喹啉

紫外辐射光解与生物降解同步耦合的气升式内循环反应器用于喹啉的降解.实验过程中分别采用单独紫外光解、单独生物降解和紫外光解与生物降解同步耦合的方法对喹啉进行降解.结果表明,喹啉在紫外光解与生物降解同步耦合的作用下,其降解速率明显提高.喹啉降解动力学分析结果表明,喹啉的生物降解可以用有抑制性的Haldane模型描述.相比生物降解过程,单独紫外光解对喹啉的降解速率可以忽略,但将紫外辐射与生物降解耦合在一起后,可以提高喹啉的最大降解速率近1倍并减小抑制常数36%,同时还可以提高喹啉的矿化程度.     

A study of the atmospheric reaction of CH3S with O3 as a function of temperature

The atmospheric reaction of the methylthiyl radical (CH₃S) with O₃ was investigated as a function of temperature (259–381 K), in the pressure range of 25–300 Torr, using the technique of laser photolysis/laser-induced fluorescence. The resulting Arrhenius expression, with an uncertainty of ±2σ, was k₁(T=259–381 K)=(1.02±0.30)×10⁻¹² exp[(432±77) K/T] cm³ molecule⁻¹ s⁻¹. The obtained rate constant k₁ was independent of pressure over the limited range employed. Our results are compared with the previous studies carried out, at single temperature and as a function of temperature, by different techniques.     

Photochemical behaviour of musk tibetene

BACKGROUND: Synthetic musk compounds are widely used as additives in personal care and household products. The photochemical degradation of musk tibetene in aqueous solutions or in acetonitrile/water mixtures under different conditions was studied in order to assess its environmental fate. METHODS: Musk tibetene dissolved (or suspended) in water and/or acetonitrile/water mixtures was irradiated at different times by UV-light and by solar light. The irradiation mixtures were analyzed by NMR and TLC. The photoproducts formed were identified by GC-MS and NMR data. RESULTS: The experimental results indicated that musk tibetene was photodegradable in water or acetonitrile/water mixtures with half-life reaction times close to 20 minutes. The irradiation mixtures were separated by chromatographic techniques yielding three photoproducts (3,3,5,6,7-pentamethyl-4-nitro-3H-indole, 3,3,5,6,7-pentamethyl-4-nitro-1H-indoline and 3,3,5,6,7-pentamethyl-4-nitro-3H-indolinone) identified by means of spectroscopic analysis. DISCUSSION: The numerical modelling of the photodegradation concentration-time profiles gave (8.13 +/- 0.15) x 10(-2) and (1.34 +/- 0.04) x 10(-2) mol/E for the overall primary quantum yield of direct photolysis for musk tibetene and the major intermediate (3,3,5,6,7-pentamethyl-4-nitro-3H-indolinone), respectively, in the wavelength range 305-366 nm. The half-life times of photodegradation of the both substances varied from 1-1.5 hours at 20 degrees N during the summer season to 6-10 hours for highest latitudes in winter. CONCLUSIONS: Under solar light, musk tibetene was photolabile in acetonitrile and acetonitrile/water 1/1, while it was slowly degraded when suspended in water. In all media, musk tibetene was photodegraded into three photoproducts. By using a kinetic model, the overall primary quantum yields of direct photolysis of musk tibetene and its main photoproduct, in the wavelength range 305-366 nm, were estimated, indicating that the photodegradation rate for musk tibetene is faster than the photolysis rate of the major by-product. RECOMMENDATIONS AND PERSPECTIVES: The results indicate that, in order to assess the environmental impact of musk tibetene on the aquatic ecosystem, great attention should be focused on the major photoproduct which is proved to be more persistent than the parent compound under light irradiation. The predicted half-life times of direct photolysis for both substances ranged from 1-1.5 hours at 20 degrees N during the summer season to about 6-10 hours for highest latitudes in winter, indicating that, from a photochemical point of view, the environmental persistence of these substances increases by increasing the latitudes and during the cold seasons, making more realistic an intake of these xenobiotic molecules into the food chain of aquatic living organisms. Tanabe reports in his Editorial (Tanabe 2005) that "It is necessary to have knowledge of the global picture of synthetic musk pathways. So, it is conceivable that now is the time to study the transport, persistency, distribution, bioaccumulation and toxic potential of this new environmental menace on a global scale, especially in developing countries". Therefore, the future environmental analysis and investigations on the eco-toxicity of nitro musk compounds should take into account not only the presence of the parent compounds but also their photochemical intermediates or end-by-products.     

几种天然矿物去除苯酚效果及日光光解效应评价

本文以四种天然矿物为受试矿物,评价了它们去除苯酚的效果,以及日光光解放应及温度,ＰＨ值,矿物浓度,苯酚初始浓度对去除效果的影响。