大气中挥发性有机化合物小波分析方法探究

利用小波函数的分解重构从而得到可以反映大气环境中TVOC浓度变化趋势的图像,小波函数的分解就是将TVOC浓度数据分解为高频和低频两个部分,再分别将高频和低频部分重构,从而可得到反映大体变化趋势的低频部分和可以体现小波分析放大镜功能的高频部分。通过选取不同地区监测点位,包含不同环境特征,考虑不同行业,从而反应各类因素下不同时段,不同地区,不同特征TVOC浓度数据以反映不同城市TVOC浓度分布规律。     

大气中挥发性有机物监测和治理方法研究

为了有效监测、治理大气中的挥发性有机物,本文将展开相关研究。研究主要对大气挥发性有机物的危害与排放特点进行分析,然后依照挥发性有机物监测工作流程,对其中工作方法进行了论述,最终提出了挥发性有机物治理方法。通过本文研究,能够借助各种方法有效监测、治理挥发性有机物,提高大气环境质量,一定程度上解决相关污染问题。     

气相色谱法测定饮用水中挥发性卤代烃

利用大口径毛细管柱气相色谱／电子捕获检测器（GC／ECD）方法，直接进样测定了饮用水中三氯甲烷，四氯化碳，一溴二氯甲烷，二溴一氯甲烷，三溴甲烷五种挥发性卤代烃，所建立的方法简便，快速，灵敏度高，并具有较好的精密度与准确度，当五种卤代烃化合物的质量浓度平均值为9．03－20．19g/L,CV为2．9－7．5，标准差为0．3－0．9g/L，样品的加标回收率为80－118％，标准曲线的相关系数为0．998－0．999，ECD的温度为350℃，其最低检测限在0．1－0．7g/L范围内，。均低于文献报道值。     

吹扫捕集气相色谱质谱法测定水中5种挥发性卤代烃

建立了吹扫捕集与气相色谱/质谱联用测定水中5种挥发性卤代烃的分析方法。该方法的响应因子相对标准偏差均小于10%,其加标回收率在92%~110%之间,方法检出限介于0.01~0.20μg/L之间。该方法简便快捷、准确可靠,相比较其他环境样品分析前处理方法,环境友好,有着显著的优点,可广泛适用于饮用水源地及地下水中挥发性卤代烃的测定。     

挥发性卤代烃溶液标准物质短期稳定性研究

研究了挥发性卤代烃溶液标准物质短期稳定性。模拟运输过程中的环境温度和运输时间设计实验方案,重点研究高温因素对甲醇基体卤代烃溶液标准物质稳定性可能带来的影响。研究表明在模拟高温和低温极端的运输条件下,3种卤代烃混合溶液标准物质中涉及的10种卤代烃组分量值稳定,测量值与标准值最大偏差3%,在不确定度范围内。     

毛细管气相色谱法同时测定水中的7种挥发性卤代烃

本文采用毛细管气相色谱法进行同时测定饮用水中7种挥发性卤代烃的研究。实验表明,该方法前处理简单,测定方便,具有较好的灵敏度、准确度和精密度,结果令人满意。样品的加标回收率在90％～110％,相对标准偏差小于5％。     

室内空气中总挥发性有机物的热解吸气相色谱测定法

随着经济的发展进步,人们对空气质量的要求越来越高,本文是使用热解吸-毛细管柱气相色谱法测定室内的空气里挥发性有机化合物(也称TVOC)。测定方法:一般采取空气样本的办法是采用Tenax树脂来吸附,利用热解吸进样本空气,氢火焰离子化检测器以及HP-5毛细管柱分离检测。这样做的目的是为了快速分析室内空气挥发性有机物。这种方法被称为Tenax热解吸毛细管气相色谱法。这种测定方法适合环境空气中低浓度有机物的测定。     

水中挥发性卤代烃测定的不确定度评定

污水中挥发性卤代烃为国标优先检测项目之一,是污水检测的一个重要参考指标。为了提高挥发性卤代烃测量的准确度,对污水中4种挥发性卤代烃:三氯甲烷、四氯化碳、三氯乙烯、四氯乙烯进行测定,结果表明:不确定度主要来源于系统误差,建议尽量选用不确定度较小的标准溶液,误差较小的移液管和容量瓶,从而减小系统误差;且尽可能的进行多次重复测定,提高测量的精密度、准确度。     

室内空气中总挥发性有机物检验方法的改进

文章介绍了HP-5弱极性色谱柱代替非极性石英毛细管柱测定室内空气中的总挥发性有机物,并对该方法进行了包括标准曲线、精密度、回收率、准确度在内的验证性实验和空气样品的平行采样分析。通过对两种测定方法对比,HP-5弱极性色谱柱在精密度、回收率和准确度方面,都符合室内空气中总挥发性有机物国家标准分析的要求。该方法适合快速测定室内空气中总挥发性有机物的含量,具有快捷、成本低的优点。     

自动顶空气相色谱法快速测定饮用水中多种挥发性卤代烃

为建立快速测定饮用水中多种挥发性卤代烃的测定方法,采用DB-624毛细管色谱柱,自动顶空进样测定水中8种挥发性卤代烃,并对平衡时间、平衡温度进行研究和优化。用建立的方法对人工合成水样进行试验,每隔10min即可完成一个样品的测定。试验结果表明,水中8种挥发性卤代烃的平均加标回收率为90.5%～108.2%,相对标准偏差为1.82%～5.39%,最低检出限为0.10～0.50μg/L,对宁波市的二次供水样品的分析中有4种卤代烃检出。本研究所建立的方法简便、快速,在测定生活饮用水中多种挥发性卤代烃时具有较好的精密度与准确度。     

A Theoretical Study on the Mechanism and Kinetic of the Reaction between Ozone and Benzene

Ozone has been widely used to degrade volatile organic compounds (VOCs) in combination with other methods such as ultraviolet light, adsorption, thermal and catalytic incineration. Despite its fundamental importance, the mechanism and kinetics of the reaction between ozone and VOCs are still lacking of detailed investigation. It is well known that quantum chemical calculation is a well-established method for investigating the chemical reactions. In this paper, quantum chemical calculation is employed to investigate the mechanism and kinetics of the reaction between ozone and VOCs exemplified by benzene. The microcosmic reaction process was depicted and discussed in detail based on geometry optimizations made using the UB3LYP/6-31G (d) method. According to the mechanism study, the kinetic parameters were also calculated by the classical transition state theory (TST). The calculated activation energy is 14.90 kcal/mol at the QCISD(t)/6-311g(d,p)//UB3LYP/6-31G(d) level of theory, while the obtained Arrhenius expression is that, k=1.05×10¹¹ exp(-61527/RT) (cm³·mole^?1·s^?1). Both the activation energy and the Arrhenius expression are in good agreement with the experimental results, which indicated that the mechanism and kinetic study of the reaction between benzene with ozone by employing quantum chemical calculation was reasonable and reliable.     

应用模拟室内环境试验箱研究涂层有机挥发物的散发性

本研究以双组分溶剂型涂料形成涂层为代表试样,应用模拟室内环境试验箱,采用一次热解吸气相色谱法测定涂层有机挥发物的散发浓度,研究不同模拟试验条件(暴露面积、温湿度、光源、通风等)对被测涂层有机挥发物的散发性影响.研究发现被测涂层有机挥发物散发浓度随暴露面积、温度、湿度的增大明显增大,使用普通蓝荧光灯或365nm的UV-A...     

Fate of Organic Pollutants in a Full-Scale Drinking Water Treatment Plant Using O3-BAC

This research investigated the fate of organic pollutants in each unit of a full-scale O₃-BAC (biological activated carbon) drinking water treatment plant with micro-polluted raw water under different temperatures. Total organic matters were largely removed with low DBPs (disinfection by-products) formed. Large molecules were broken into smaller ones by O₃ and middle-sized ones totally removed. Concentration of polysaccharide decreased except under high temperature. Small molecule contaminant species of refractory industrial additives, hydrocarbons, aromatics, herbicides, possible DBPs, etc., were detected. Some species passed through treatment process, some were removed and also new species formed.     

The Role of Indole and Other Shikimic Acid Derived Maize Volatiles in the Attraction of Two Parasitic Wasps

After herbivore attack, plants release a plethora of different volatile organic compounds (VOCs), which results in odor blends that are attractive to predators and parasitoids of these herbivores. VOCs in the odor blends emitted by maize plants (Zea mays) infested by lepidopteran larvae are well characterized. They are derived from at least three different biochemical pathways, but the relative importance of each pathway for the production of VOCs that attract parasitic wasps is unknown. Here, we studied the importance of shikimic acid derived VOCs for the attraction of females of the parasitoids Cotesia marginiventris and Microplitis rufiventris. By incubating caterpillar-infested maize plants in glyphosate, an inhibitor of the 5-enolpyruvylshikimate-3-phospate (EPSP) synthase, we obtained induced odor blends with only minute amounts of shikimic acid derived VOCs. In olfactometer bioassays, the inhibited plants were as attractive to naive C. marginiventris females as control plants that released normal amounts of shikimic acid derived VOCs, whereas naive M. rufiventris females preferred inhibited plants to control plants. By adding back synthetic indole, the quantitatively most important shikimic acid derived VOC in induced maize odors, to inhibited plants, we showed that indole had no effect on the attraction of C. marginiventris and that M. rufiventris preferred blends without synthetic indole. Exposing C. marginiventris females either to odor blends of inhibited or control plants during oviposition experiences shifted their preference in subsequent olfactometer tests in favor of the experienced odor. Further learning experiments with synthetic indole showed that C. marginiventris can learn to respond to this compound, but that this does not affect its choices between natural induced blends with or without indole. We hypothesize that for naïve wasps the attractiveness of an herbivore-induced odor blend is reduced due to masking by nonattractive compounds, and that during oviposition experiences in the presence of complex odor blends, parasitoids strongly associate some compounds, whereas others are largely ignored.     

Novel developments in the multidimensional characterization of segmented copolymers

Controlled radical polymerization (CRP) provides the polymer chemist with the ability to produce tailor-made polymers with controlled molar masses, molar mass distributions, chemical compositions and macromolecular architectures. Segmented copolymers can be synthesized having polymer segments arranged in a linear fashion (linear block copolymers), however, polymer segments can also be attached to pre-synthesized macromolecules or to multifunctional core molecules to produce branched (graft) copolymers, polymer stars or dendrimers. Although there are many ways to control the chain growth and the architecture of the target macromolecules, side reactions cannot be completely avoided. Accordingly, even with CRP, obtained products exhibit chemical composition and topology distributions along with the molar mass distribution.