Atmospheric and kinetic studies of OH and HO2 by the FAGE technique

A new FAGE setup has recently been built at the University of Lille, France. It permits the quantification of OH and HO₂ in the atmosphere with a detection limit of 3×10⁵ molecules/(cm³·min) for OH and 1×10⁶ molecules/(cm⁵·min) for HO₂. Its coupling to a photolysis cell enables the measurement of the total reactivity of the hydroxyl radical in ambient air and kinetic studies in laboratory. Two configurations have been considered: one with the photolysis cell at 90° to the FAGE nozzle, the other on line with the FAGE nozzle. The two configurations have been tested and validated by measuring the well known rate constants of OH with CH₄, C₃H₈ and CO. The advantages and drawbacks of each configuration have been evaluated. The “on line” configuration limits losses and permits measurements over a larger reactivity range but is affected by OH formation from the laser beam striking the FAGE nozzle, thus limiting the ability to carry out energy dependence studies which can, in contrast, be successfully performed in the 90° configuration.     

Toxic effects of chlortetracycline on maize growth, reactive oxygen species generation and the antioxidant response

The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied. The root and shoot lengths and fresh weights of maize seedlings were inhibited by CTC treatment (p < 0.05). Root length was more sensitive than other parameters with the EC₁₀ value of 0.064 mg/L. The spin trapping technique followed by electron paramagnetic resonance (EPR) analysis was used to quantify the ROS production. The ROS generated in maize roots after exposure to CTC was identified as hydroxyl radical (.OH). The EPR signal intensity correlated positively with the logarithm of CTC concentrations exposed (p < 0.05). The dynamic changes of malondialdehyde (MDA) contents and the antioxidative enzyme activities in maize roots were also determined. As compared to the control group, CTC was found to significantly increase MDA content. Treatment of maize roots with the.OH scavenger sodium benzoate (SB) reduced the MDA content and enhanced the antioxidative enzyme activities. The results demonstrated the harmfulness of CTC at high dose to maize in the early developmental stage, and clarified that the inducement of.OH is one of the mechanisms of CTC toxicity.     

上海市城区VOCs的年变化特征及其关键活性组分

2010年在上海市城区开展了为期一年的连续观测,采用自动在线GC-FID方法定量测试了大气中56个VOCs物种的浓度.结果发现,上海市城区大气VOCs的全年小时体积分数为(2.47~301.48)×10^-9,平均体积分数为(26.45±23.36)×10^-9,其中,烷烃占46.72%,芳香烃占33.18%,烯烃占11.33%,乙炔占8.76%.T/B(甲苯/苯)为3.51±2.40,表明气团除受机动车影响外,受溶剂、油气和LPG挥发等其他VOCs排放的影响也比较突出;E/E(乙烷/乙炔)为0.98±0.68,表明气团存在老化现象,且春冬季节气团光化学年龄相对较短,夏秋季节光化学年龄相对较长.VOCs的浓度水平和组成在不同风向风速影响下存在一定差异,西南部石化和化工企业排放的VOCs对城区的影响明显,其主要物种为芳香烃和烯烃;该地区气团的OH消耗速率常数(K^OH)为8.05×10^-12 cm³·分子^-1·s^-1,平均VOCs最大O₃增量反应活性(4.00 mol·mol^-1)与乙烯相当,平均反应活性较强;对OH消耗速率(L^OH)贡献率最大的是烯烃(42.21%)和芳香烃(40.83%),对臭氧生成潜势(OFP)贡献率最大的是芳香烃(62.75%)和烯烃(21.70%),VOCs的关键活性组分是二甲苯、甲苯、乙苯、乙烯、丙烯、反-2-丁烯及异戊二烯.     

Unique products from the reaction of naphthalene with the hydroxyl radical

Many of the products of the reaction of naphthalene (Naph) with the OH radical in a reaction chamber were identified. Previously unidentified products included 1,2-naphthoquinone (NQ), oxygenated indenes and benzopyrones. Possible pathways for the formation of 1,2-NQ and 1,4-NQ are proposed. In the chamber reactions, more 1,2-NQ than 1,4-NQ partitioned to the particle phase. From this result we infer that, in the atmosphere, the percentage of 1,2-NQ in the particle phase should be greater than that for the 1,4-NQ. Because both of these compounds are considered to be toxic, and since they appear in both the gas and particle phases in the reaction chamber, and by implication in the atmosphere, it is considered important that both the gas and particle phases of these two compounds should be measured to assess their impact on human health.     

Diatomaceous silica filter aid filtration for the effectiveseparation of colloidal Cr(OH)3 precipitatefrom tanning wastewater

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Reaction mechanism of 3-chlorophenol with OH, H in aqueous solution

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈｌｏｒｏｐｈｅｎｏｌｓａｒｅｒａｎｋｅｄｈｉｇｈａｍｏｎｇｐｏｌｌｕｔａｎｔｓｉｎｔｈｅｅｎｖｉｒｏｎｍｅｎｔｏｗｉｎｇｔｏｔｈｅｉｒｈｉｇｈｔｏｘｉｃｉｔｙ ,ｓｔｒｏｎｇｓｔｅｎｃｈ ,ａｎｄｈｉｇｈｓｏｌｕｂｉｌｉｔｙｉｎｗａｔｅｒ.Ａｓｆａｒａｓｍｏｎｏ ｃｈｌｏｒｏｐｈｅｎｏｌｓａｒｅｃｏｎｃｅｒｎｅｄ ,ｔｈｅｒｅａｒｅｔｈｒｅｅｉｓｏｍｅｒｓ:ｏｒｔｈｏ ,ｐａｒａ ａｎｄｍｅｔａ .Ｉｔｗａｓｒｅｐｏｒｔｅｄｔｈａｔｔｈｅｉｓｏｍｅｒｓｈａｖｅｓｉｍｉｌａｒｔｏｘｉ…     

La-Cu-O/γ-Al2O3催化剂上CO和CH4氧化活性及氧性质研究

用长光路ＦＴＩＲ技术研究氟里昂替代物ＨＦＣ１５２ａ（ＣＨ３ＣＨＦ２）和ＨＣＦＣ２２（ＣＨＣｌＦ２）与ＯＨ自由基的大气光化学反应，研究了反应产物和反应机理，并对它们的环境影响和工业应用前景进行了评价．ＨＣＦＣ２２只能作为过渡性的替代物使用，而ＨＦＣ１５２ａ可以发展成为非常有价值的永久性替代物．     

钙化物对HCl的脫除动力学研究

采用热重法对氢氧化钙在空气下脱除HCl过程进行了研究，结果表明，钙化物脱氯的最佳温度为600～700℃．钙化物脱氧过程为一级反应．钙化物脱氯的动力学行为可用收缩核模型加以表征．钙化物脱氯的过程存在控制段的转移．反应初期化学反应占主导地位，但随着反应的进行，逐渐受产物层的扩散控制.表面反应活化能及固体扩散活化能分别为58.8kJ/mol及105.73kJ/mol．     

Catalytic ozonation of reactive red X-3B in aqueous solution under low pressure: decolorization and OH· generation

Catalytic ozonation of Reactive Red X-3B in aqueous solution had been carried out in an ozone oxidation reactor where Mn-Fe-ceramic honeycomb was used as the catalysts. The presence of Mn-Fe-ceramic honeycomb catalyst could obviously improve the decoloration efficiency of Reactive Red X-3B and the utilization efficiency of ozone compared to the results from non-catalytic ozonation. Adsorption of Reactive Red X-3B had no obviously influence on the degradation efficiency. Addition of tert-butanol significantly decreased the degradation efficiency, indicating that the degradation of Reactive Red X-3B followed the mechanism of hydroxyl radical (OH·) oxidation. The operating variables such as reaction pressure and ozone supply had a positive influence on the degradation efficiency, mainly attributing to facilitate the ozone decomposition and OH· formation.     

水中无机氮形态变化对酮洛芬光降解的影响

研究了模拟太阳光照射下水环境中不同形态氮(NO₃^-、NO₂^-和NH₄⁺)对酮洛芬(KET)光解的影响.结果表明,KET在平均波长(200~450nm)下量子产率Φ_o为0.14. NO₃^-浓度从0.01mmol/L^-增至1.0mmol/L时, KET光解速率常数从0.0109降至0.0085; NO₂^-浓度从0.01mmol/L增至1.0mmol/L时, KET光解速率常数从0.0095降至0.0069, NH₄⁺对KET的光解基本无影响. NO₃^-的光掩蔽现象对KET光解的影响起主要作用; NO₂^-则通过光掩蔽现象和羟基自由基猝灭来抑制KET的光解.同时研究了当水环境中pE值发生变化而引起水中无机氮形态转化时,不同形态氮共存对KET光解的复合影响,随着pE值的增大,KET的光解速率先减小后增大;当NO₂^-和NH₄⁺共存时,两者对KET光解的影响存在拮抗作用,这一拮抗作用也存在于NO₂^-和NO₃^-之间.