臭氧与二乙胺和三乙胺气相反应的速率常数

利用自制的烟雾箱系统研究了臭氧与二乙胺和三乙胺的气相反应动力学. 实验过程中保证二乙胺和三乙胺浓度远远大于臭氧浓度, 使得实验在准一级条件下进行. 加入环己烷以消除实验过程中可能产生的OH自由基对反应的影响. 在(298±1) K和1.01×105 Pa条件下, 测得臭氧与二乙胺和三乙胺反应的绝对速率常数值分别为(1.33±0.15)×10^-17和(8.20±1.01)×10^-17 cm³·molecule^-1·s^-1. 与文献中已有的其它胺类的臭氧反应数据比较后发现, 臭氧与胺的反应可以用亲电反应机制来解释. 另外, 通过对比发现, 臭氧与三取代的烷基胺类的反应速率要远远大于其与二取代的烷基胺类的反应速率. 这在一定程度上可有助于解释外场观测到的气溶胶相中二烷基胺盐较多的事实. 利用测得的速率常数和大气中臭氧浓度, 还估算了二乙胺和三乙胺与臭氧反应的大气寿命. 结果显示, 与臭氧的反应是二乙胺和三乙胺在大气中的一种重要的消除途径, 尤其是在污染严重地区.     

Studies on Oxidants' Generation in a Foaming Column with a Needle to Dielectric Covered Plate Electrode

The generation of oxidative products in the newly investigated foaming system was improved by a discharge between a high voltage multineedle electrode and a dielectric covered plate electrode. A uniformity of the discharge was observed. The presence of alumina dielectric seems to be responsible of the homogenous spatial distribution of the discharge. The absolute power and energy of the discharge was determined. Besides, in larger gap space the foam quality was improved.This way of oxidant's generation, which might be prospective for the treatment of exhaust gas and wastewater, has not been investigated by the other researchers' groups as yet. During the laboratory test 875 ppm of gaseous ozone, 0.5 mg/l of dissolved ozone and 62 mg/l of hydrogen peroxide was obtained at 14 kV of applied voltage and 5 l/min of oxygen gas flow in the present configuration used for the discharge generation. The average yield of gaseous ozone production ranged 55 gO₃/kWh.     

玻璃纤维表面的乙烯基单体接枝聚合

用玻璃纤维表面处理剂ＭＡＣ处理玻璃纤维后，再进行臭氧处理，使玻璃纤维的表面产生活性中心，引发苯乙烯、甲基丙烯酸甲酯、及丙烯酸等乙烯基单体在玻璃纤维表面上接枝聚合。接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上接枝聚合物的存在。     

Nonempirical Description of the Atmospherically Important Anionic Species. II. Hydrated Ozone Anions

Ozone–water clusters are nonempirically modeled in the complete active space self-consistent field approximation (CASSCF) with the energetic estimates obtained at the multiconfiguration quasidegenerate perturbation theory level (MCQDPT) with 6–31++G** basis set. Coordination of a neutral ozone molecule to small water clusters is either surface or interior, with the binding energy of the order of a weak hydrogen bond. Upon localization of an excess electron, the hydration of ozone becomes strong. The adiabatic affinities of water–ozone clusters and the energies of electron detachment from their anions, depending on the number of water molecules, estimate the electron hydration and vertical electron detachment thresholds of water or ice that superficially coordinates minor amounts of ozone.     

A nanometer-ZnO catalyst to enhance the ozonation of 2,4,6-trichlorophenol in water

Removal of 2,4,6-trichlorophenol (TCP) from water has been accomplished through zinc oxide (ZnO) catalytic ozonation. In the presence of ZnO catalyst, aqueous ozone (O₃) can be described by a two-stage behavior, first involving a short-term rapid decomposition followed by a second slow decomposition. The low reaction rate (k_d2) of second stage for O₃-ZnO systems suggested that most of O₃ was transferred into OH radical by ZnO catalyst and was rapidly consumed during the first stage. The combined use of O₃ and ZnO catalyst leads to a conspicuous 99.8% of TCP conversion in 30 min which compares favorably to the hardly 75% reached in the absence of the catalyst. The high reactivity of hydroxyl radicals that were generated by O₃-ZnO during the oxidation process effectively degraded TCP. Without regard to the O₃ dose, the catalytic–oxidation kinetics of the process depends on the concentration of ZnO catalyst and size of ZnO particles. At the same concentration of three different ZnO size in batch tests, TCP degradation rates were in the order of nanometer > submicrometer > micrometer. The effect of pore diffusion on the rate of TCP–ZnO reactions was determined by examination of the effectiveness factor using different particle sizes of ZnO. Calculations show that the rate of TCP decomposition by nano-size ZnO was strongly controlled by surface reaction with little influence of pore diffusion, as indicated by the high effectiveness factors.     

Ozone production and de-NO x modeling in dry air electrical discharges

Numerical simulations are performed to assess the possibility of using different kinds of electrical discharges operating in dry air under normal conditions as ozone generators. The ozone production and NO_x destruction efficiency are investigated as a function of discharge parameters such as the reduced electric field, the energy deposition, and the electron density. The specific energy deposition becomes a key parameter to compare the different classes of ozonators. During the operative phase the electric discharge produces an appreciable amount of nitrogen oxides. Taking into consideration both the active phase of flue gas processing and the post-discharge phase it is possible to achieve a good NO_x-removal efficiency even for initial concentrations as high as 1000 ppm. The main processes and characteristic times are discussed.     

Long-term trend in aerosol optical depth from 1980 to 2001 in north China

Using the Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical depth （AOD） at 500 nm data from 1980 to 2001 in north China, the spatial and temporal variations of AOD were examined. Seasonal AODs in Taklimakan Desert were 0.69 and 0.44 in spring and summer, respectively, which were mainly due to frequent occurrences of dust events in this region. Dust activities in spring also led to high aerosol loading in Gobi Desert and in northeast China where spring AODs were 0.33 and 0.29, respectively. Heavily impacted by events such as volcano eruption, forest fires and extraordinary dust storms, AODs showed large inter-annual variations. A decreasing tendency in AOD was observed in north China during 1980-1991, though a reverse tendency was revealed during 1997-2001, especially for spring AOD in northeast China. Further study is required to figure out how much human activities have contributed to the AOD tendency in north China.     

Ozone,chemical reactivity and biological functions

Various aspects of the structure, the reactivity in organic synthesis, in the atmosphere, in environment, in biology of ozone are described. Emphasis is placed on the relation with singlet oxygen and dihydrotrioxide.     

Concentration measurements of ozone in the 1200-300ppbv range: an intercomparison between the BNM ultraviolet standard and infrared methods

Simultaneous ultraviolet (UV) and infrared (IR) measurements of ozone concentration in air in the 1200-300 ppbv range have been performed using the ultraviolet absorption in the Hartley band at 0.2537 microm and the infrared absorption of a doublet at 9.507 microm in the nu(3) vibration-rotation band. Infrared concentration measurements were achieved using the tunable diode laser spectrometer of LPMA in Paris with interferometric control of the emitted wavelength while the UV concentration measurements were performed with the 49PS Megatec ozone generator of the Bureau National de Metrologie (BNM). The simultaneous recording of spectra of a reference cell filled with pure distilled ozone and of a low concentration mixture inside a long absorbing path Herriott cell allows to carry out infrared concentration measurements with an accuracy of the same order as the ultraviolet ones and provides the instrumental parameters of the spectrometer corresponding to each concentration measurement, which reduces systematic errors. Within the respective absolute uncertainties proper to the two techniques, no systematic discrepancy was evidenced between the IR and the UV measurements. The ozone ultraviolet absorption coefficient value determined by Hearn (308.3 +/- 4 cm(-1)atm(-1)) and used by the BNM and the National Institute of Standards and Technology (NIST) is confirmed by the present work.     

臭氧与二乙胺和三乙胺气相反应的速率常数

利用自制的烟雾箱系统研究了臭氧与二乙胺和三乙胺的气相反应动力学. 实验过程中保证二乙胺和三乙胺浓度远远大于臭氧浓度, 使得实验在准一级条件下进行. 加入环己烷以消除实验过程中可能产生的OH自由基对反应的影响. 在(298±1) K和1.01×105 Pa条件下, 测得臭氧与二乙胺和三乙胺反应的绝对速率常数值分别为(1.33±0.15)×10^-17和(8.20±1.01)×10^-17 cm³·molecule^-1·s^-1. 与文献中已有的其它胺类的臭氧反应数据比较后发现, 臭氧与胺的反应可以用亲电反应机制来解释. 另外, 通过对比发现, 臭氧与三取代的烷基胺类的反应速率要远远大于其与二取代的烷基胺类的反应速率. 这在一定程度上可有助于解释外场观测到的气溶胶相中二烷基胺盐较多的事实. 利用测得的速率常数和大气中臭氧浓度, 还估算了二乙胺和三乙胺与臭氧反应的大气寿命. 结果显示, 与臭氧的反应是二乙胺和三乙胺在大气中的一种重要的消除途径, 尤其是在污染严重地区.