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Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol(4-BP) by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH(6.1–10) and temperature, whereas inhibited by dissolved oxygen and organic solvents. The apparent activation energy was estimated to be 27.8 kJ/mol. The degradation mechanism and pathways of 4-BP were explored by employing N_2O and nitrate as the electron scavengers and liquid chromatography/mass spectrometry to identify the intermediates. 4-BP degradation proceeded via at least two pathways including direct photolysis and hydrated electron-induced debromination. The contributions of both pathways were distinguished by quantifying the quantum yields of 4-BP via direct photolysis and hydrated electron production in the system. 4-BP could be readily completely debrominated with all the substituted Br released as Br-, and the degradation pathways were also proposed. This study would shed new light on the efficient dehalogenation of brominated aromatics by using the UV/sulfite process. 相似文献
994.
Shuangshuang Xue Hongbo He Qizhe Fan Changlin Yu Kai Yang Weiya Huang Yang Zhou Yu Xie 《环境科学学报(英文版)》2017,29(10):70-77
A series of La/Ce-codoped Bi_2O_3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N_2 physical adsorption, X-ray powder diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), UV–Vis diffuse reflectance(UV–Vis DRS), Fourier transform infrared spectroscopy(FT-IR),photoelectrochemical measurements, and photoluminescence(PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi_2O_3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi_2O_3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi_2O_3 displayed much higher photocatalytic performance than that of bare Bi_2O_3, single La or Ce doped Bi_2O_3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons(e~-) and holes(h~+). 相似文献
995.
考洲洋水环境质量现状及受潮汐影响变化分析 总被引:1,自引:0,他引:1
文章应用单因子标准指数法、算术均值多因子指数法和营养状态指数法相结合的方法对当前考洲洋海域海水质量状况进行了评价,并依据考洲洋在潮汐涨、落情况下海水质量的变化,定量分析了考洲洋潮汐对其海水水质的影响。结果表明:磷酸盐、无机氮、石油类是影响考洲洋海域环境质量的主要因子,考洲洋内部海域均处于富营养化状态,总体水质状况为良好以下,潮水的涌入能改善考洲洋的水质状况,涨潮时期各航次的算术均值多因子指数之和比退潮时期平均降低了13.92%。且潮汐的变化对主要污染因子的影响顺序为:无机氮>磷酸盐>石油类,最后提出了考洲洋污染防治的对策和建议。 相似文献
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以某火电厂高架点源为例,运用AERMOD进行预测,对扇区进行粗划分和细划分,设置两组地表参数,分析SO2、NO2、PM10在敏感点的小时浓度、日均浓度和期间平均浓度最大值的差异.变化幅度分析方法表明,PM10的小时浓度、日均浓度、期间平均浓度最大值的变化幅度最大,NO2次之,SO2最小.高端值比较法分析表明,NO2小时浓度最大值的差异最大,SO2次之,PM10最小;NO2日均浓度最大值的差异最大,PM10次之,SO2最小;NO2期间平均浓度最大值的差异最大,SO2次之,PM10最小. 相似文献
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