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Photo-responsive adsorption-photocatalysis nanocomposites are generally used in water and wastewater decontamination; however, the prolonged adsorption capacity of composites and the role of adsorption in concomitant photocatalysis are typically neglected. These composites can be regenerated under light irradiation as their adsorption capacity decreases. Herein, a novel adsorption-photocatalysis bifunctional nanocomposite, Bi-doped TiO2 supported on powdered activated carbon (Bi2O3/TiO2/PAC), was prepared using the sol-impregnation-hydrothermal procedure. Bi2O3/TiO2/PAC with a secondary calcination temperature of 700°C under a nitrogen atmosphere was selected for maximum adsorption capacity on Methyl Orange (MO). The composite displayed an excellent adsorption capacity and was easily separated and recycled. The results demonstrate that 71.2% photocatalytic regeneration efficiency could be attained under visible light irradiation for 1 hr at an intensity of 750?W/m2 and pH 7. Characterization of the as-prepared Bi2O3/TiO2/PAC nanocomposite (700°C) indicates that it possesses a highly specific surface area and great optical properties, showing bifunctional adsorption-photocatalysis characteristics. The p-n heterojunction of the composite played a dominant role in the photocatalytic regeneration process, and effective degradation of MO could be achieved along with composite regeneration. 相似文献
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The sensitivity of Chinese soybean cultivars to ambient ozone(O3) in the field is unknown,although soybean is a major staple food in China. Using ethylenediurea(EDU) as an O3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40(accumulated O3 over an hourly concentration threshold of40 ppb) over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O3 and ranked the cultivars from very tolerant( 10% change) to highly sensitive( 45% change), which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O3-tolerant cultivars in China, while strategies for implementing control measures of regional O3 pollution are being implemented. Overall, these results suggest that present ambient O3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food. 相似文献
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再生水具有就近易得、水量大且稳定等突出优点,已成为景观水体的重要补给水源。但再生水中含有氮、磷等营养物质,景观回用过程中可能会加剧藻类水华爆发风险。在藻类生长的早期阶段,采用紫外线处理有可能将再生水中藻类生物量控制在低风险范围,从而预防再生水景观回用水体中发生水华。以深圳市某污水处理厂二级出水为再生水回用景观水体的典型样品,考察了紫外线(254 nm波段)对典型微藻斜生栅藻的生长抑制效果,采用流式细胞术、调制荧光技术等方法,研究了不同紫外剂量对斜生栅藻的生长抑制效果,以及对藻细胞膜完整性和光合活性的影响。结果表明:对于初始密度约为7×104个/m L的斜生栅藻,50~100 m J/cm2的紫外线能够取得1~5 d的生长抑制期,150~200 m J/cm2剂量能将生长抑制期延长至10 d。紫外线能迅速引起斜生栅藻光合活性下降并能逐渐引起部分藻细胞破裂,100~200 m J/cm2剂量处理后10 d内膜损伤细胞比例达到16%~71%。可见,紫外线能够对再生水中的斜生栅藻取得显著的生长抑制效果,是具有应用前景的景观水体水华风险防控手段。 相似文献
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Min Yang Ashraful Islam Guangxi Sun Ayman N. Saber Wei Shang Xingcan Zheng Yu Zhang 《环境科学学报(英文版)》2022,34(12):174-183
This study provided insights into the persistent yellowish color in biological and tertiary effluents of municipal wastewater through a multi-characterization approach and fluorescence excitation-emission matrix-parallel factor (EEM-PARAFAC) analysis. The characterization was performed on three to five full-scale municipal wastewater treatment plants (WWTPs), including differential log-transformed absorbance (DLnA) spectroscopy, resin fractionation, size-exclusion chromatography for apparent molecular weight analysis (SEC-AMW), and X-ray photoelectron spectroscopy (XPS) analysis. Hydrophobic acids (HPOA) were abundant in visible colored dissolved organic matter (DOM). The SEC-AMW result showed that the molecular weight of the colored substances in the secondary effluents is mainly distributed in the range of 2–3 kDa. Through XPS analysis, C-O/C-N and pyrrolic/pyridonic (N-5) were found to be positively correlated with chroma. PARAFAC component models were built on biological (two components) and tertiary effluent (three components) and the correlation analysis revealed that PARAFAC component 2 in biological effluent (BE-C2) and component 1 in tertiary effluent (TE-C1), which were ascribed to Hydrophobic acids and Humic acid-like, were the responsible visible colored DOM components cause yellowish color. In addition, component similarity testing found that the identified visible colored DOM PARAFAC BE-C2, and PARAFAC TE-C1 were identical (0.96) in physicochemical properties, with 4% removal efficacy on average, compared with 11% for invisible colored DOM. This implied that tertiary effluents containing colorants (TE-C1) were resistant to degradation/removal using different disinfection and filtration processes in advanced treatments. This sheds light on many physicochemical aspects of PARAFAC-identified visible colored DOM components and provides spectral data to build an online monitoring system. 相似文献
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论战略环境评价中的公众参与 总被引:31,自引:0,他引:31
介绍了公众参与对于战略环境评价 ( SEA)的意义 ;着重分析了 SEA中公众参与实施的关键环节 :即公众参与者界定 ,公众参与内容 ,公众参与时机 ,公众参与方式及公众参与反馈信息处理 ,并阐述了 SEA中公众参与的局限性。 相似文献
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