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Photodegradation of 17α-ethynylestradiol in nitrate aqueous solutions
Dong Ren,Tingting Bi,Shumei Gao,Xukun Li,Bin Huang,Xuejun Pan 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.2
17α-Ethynylestradiol (Ee₂) has gotten growing concerns due to its widely detected in the environment and high estrogenic potency. However, the knowledge on the photochemical behaviors of Ee₂ in natural waters is still limited. Herein, the photodegradation and estrogenic potency variation of Ee₂ induced by nitrate were studied using a sunlight simulator consisted by a 300 W medium pressure mercury lamp and 290 nm cut-off filters. It was found that Ee₂ could be photodegraded at a rate of 0.0193 h-1 in pure aqueous solutions, and the photodegradation of Ee₂ could be significantly promoted by nitrate. The photodegradation removal rate of Ee₂ was increased from 9% in Milli-Q water to 85% in 2.0 mM nitrate solutions. Reactive species scavenging experiments demonstrated that the photogenerated HO? contributed about 55% to Ee₂ degradation. Fe(III), Cl- and dissolved humic acid (DHA) could inhibit the photodegradation of Ee₂ by competing the incident light and photogenerated HO?, while HCO₃ - had no influence on Ee₂ photodegradation. Ee₂ was determined to be phototransformed into organic chemicals without estrogenic potency by GC-MS and MCF-7 cell proliferation toxicity tests. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens and provide information for ecological risk assessment.
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Spatiotemporal Variations and Possible Sources of Ambient PM10 from 2003 to 2012 in Luzhou, China
Dong Ren,Youping Li,Hong Zhou,Xiaoxia Yang,Xiaoman Li,Xuejun Pan,Bin Huang 대한환경공학회 2014 Environmental Engineering Research Vol.19 No.4
Descriptive statistics methods were used to study the spatiotemporal variations and sources of ambient particulate matter (PM10) in Luzhou, China. The analyzed datasets were collected from four national air quality monitoring stations: Jiushi (S1), Xiaoshi (S2), Zhongshan (S3), Lantian (S4) over the period of 2003-2012. This city was subjected serious PM10 pollution, and the long-term annual average PM10 concentrations varied from 76 to 136 μg/m3. The maximum concentration was more than 3-fold of the annual average (40 μg/m3) issued by EPA-China for the ambient air quality. General temporal pattern was characterized by high concentrations in winter and low concentrations in summer, and general spatial gradient was in the reduction order of S2 > S4 > S3 > S1, which were both due to different particulate contributors and special meteorological conditions. The source apportionment indicated that vehicular emissions, road dusts, coal burning and chemical dusts were the major contributors of the identified PM10 pollution, and the vehicular emissions and the road wear re-suspended particles dominated the heavy PM10 pollution in recent years. Two other potential sources, agricultural and celebration activities could decrease the air quality in a short term. Finally, some corresponding suggestions and measures were provided to improve the air quality.
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Jing Guo,Ligang Liu,Yunli Feng,Sha Liu,Xuejun Ren,Qingxiang Yang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.2
In this work, the morphology and structures of the eutectic and secondary carbides in a new high chromiumFe-12Cr-2.5Mo-1.5W-3V-1.25C designed for cold-rolling work roll were systematically studied. The precipitatedcarbides inside the grains and along the grain boundaries were investigated with optical microscope,scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy andX-Ray diffraction. Selected area diffraction patterns have been successfully used to identify the crystal formationand lattice constants of the carbides with different alloying elements. The results show that the eutectic carbidesprecipitated contain MC and M2C distributed along the grain boundaries with dendrite feature. The compositionand crystal structure analysis shows that the eutectic MC carbides contain VC and WC with a cubic and hexagonalcrystal lattice structures respectively, while the eutectic M2C carbides predominantly contain V2C and Mo2Cwith orthorhombic and hexagonal crystal lattices respectively. The secondary carbides contain MC, M2C,M7C3 formed along the grain boundaries and their sizes are much larger than the eutectic carbides ones. The secondary M23C6 is much small (0.3-0.5μm) and is distributed dispersively inside the grain. Similar tothe eutectic carbides, the secondary carbides also contain VC, WC, V2C, and Mo2C. M7C3 is hexagonal(Fe,Cr)7C3, while M23C6 is indexed to be in a cubic crystal form.
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