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排序方式: 共有452条查询结果,搜索用时 15 毫秒
411.
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Yanyu Wu Shaoqi Zhou Fanghui Qin Huaping Peng Yanglan Lai Yiming Lin 《Process Safety and Environmental Protection》2010,88(4):276-284
In this study, chemical oxygen demand (COD) was characterized as total organic constituents and the isolated humic substances (HS) were characterized as an individual organic contaminant in landfill leachate. It was found that the HS content of landfill leachate was 83.3%. The results of laboratory tests to determine the roles of HS in reducing the organic content of landfill leachate during Fenton process are presented. Furthermore, the performances of oxidation and coagulation of Fenton reaction on the removal of HS and COD from leachate were investigated. The change curves of HS removal were similar to those of COD. The HS removal was 30% higher than COD removal, which indicated that HS were mostly degraded into various intermediate organic compounds but not mineralized by Fenton reagent. The oxidation removal was greatly influenced by initial pH relative to the coagulation removal. The oxidation and coagulation removals were linear dependent with hydrogen peroxide and ferrous dosages, respectively. Ferrous dosage greatly influenced the coagulation removal of COD at low ratio ([H2O2]/[Fe2+] < 3.0), but not at extremely high ratio ([H2O2]/[Fe2+] > 6.0). The coagulation removal of HS was not affected obviously by oxidation due to both Fenton oxidation and coagulation remove high molecular weight organics preferentially. Higher temperature gave a positive effect on oxidation removal at low Fe2+ dosage, but this effect was not obvious at high Fe2+ dosage. 相似文献
413.
Chang-Mao Hung Wen-Liang Lai Jane-Li Lin 《Frontiers of Environmental Science & Engineering》2013,7(3):428-434
This work describes the environmentally friendly technology for oxidation of ammonia (NH3) to form nitrogen at temperatures range from 423K to 673K by selective catalytic oxidation (SCO) over a nanosized Pt-Rh/γ-Al2O3 catalyst prepared by the incipient wetness impregnation method of hexachloroplatinic acid (H2PtCl6) and rhodium (III) nitrate (Rh(NO3)3) with γ-Al2O3 in a tubular fixed-bed flow quartz reactor (TFBR). The characterization of catalysts were thoroughly measured using transmission electron microscopy (TEM), threedimensional excitation-emission fluorescent matrix (EEFM) spectroscopy, UV-Vis absorption, dynamic lightscattering (DLS), zeta potential meter, and cyclic voltammetry (CV). The results demonstrated that at a temperature of 673K and an oxygen content of 4%, approximately 99% of the NH3 was removed by catalytic oxidation over the nanosized Pt-Rh/γ-Al2O3 catalyst. N2 was the main product in NH3-SCO process. Further, it reveals that the oxidation of NH3 was proceeds by the over-oxidation of NH3 into NO, which was conversely reacted with the NH3 to yield N2. Therefore, the application of nanosized Pt-Rh/γ-Al2O3 catalyst can significantly enhance the catalytic activity toward NH3 oxidation. One fluorescent peak for fresh catalyst was different with that of exhausted catalyst. It indicates that EEFM spectroscopy was proven to be an appropriate and effective method to characterize the Pt clusters in intrinsic emission from nanosized Pt-Rh/γ-Al2O3 catalyst. Results obtained from the CV may explain the significant catalytic activity of the catalysts. 相似文献
414.
The occurrence of tributyltin (TBT) is reported in the coastal waters of a few selected sites in Peninsular Malaysia. Water, bivalves and sediment samples collected were analysed specifically for TBT using sensitive analytical methods which involved a solvent extraction procedure with appropriate clean-up followed by graphite furnace atomic absorption spectrometric measurements. The levels of TBT in the seawater in unexposed areas were found in the range from <3.4 to 20 ng litre(-1) as compared to coastal areas with high boat and ship activities where TBT levels in seawater were generally above 30 ng litre(-1), with the highest level found at 281.8 ng litre(-1). TBT levels in the tissues of random cockle and soft-shell clam samples from local markets were found in the range from <0.5 to 3.7 ng g(-1) wet weight. The levels of TBT found in green mussel samples both from the market (23.5 ng g(-1) wet weight) and those from a mussel farm (14.2 ng g(-1) wet weight) indicate slight accumulation of TBT. In sediments, TBT levels were found ranging from <0.7 ng g(-1) dry weight in unexposed coastal sites to as high as 216.5 ng g(-1) dry weight for a site within a port area. 相似文献
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直角拐弯通道中空气冲击波的传播及数值模拟 总被引:8,自引:0,他引:8
针对地下通道中空气冲击波的传播,通过试验研究,得到了空气冲击波在直角拐弯通道中传播的衰减系数.同时,应用流体网格法进行了数值模拟,获得了通道直角拐弯前后空气冲击波传播的波形图和流场图.并将两方面的研究成果进行了对比,证明了试验和数值研究方法及研究成果的一致性. 相似文献
417.
The paper describes the study of the hydrodynamic and transport features of the S. Gilla lagoon in Sardinia, Italy. The study,
aimed at assessing the environmental quality of the water body, involved extensive use of numerical models based on the shallow
water equations, thus enabling to simulate a number of different situations of practical interest. Based on field data, six
meteorological and hydrologic patterns were recognised which were assumed as representative of the various conditions occurring
in the four seasons. Typical winter conditions proved effective for the water refreshment, while the other seasonal patterns
induced a stronger internal mixing. Thus, unfavourable salinity distributions with respect to the fish farm activities, which
are carried out in the water body, were obtained with the winter pattern, whereas, on the other hand, a higher dilution of
pollutants discharged by the river inflows was achieved. In general, between dominant winds, southeast winds proved more effective
in forcing internal mixing than northwest winds. Two flood events with quite different return periods were also simulated,
in order to estimate the extent of the inundated areas and the salinity depletion. The consequent salinity recovery was simulated
both in natural conditions and with the discharge of salt sea water into the lagoon to accelerate the salinity re‐equilibrium.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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