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891.
Guanglong Pang Donghui Wang Yunhong Zhang Chunyan Ma Zhengping Hao 《Frontiers of Environmental Science & Engineering》2016,10(3):447-457
MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples: coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ-MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene (DOM) and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained. 相似文献
892.
Wang Yuming Wang Yukun Chen Xiaohong Zhang Lidan 《Environmental science and pollution research international》2023,30(2):2721-2739
Environmental Science and Pollution Research - Heavy metal input from the coastal urbanization and industrialization and their potential ecological risks have been a great concern in the northern... 相似文献
893.
高层建筑竖井火灾中影响因素众多,并且各因素对高层楼梯井火灾中重要现象、关键数值等的影响大小不一,使得此类火灾中的实验或理论研究成本较高。通过建立全局敏感性分析平台,定量考察了高层楼梯井结构所涉及因素的影响大小,并能够方便地筛选掉对所考察量影响较小的因素,以降低实验或计算成本。使用数值模拟方法,通过CFD软件对包含阶梯几何框架的高层楼梯井结构火灾进行了共计60次工况计算。并且根据计算结果,使用全局参数敏感性分析方法,得出建筑尺寸、热释放速率、环境参数对高层楼梯井内烟气湍流特性及输运特性的敏感性排序。结果表明,火源热释放速率对各输出参数的影响均占38%以上。 相似文献
894.
Joshua W. Faulkner Zachary M. Easton Wei Zhang Larry D. Geohring Tammo S. Steenhuis 《Journal of environmental management》2010,91(8):1794-1801
Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash–Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods. 相似文献
895.
Chukwujindu M. A. Iwegbue Godwin E. Nwajei Jude E. Ogala Chukwudumebi L. Overah 《Environmental geochemistry and health》2010,32(5):415-430
The concentrations of trace metals (Cd, Pb, Cu, Cr, Fe, Ni, Zn and Co) were studied in soil profiles of eight municipal waste
dump sites in Warri metropolis. The results indicate that concentrations of trace metals varied widely among the different
dumpsites and decreased with depths in a studied soil profile. The accumulation pattern for the heavy metals in the soil profiles
follows the order: Fe > Pb > Mn > Co > Cr > Zn > Ni > Cu > Cd. The concentrations of metals found in these sites was below
the Canadian remediation criteria for land for agricultural, residential and commercial/industrial purposes except for the
cadmium levels in some sites that exceeded criterion values for agricultural and residential. In such sites, remedial actions
are required before any form of chosen development can take place. The levels of heavy metals found in these dump sites were
higher than that of the control site. The examined metals showed no significant correlation with soil physicochemical properties
at the surface horizon, which is suggestive evidence that these metals arise from anthropogenic input. 相似文献
896.
Environmentally Friendly Polyurethane Composites: Preparation, Characterization and Mechanical Properties 总被引:1,自引:0,他引:1
J. L. Zhang D. M. Wu D. Y. Yang F. X. Qiu 《Journal of Polymers and the Environment》2010,18(2):128-134
The waterborne polyurethane (PU) prepolymer was prepared based on isophorone diisocyanate (IPDI), polyester polyol (N220), dimethylol propionic acid (DMPA) and hydroxyethyl methyl acrylate (HEMA). The modified waterborne polyurethane–acrylate (PUA) emulsions were obtained with different proportions of acrylate (butyl acrylate and methyl methacrylate) and initiating agent by in situ dispersion technique. The structures and thermal properties of prepared PU and PUA were analyzed and characterized with FT-IR, UV–Vis spectroscopy and DSC. The PUA hybrid samples had lower glass transition temperature of hard segment and higher decomposition temperatures than PU sample. Performances of the emulsion and film were studied by means of apparent viscidity, particle size and polydispersity, surface tension and mechanical properties. The results indicated that the particle sizes of the PUA dispersions were larger than those of the pure PU and the solvent resistance, mechanical properties of PUA films was improved compare with the unmodified polyurethane film. The film had the biggest hardness and the least water absorption when the BA/MMA mass ratio 5:5 modified PU. The obtained PUA have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes. 相似文献
897.
Demetres Briassoulis Cyril Dejean Pietro Picuno 《Journal of Polymers and the Environment》2010,18(3):364-383
The critical review of norms and standards and corresponding tests to determine the compostability of biodegradable plastics,
possibly applicable also to biodegradable agricultural plastics, shows that many norms concerning testing and labelling of
compostable plastics have been established at the international level. Some of them are about plastic materials, some others
are about products like packaging. The media and conditions of testing cover mainly the conditions designed for industrial
composting facilities, and only a few concern home composting conditions. Considering that the end of life management of biodegradable
agricultural plastic products will be done at the farm to reduce the management of the waste and also its cost, only a few
of these norms are considered to be suitable for adaptation to cover also biodegradable agricultural plastic products. The
biodegradability validation criteria under composting conditions, such as the threshold percentage of biodegradation and disintegration,
the time and temperature, and the ecotoxicity, are presented for the main norms and standard testing methods. Based on these
different norms and their content, a list of specs and technical requirements that could be adapted to meet farm composting
conditions for agricultural compostable plastics is proposed. These requirements may be used as criteria for the establishment
of a new integrative norm for agricultural compostable plastics. 相似文献
898.
899.
Li-Ming Shao Zhong-He Ma Hua Zhang Dong-Qing Zhang Pin-Jing He 《Waste management (New York, N.Y.)》2010,30(7):1165-1170
Bio-drying can enhance the sortability and heating value of municipal solid waste (MSW), consequently improving energy recovery. Bio-drying followed by size sorting was adopted for MSW with high water content to improve its combustibility and reduce potential environmental pollution during the follow-up incineration. The effects of bio-drying and waste particle size on heating values, acid gas and heavy metal emission potential were investigated. The results show that, the water content of MSW decreased from 73.0% to 48.3% after bio-drying, whereas its lower heating value (LHV) increased by 157%. The heavy metal concentrations increased by around 60% due to the loss of dry materials mainly resulting from biodegradation of food residues. The bio-dried waste fractions with particle size higher than 45 mm were mainly composed of plastics and papers, and were preferable for the production of refuse derived fuel (RDF) in view of higher LHV as well as lower heavy metal concentration and emission. However, due to the higher chlorine content and HCl emission potential, attention should be paid to acid gas and dioxin pollution control. Although LHVs of the waste fractions with size <45 mm increased by around 2× after bio-drying, they were still below the quality standards for RDF and much higher heavy metal pollution potential was observed. Different incineration strategies could be adopted for different particle size fractions of MSW, regarding to their combustibility and pollution property. 相似文献
900.
1IntroductionAs a many-volcano-distributed country,China is covered with many volcanoes and lava rocks.A-mong the one-thousand-or-so volcanoes,Changbai Mountain Volcano,Wudalianchi Volcano,Tengchong Volcano and Ashikule Volcano of West Kunlun are the mostlatentcatastrophic erup-tive active volcanoes.In recent years,the activity of the earth' s crust in some volcanic areas isobviously becoming increasing violent.Butfew scholars have monitored and evaluated volcano inChina.So building VDI… 相似文献