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低温等离子体联合技术降解甲苯气体的研究 总被引:1,自引:0,他引:1
以自制的纳米钛酸钡基介电材料为催化剂,以电工陶瓷拉西环为载体,利用介质阻挡放电产生的低温等离子体对常压下流动态含甲苯的空气进行处理,研究了电场强度、空塔气速、甲苯初始浓度及不同填料情况下甲苯的降解及臭氧产生情况,初步探讨了等离子体联合技术降解甲苯的机制,并进行了产物分析.实验结果表明,甲苯降解率随电场强度的提高而上升,随空塔气速和甲苯初始浓度的增加而降低;随反应器内填料变化,甲苯降解率表现为催化剂填料》普通填料》无填料,其降解率最高可达95%.当电场强度》13.0 kV/cm时,臭氧浓度因受到过量的高能电子攻击而发生分解,表现为臭氧浓度随电场强度的继续增加而降低,故最佳电场强度为13.0 kV/cm.当9.0 kV/cm<电场强度<13.0 kV/cm,臭氧产量表现为催化剂填料>普通填料>无填料,纳米钛酸钡基介电材料大大增强了臭氧的产量. 相似文献
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白泥对填埋场垃圾降解的影响实验研究 总被引:1,自引:0,他引:1
在4个相同的密封聚乙烯塑料罐中,分别装填相同组分和重量的青岛市居民区的生活垃圾,并且在4个罐中按不同比例添加白泥,与垃圾混合均匀。实验模拟填埋场的环境条件。定期监测4个罐渗滤液的水质变化,分析比较白泥的添加及添加量的多少对渗滤液的衰减的影响。实验结果表明,白泥的添加能够向反应系统提供一定数量的碱度,可以防止反应系统因出现酸过度累积而受到抑制,在一定程度上加快了垃圾的降解进程。这不仅对于减轻渗滤液处理设施的负荷、加速填埋场的稳定化起着积极作用,而且可以为白泥的资源化利用提供一个可行的途径。 相似文献
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We investigated foliar and litter responses of European aspen (Populus tremula L.) to urbanization, including factors such as increased temperature, moisture stress and nitrogen (N) deposition. Leaf samples were collected in 2006-2008 from three urban and three rural forest stands in the Helsinki Metropolitan Area, southern Finland, and reciprocal litter transplantations were established between urban and rural sites. Urban leaves exhibited a higher amount of epicuticular waxes and N concentration, and a lower C:N ratio than rural ones, but there was no difference in specific leaf area. Urban litter had a slightly higher N concentration, lower concentrations of lignin and total phenolics, and was more palatable to a macrofaunal decomposer. Moreover, litter decay was faster at the urban site and for urban litter. Urbanization thus resulted in foliar acclimatization in terms of increased amount of epicuticular waxes, as well as in accelerated decomposition of the N-richer leaf litter. 相似文献
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近年来我国己成为世界第一煤炭生产国、消费国和进口国.2013年实施电煤价格并轨后,我国国内煤价与国际煤价的波动趋势也将日趋一致.在国内煤炭供给过剩的情况下,我国煤炭进口却仍在大幅增加,对我国煤炭市场造成了较大影响.因此,准确预测国际煤炭价格既有利于择机进口煤炭,也有助于进一步完善国家煤炭应急储备机制.通过整体经验模态分解(EEMD),非平稳煤价序列被分解重组为正常市场波动、重大事件影响、长期趋势等具有不同经济含义的时间序列.这三项时间序列被用于支持向量机(SVM)组合建模对国际煤价进行了一年内短期预测.研究发现:2013年国际煤炭价格将呈整体下跌趋势,趋向长期趋势线,并处于低位小幅波动. 相似文献
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Marrs RH Galtress K Tong C Cox ES Blackbird SJ Heyes TJ Pakeman RJ Le Duc MG 《Journal of environmental management》2007,85(4):1034-1047
Conservation management in Europe is often geared towards restoring semi-natural ecosystems, where the objective is to reverse succession and re-establish early-successional communities, to comply with national and international conservation targets. At the same time, it is increasingly recognised that ecosystems provide services that contribute to other, possibly conflicting policy requirements. Few attempts have been made to define these conflicts. Here, we assess some potential conflicts using a Calluna vulgaris-dominated moorland invaded by bracken (Pteridium aquilinum) as a model system, where the current policy is to reverse this process and restore moorland. We examined impacts of bracken control treatments on services (stocks and losses of C and mineral nutrients), litter turnover and biodiversity within a designed experiment over 7 years. Bracken litter was >2000 g m(-2) in untreated plots, and treatments reduced this quantity, and its element content, to varying degrees. Cutting twice per year was the most successful treatment in reducing bracken litter and its element content, increasing litter turnover, and increasing both mass and diversity of non-bracken vegetation. Diversity was greatest where bracken litter had been reduced, but species composition was also influenced by light sheep grazing. There was a significant loss of some chemical elements from bracken that could not be accounted for in other pools, and hence potentially lost from the system. In absolute terms large amounts of C and N were lost, but when expressed as a percentage of the total amount in the system, Mg was potentially more important with losses of almost a third of the Mg in the surface soil-vegetation system. There is, therefore, a potential dilemma between controlling a mid-successional invasive species for conservation policy objectives, especially when that species has evolved to sequester nutrients, and the negative effect of increasing environmental costs in terms of carbon accounting required, the potential input of nutrients to aquatic systems, and long-term nutrient loss. There is, therefore, a need to balance conservation goals against potential damage to biogeochemical structure and function. 相似文献
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Wood decomposition model for boreal forests 总被引:1,自引:0,他引:1
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Menghan Li Yao Zhang Jiancheng Yang Xiaori Liu Zhenguo Li Qiang Zhang 《环境科学学报(英文版)》2021,33(5):157-171
Selective catalytic reduction is the most efficient and reliable equipment for NOx control in current diesel engines. However, the issue of urea crystallization becomes increasingly serious with the implement of the new emissions standards. In this paper, urea deposit samples collected from engine test bed and tube furnace were characterized by thermogravimetric analysis and Fourier transform-infrared analysis to aid the comprehension of urea deposit formation. Moreover, thermogravimetric tests were conducted to disclose the effects of catalyst on the thermal decomposition processes of urea deposit. The results indicated that less temperature resistant species are formed in the engine test bed than in the tube furnace at conditions with the same temperatures. The main compositions in the World Harmonized Transient Cycle (WHTC) urea deposits are urea, cyanuric acid (CYA) and ammelide, implying that accelerating the decomposition of these species could prevent the accumulation of urea deposit. CuWTi, Cuβ and CuZSM catalysts could lead to increased yield of CYA during pure urea thermolysis. Cuβ, CuWTi and VWTi catalysts tend to promote the thermolysis of CYA while VWTi has the most significant catalytic effects on the thermal decomposition of ammelide and ammeline. 相似文献