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951.
通过尿素法制备了一系列Ce掺杂改性的Ni-Al-Ox复合氧化物催化剂,并研究了催化剂的CO-NO反应性能.活性测试结果表明,Ni-Al-Ce-Ox的催化活性明显优于Ni-Al-Ox,且活性随着Ce含量的增加而提高.当Ce的掺杂量为20%时,250℃条件下,NO转化率高达95%以上,同时催化剂具有良好的抗H2O性能.XRD和Raman分析表明,Ce掺杂Ni-Al-Ox催化剂促进了氧空位产生.而XPS结果显示,氧空位随着Ce含量的增加而增加.H2-TPR结果表明,Ce的掺杂使催化剂的氧化还原性能增强.结合NO-TPD和FTIR的表征结果,进一步发现Ce的加入使表面氧难以将NO氧化成硝酸盐,有利于NO在Ce的氧空位上分解为N2或N2O,促进CO-NO反应的进行. 相似文献
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Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes 总被引:1,自引:0,他引:1
Iron oxide(FeO)coated by natural organic matter(NOM)is ubiquitous.The associations of minerals with organic matter(OM)significantly changes their surface properties and reactivity,and thus affect the environmental fate of pollutants,including nutrients(e.g.,phosphorus(P)).In this study,ferrihydrite/goethite-humic acid(FH/GE–HA)complexes were prepared and their adsorption characteristics on P at various p H and ionic strength were investigated.The results indicated that the Fe O–OM complexes showed a decreased P adsorption capacity in comparison with bare Fe O.The maximum adsorption capacity(Q_(max))decreased in the order of FH(22.17 mg/g)FH-HA(5.43 mg/g)GE(4.67 mg/g)GE-HA(3.27 mg/g).After coating with HA,the amorphous FH–HA complex still showed higher P adsorption than the crystalline GE–HA complex.The decreased P adsorption observed might be attributed to changes of the Fe O surface charges caused by OM association.The dependence of P adsorption on the specific surface area of adsorbents suggests that the Fe O component in the complexes is still the main contributor for the adsorption surfaces.The P adsorptions on Fe O–HA complexes decreased with increasing initial p H or decreasing initial ionic strength.A strong dependence of P adsorption on ionic strength and p H may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the Fe O component and P.Therefore,previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils,especially in humic-rich areas. 相似文献
954.
Pengjun Xu Bu Tao Zhiqiang Ye Hu Zhao Yue Ren Ting Zhang Yeru Huang Jiping Chen 《环境科学学报(英文版)》2016,28(10):102-111
The concentrations of 16 priority polycyclic aromatic hydrocarbons(PAHs) were measured in 23 farmland soil samples and 10 riverine sediment samples from Guiyu, China, and the carcinogenic risks associated with PAHs in the samples were evaluated. Guiyu is the largest electronic waste(EW) dismantling area globally, and has been well known for the primitive and crude manner in which EWs are disposed, such as by open burning and roasting. The total PAH concentrations were 56–567 ng/g in the soils and 181–3034 ng/g in the sediments.The Shanglian and Huamei districts were found to be more contaminated with PAHs than the north of Guiyu. The soils were relatively weakly contaminated but the sediments were more contaminated, and sediments in some river sections might cause carcinogenic risks to the groundwater system. The PAHs in the soils were derived from combustion sources,but the PAHs in the sediments were derived from both combustion and petroleum sources. 相似文献
955.
Chemical characteristics of fine particles and their impact on visibility impairment in Shanghai based on a 1-year period observation 总被引:1,自引:0,他引:1
Min Zhou Liping Qiao Shuhui Zhu Li Li Shengrong Lou Hongli Wang Qian Wang Shikang Tao Cheng Huang Changhong Chen 《环境科学学报(英文版)》2016,28(10):151-160
In this work, a one-year observation focusing on high time resolution characteristics of components in fine particles was conducted at an urban site in Shanghai. Contributions of different components on visibility impairment were also studied. Our research indicates that the major components of PM2.5 in Shanghai are water-soluble inorganic ions and carbonaceous aerosol, accounting for about 60% and 30% respectively. Higher concentrations of sulfate (SO42−) and organic carbon (OC) in PM2.5 occurred in fall and summer, while higher concentrations of nitrate (NO3−) were observed in winter and spring. The mass concentrations of Cl− and K+ were higher in winter. Moreover, NO3− increased significantly during PM2.5 pollution episodes. The high values observed for the sulfate oxidizing rate (SOR), nitrate oxidizing rate (NOR) and secondary organic carbon (SOC) in OC indicate that photochemical reactions were quite active in Shanghai. The IMPROVE (Interagency Monitoring of Protected Visual Environments) formula was used in this study to investigate the contributions of individual PM2.5 chemical components to the light extinction efficient in Shanghai. Both NH4NO3 and (NH4)2SO4 had close relationships with visibility impairment in Shanghai. Our results show that the reduction of anthropogenic SO2, NOx and NH3 would have a significant effect on the improvement of air quality and visibility in Shanghai. 相似文献
956.
957.
石油开采在规模不断扩张的同时,也造成了大面积的采区环境污染,严重降低了生态环境质量.为探索石油开采区域生态环境质量综合评价的有效方法,通过对石油开采区域生态环境质量及综合评价现状的分析,精选指标构建了石油开采区域生态环境质量的综合评价指标体系,利用专家调查法确定了各评价指标的相对权值,并构建了石油开采区域生态环境质量模糊综合评价模型,选择胜利油田某采区进行了综合评价的应用研究,对模糊综合评价模型的有效性进行了验证. 相似文献
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960.
基于高原环境的保障装备适应性技术研究 总被引:1,自引:1,他引:0
目的寻找和发现现役保障装备在高原保障过程中存在的问题,评估装备的高原工作性能,全面提升保障装备高原环境适应能力。方法依据高原环境特点,全面、准确定量掌握现役保障保障装备在高原环境下的实际性能,找出存在的突出问题,并在此基础上有针对性地开展高原环境保障装备适应性技术研究。结果从技术措施、调试工艺、各分系统间的匹配这三个方面提出提高保障装备高原环境适应性技术。结论通过适应性技术高原型保障装备可达到功能完备、性能可靠、适应高原环境现役主战装备的保障需求。 相似文献