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101.
以商业SCR催化剂为研究对象,探究SO_2氧化转化规律及其对SCR催化剂的影响,并用BET、NH_3-TPD、H_2-TPR、XRD、XPS、DRIFT等方法表征反应前后催化剂表面变化情况。研究表明:随着温度和O_2体积分数的增加,SO_2氧化转化效率升高;随着SO_2初始浓度和空速的增加,SO_2氧化转化效率降低。SO_2发生氧化后,商业催化剂的比表面积和平均孔径减小,催化剂晶体结构没有发生变化,催化剂表面酸性位点整体增加且其氧化还原活性略微降低。由于SO_2与催化剂相互作用,催化剂表面的元素价态发生一定的迁移,且产生了金属硫酸盐(OSO),消耗表面羟基。同时SO_2与V~(5+)反应使其转化为V~(4+)。可为进一步进行催化剂安全运行和维护提供参考。 相似文献
102.
103.
鸟粪石分析与表征技术综述 总被引:2,自引:0,他引:2
对X射线衍射(XRD)、傅里叶红外光谱(FT—IR)和拉曼光谱(Ralnan)、热分析(TGA)及化学分析法等技术用于分析和表征鸟粪石的最新研究进展进行了综述。表明X射线衍射、傅里叶红外光谱和拉曼光谱等能定性判断所得沉淀中是否含有鸟粪石,而难以定量分析鸟粪石含量。通过元素分析以及由此而建立的鸟粪石含量计算方法可以定量确定沉淀中鸟粪石的含量。热分析能提供热性能信息从而为所得沉淀的干燥处理过程提供有用的依据。 相似文献
104.
Landfill leachates with di erent ages (mature leachate, 11 years; semi-mature leachate, 5 years; fresh leachate, under operation)
were collected from Laogang Refuse Landfill, Shanghai to characterize the colloid size distribution and variations of leachate. These
leachates were separated using micro-filtration and ultra-filtration into specific size fractions, i.e., suspended particles (SP) (> 1.2 m),
coarse colloids (CC) (1.2–0.45 m), fine colloids (FC) (0.45 m, 5 kDa/1 kDa molecular weight (MW)), and dissolved organic matters
(DM, < 5 kDa/1 kDa MW). The specific colloids in each size fraction were quantified and characterized through chemical oxygen
demands (COD), total solid (TS), pH, NH4
+-N, total organic carbon (TOC) and fixed solid (FS). It was found that COD, NH4
+-N and
TS in leachate decreased significantly over ages, while pH increased. The dissolved fractions (< 5 kDa/1 kDa) dominated (over 50%)
in three leachates in terms of COD, and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter
increased as the disposal time extended, with the TOC/COD ratio 30%–7%. Dissolved fractions decreased from 82% to 40% in terms
of TOC as the disposal time extended, suggested that the organic matter remained in leachate would form into middle molecular weight
substances during the degradation process. 相似文献
105.
To provide basic toxicity data for formulating risk characterization benchmarks, the effects of lead on survival, locomotion, and sperm morphology were investigated in the Asian earthworm Pheretima guillelmi. The LC50 of P. guillelmi for 7 and 14 d were 4285±339 mg/kg and 3207±248 mg/kg, which shows P. guillelmi can tolerate a higher concentration of lead nitrate. The average weight of the surviving earthworms decreased at concentration of 2800 mg Pb/kg soil, and the locomotor ability of earthworms exposed ... 相似文献
106.
This is the first detailed characterization of the airborne bacterial profiles in indoor environments. Two restaurants were selected for this study. Fifteen genera of bacteria were isolated from each restaurant and identified by three different bacterial identification systems including MIDI, Biolog and Riboprinter®. The dominant bacteria of both restaurants were Gram-positive bacteria in which Micrococcus and Bacillus species were the most abundant. Most bacteria identified were representative species of skin and respiratory tract of human, and soil. Although the bacterial levels in these two restaurants were below the limit of the Hong Kong Indoor Air Quality Objective (HKIAQO) Level 1 standard (i.e., < 500 cfu/m3), the majority of these bacteria were opportunistic pathogens. These results suggested that the identity of airborne bacteria should also be included in the IAQ to ensure there is a safety guideline for the public. 相似文献
107.
Characterization of disinfection byproduct formation potential in 13 source
waters in China 总被引:3,自引:1,他引:2
Junzhi Zhang Jianwei Yu Wei An Juan Liu Yongjing Wang Youjun Chen Jia Tai Min Yang 《环境科学学报(英文版)》2011,23(2):183-188
The formation potential of four trihalomethanes (THMFP) and seven haloacetic acids (HAA7FP) in 13 source waters taken from
four major water basin areas in China was evaluated using the simulated distribution system (SDS) chlorination method. The specific
ultraviolet absorbance (SUVA254: the ratio of UV254 to dissolved organic carbon (DOC)), which ranged between 0.9 and 5.0 L/(mg m),
showed that the organic compounds in di erent source waters exhibited di erent reactivities with chlorine. The HAA7FP of source
waters ranged from 20 to 448 g/L and the THMFP ranged from 29 to 259 g/L. The HAA7FP concentrations were higher than the
THMFP concentrations in all but one of the samples. Therefore, the risks of haloacetic acids (HAAs) should be of concern in some
source waters. TCM (chloroform) and BDCM (bromodichloromethane) were the major THM constituents, while TCAA (trichloroacetic
acid) and DCAA (dichloroacetic acid) were the major HAA species. Br-THM (brominated THM species) were much higher than Br-
HAA (brominated HAA species), and the formation of Br-DBP (Br-THM and Br-HAA) should be of concern when the bromide
concentration is over 100 g/L. 相似文献
108.
分析饮用水水源地水体和底泥中腐殖酸,对研究饮用水水源地水质十分必要.由此,综述了水体和底泥中的腐殖质提取技术,以及腐殖酸各表征方法的研究进展.由于腐殖酸分子组成的不确定性,一些实验方法,如可见光吸收法、紫外吸收法、红外光谱法、扫描电镜分析、核磁共振法等已应用于实验研究中腐殖酸的表征.讨论分析上述表征方法在腐殖酸结构与性能研究中的应用,优化或寻求更为准确可靠的腐殖酸表征方法,将有助于对腐殖酸的深入研究. 相似文献
109.
本文针对近年来出现在一些变电站SF6电压、电流互感器的液体硅橡胶绝缘护套出现龟裂老化这一现象,对发生老化的硅橡胶材料进行了性能测试和试验,并利用红外光谱分析、XPS分析、热失重等手段分析了其微观结构和物质组成的变化。研究发现老化后的液体硅橡胶中Si-C、Si-O官能团和Si、C、O元素的相对含量发生了变化,且随着老化程度的增加呈现出较为明显的规律,老化越严重,Si-C键含量越少,C元素的含量越少,O元素含量越多。本文认为,用官能团含量、元素相对含量可以准确地表征液体硅橡胶材料的老化程度。通过对不同老化程度的液体硅橡胶进行的憎水性、耐漏电起痕性能的试验也证实了本文的观点。 相似文献
110.
兽药和饲料添加剂在养殖业的大量使用,使其成为造成生态环境污染和人体健康损害的一个重要因素.发达国家已经开始采用生态风险评估技术对兽药进行有效的环境管理,而我国在兽药的环境风险管理方面依然处于盲区.喹乙醇是我国畜禽和水产养殖中应用最广泛的一种兽药添加剂.采用欧盟经典的兽药生态风险评估模型与方法,对其进行生态风险评估.结果显示,喹乙醇在土壤、地表水、地下水中的预测暴露浓度分别为0.313~2.68 mg·kg-1、0.928~10.2mg· L-1和0.281 ~3.10 mg·L-1,预测无效应浓度分别为>200 mg·kg-1、0.5 mg·L-1和0.5 mg·L-1,预测生态风险分别为< 1.34×10-2、1.856~20.4和0.562 ~ 6.20.可见,对于喹乙醇的风险管理要将重点放在降低其水生生态风险上.因此,兽药的生态风险评估技术可以为兽药的环境管理提供有效的技术支持. 相似文献