Role of hydrogen bond capacity of solvents in reactions of amines with CO2: A computational study

Various computational methods were employed to investigate the zwitterion formation,a critical step for the reaction of monoethanolamine with CO_2,in five solvents(water,monoethanolamine,propylamine,methanol and chloroform) to probe the effect of hydrogen bond capacity of solvents on the reaction of amine with CO_2 occurring in the amine-based CO_2 capture process.The results indicate that the zwitterion can be formed in all considered solvents except chloroform.For two pairs of solvents(methanol and monoethanolamine,propylamine and chloroform) with similar dielectric constant but different hydrogen bond capacity,the solvents with higher hydrogen bond capacity(monoethanolamine and propylamine) facilitate the zwitterion formation.More importantly,kinetics parameters such as activation free energy for the zwitterion formation are more relevant to the hydrogen bond capacity than to dielectric constant of the considered solvents,clarifying the hydrogen bond capacity could be more important than dielectric constant in determining the kinetics of monoethanolamine with CO_2.     

Characteristics of atmospheric volatile organic compounds in urban area of Beijing: Variations, photochemical reactivity and source apportionment

Atmospheric volatile organic compounds (VOCs) were observed by an on-line gas chromatography-flame ionization detector monitoring system from November 2016 to August 2017 in Beijing. The average concentrations were winter (40.27 ± 25.25 μg/m³) > autumn (34.25 ± 19.90 µg/m³) > summer (32.53 ± 17.39 µg/m³) > spring (24.72 ± 17.22 µg/m³). Although benzene (15.70%), propane (11.02%), ethane (9.32%) and n-butane (6.77%) were the most abundant species, ethylene (14.07%) and propene (11.20%) were the key reactive species to ozone formation potential (OFP), and benzene, toluene, ethylbenzene, m-xylene + p-xylene and o-xylene (54.13%) were the most reactive species to secondary organic aerosol formation potential (SOAFP). The diurnal and seasonal variations indicated that diesel vehicle emission during early morning, gasoline vehicle emission at the traffic rush hours and coal burning during the heating period might be important sources. Five major sources were further identified by positive matrix factorization (PMF). The vehicle exhaust (gasoline exhaust and diesel exhaust) was found to be contributed most to atmospheric VOCs, with 43.59%, 41.91%, 50.45% and 43.91%, respectively in spring, summer, autumn and winter; while solvent usage contributed least, with 11.10%, 7.13%, 14.00% and 19.87%, respectively. Biogenic emission sources (13.11%) were only identified in summer. However, both vehicle exhaust and solvent usage were identified to be the key sources considering contributions to the OFP and SOAFP. Besides, the contributions of combustion during heating period and gasoline evaporation source during warm seasons to OFP and SOAFP should not be overlooked.     

基于平面波导传感器的恩诺沙星与诺氟沙星同时检测方法

为了实现对于环境中抗生素恩诺沙星与诺氟沙星的同时快速灵敏检测,本研究基于间接竞争免疫反应模式及荧光全内反射原理,以本课题组自主研发的平面波导生物传感器为平台,建立了恩诺沙星和诺氟沙星的同时快速检测方法.通过对抗体浓度、pH及钙离子浓度的优化,提高了检测方法的灵敏度,结果表明,恩诺沙星的检测限为0.34μg·L~(-1),诺氟沙星的检测限为0.14μg·L~(-1).在单物质检测的基础上,首次实现了基于平面波导传感器的两种抗生素同时检测,检测周期仅15 min,检测限为0.06μg·L~(-1).本研究从理论上分析了同时检测时检测限下降、灵敏度提高的原因,为利用生物传感器法同时检测抗生素提供了理论指导及技术支撑.     

高温烟气静电除尘中试试验研究

为了研究在宽间距静电除尘器内部流动的大流量高温烟气中颗粒物的静电捕集特性,基于CFB锅炉中试试验平台设计并搭建了高温静电除尘中试装置.试验了板间距300mm、最高温度达到1020K的实际烟气中颗粒物的静电捕集特性,获得了放电电压、温度和烟气流速等关键因素对颗粒物的静电捕集的影响规律.实验结果表明,高温静电除尘器中烟气流速为0.3m/s,温度为1020K下达到了82.2%的除尘效率,证实了针对实际高温烟气,静电除尘器有较好的颗粒捕集效果.通过对比563K到1020K下的热态试验以及常温下的冷态试验,发现颗粒捕集效率随温度的上升迅速降低,这与高温下流速的上升、放电电压的降低以及气体黏性的增加有关.     

Effects of 1-octyl-3-methylimidazolium nitrate on the microbes in brown soil

The toxicity of ionic liquids(ILs) on soil organisms has aroused wide attention due to their high-solubility. The present investigation focused on the toxicity of 1-octyl-3-methylimidazolium nitrate([C_8mim]NO_3) on the microbial populations(bacteria, fungi, and actinomycetes), soil enzyme(urease, dehydrogenase, acid phosphatase, and β-glucosidase)activities, microbial community diversity using terminal restriction fragment length polymorphism(T-RFLP), and abundance of the ammonia monooxygenase(amoA) genes of ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB) using quantitative real-time polymerase chain reaction(q-PCR) in brown soil at each trial with doses of 0, 1.0, 5.0,and 10.0 mg/kg on days 10, 20, 30, and 40. The contents of [C_8mim]NO_3 in soil were measured using high performance liquid chromatography with recoveries of 84.3% to 85.2%, and changed less than 10% during the experimental period. A significant decrease was observed from the bacteria, fungi and actinomycetes populations at 10.0 mg/kg, at which the urease activity was inhibited and the β-glucosidase activity was stimulated on days 20, 30, and 40. In addition, [C_8mim]NO_3 inhibited the dehydrogenase activity at 10 mg/kg on days 30 and 40 and the acid phosphatase activity on day 20. The diversity of the soil microbial community and the gene abundance of AOA-and AOB-amo A were also inhibited. Furthermore, the present investigation provided more scientific information for the toxicity evaluation of ILs in soil.     

Atmospheric isoprene and monoterpenes in a typical urban area of Beijing: Pollution characterization, chemical reactivity and source identification

Continuous observation of isoprene, α-pinene and β-pinene was carried out in a typical urban area of Beijing from March 2014 to February 2015, using an AirmoV OC online analyzer. Based on the analysis of the ambient level and variation characteristics of isoprene, α-pinene and β-pinene, the chemical reactivity was studied, and their sources were identified. Results showed that the concentrations of isoprene, α-pinene and β-pinene in the urban area of Beijing were lower than those in richly vegetated areas; the concentrations of isoprene were at a moderate level compared with those of previous studies of Beijing. Concentrations of isoprene, α-pinene and β-pinene showed different seasonal, monthly, daily and diurnal variations, and all of the three species showed higher level at night than those in the daytime as a whole, the variations of isoprene, α-pinene and β-pinene mainly influenced by emission of sources, photochemical reaction, and meteorological parameters. Isoprene was the largest contributor to the total OFP values than α-pinene and β-pinene. α-Pinene was the largest contributor to the total SOAFP values than isoprene and β-pinene in autumn, while isoprene was the largest one in other seasons. Isoprene, α-pinene and β-pinene were derived mainly from biological sources; and α-pinene level were also affected by industrial sources. To reduce the concentrations of isoprene, α-pinene and β-pinene, it is necessary to scientifically select urban green plant species, and more strict control measures should be taken to reduce the emission of α-pinene from industrial sources, such as artificial flavors and resins synthesis processes.     

Pollution characteristics of atmospheric dustfall and heavy metals in a typical inland heavy industry city in China

Through field sampling of atmospheric dustfall in regions of Zhuzhou City, China for a period of one year, the deposition fluxes of atmospheric dustfall and five heavy metals contained inside, including Cr, As, Cd, Hg and Pb, were analyzed. Meanwhile the enrichment factor and index methods were used to analyze the pollution characteristics of heavy metals of atmospheric dustfall in Zhuzhou. The annual deposition flux of atmospheric dustfall in Zhuzhou was 50.79 g/(m~2·year), while the annual deposition fluxes of Cr, As, Cd, Hg and Pb were 9.80, 59.69, 140.09, 0.87 and 1074.91 mg/(m~2·year), respectively.The pollution level of atmospheric dustfall in Zhuzhou was relatively lower compared with most other cities in China, but the deposition fluxes of As, Cd, Hg and Pb in atmospheric dustfall in Zhuzhou were much higher than that in most cities and regions around the world. Cd is the typical heavy metal element in atmospheric dustfall in Zhuzhou, and both the enrichment factor and pollution index of Cd were the highest. Cd, Hg, Pb and As in atmospheric dustfall were mainly from human activities. According to the single-factor index, Nemerow index and pollution load index analyses, the atmospheric dustfall in Zhuzhou could easily cause severe heavy metal pollution to urban soil, and the most polluting element was Cd, followed by Pb, As and Hg. Only the pollution level of Cr lay in the safety region and mainly originated from natural sources.     

京津冀地区黄标车政策的总量减排效益评估

为评估黄标车提前淘汰补贴和禁行政策的实施效果,并对这两种政策进行比较,在梳理京津冀地区相关政策措施的基础上,采用排放因子法评估其总量减排效益.结果表明:(1)京津冀地区黄标车淘汰政策有较好的减排效益,政策实施以来CO、HC、NO_x、PM_(2.5)、PM_(10)累计减排量分别为500.32、39.79、31.82、0.96、1.06万t.(2)黄标车政策减排效益最突出的污染物为CO、HC、NO_x,为大气污染总量减排作出较大贡献.(3)小型载客与轻型载货汽油车是CO与HC的减排主体,重型载货柴油车是NO_x和颗粒物的主要减排贡献车型.(4)京津冀13个城市,道路密集的城区减排更明显.北京市、天津市、石家庄市CO、HC减排较其他城市更显著,天津市、石家庄市、唐山市、邯郸市NO_x和颗粒物减排更显著.(5)提前淘汰补贴和禁行两个政策相比,前者减排效益具有时间延续性,在政策实施后几年效益仍较明显;后者在政策实施前期减排效益明显,随时间而衰减.各地在制定黄标车与老旧机动车政策时,建议前期加强禁行政策、后期加强淘汰补贴政策执行力度.     

佛山市典型铝型材行业表面涂装VOCs排放组成

选取佛山市典型铝型材行业不同表面涂装工艺(溶剂型涂料涂装、水性涂料涂装、电泳涂装、粉末喷涂)有组织废气VOCs进行了采样分析.结果表明,溶剂型涂料涂装废气VOCs浓度(63. 90~149. 67 mg·m~(-3))要远大于其他3种涂装工艺(2. 99~21. 93 mg·m~(-3)). VOCs组成来看,溶剂型涂料涂装废气VOCs以芳香烃为主,比例在52. 32%~71. 55%之间,主要污染物包括甲苯、乙苯、二甲苯等苯系物和乙酸乙酯等含氧挥发性有机物(OVOCs).水性涂料涂装废气以OVOCs为主,如乙酸乙酯(48. 59%)、四氢呋喃(8. 43%),芳香烃比例(11. 32%)远低于溶剂型涂料涂装废气.异丙醇是电泳涂装废气中最主要的VOCs化合物,贡献比例高达81. 19%.而粉末涂料涂装废气VOCs污染物主要是丙酮(30. 25%),以及丙烷(15. 48%)、乙烯(12. 15%)、乙烷(9. 35%)、正丁烷(5. 16%)等C2~C4的烷烃和烯烃.臭氧生成潜势(OFP)计算结果表明,溶剂型涂料涂装废气排放单位质量VOCs的臭氧生成潜势(OFP,以O3/VOCs计,下同)最高(3. 89 g·g~(-1)),其次是粉末喷涂(2. 53 g·g~(-1)),而水性涂料涂装和电泳涂装则较低(1. 31 g·g~(-1)和0. 85 g·g~(-1)).溶剂型涂料涂装废气中芳香烃对OFP贡献比例高达93. 28%,有9种C7~C10芳香烃位列OFP排名前10化合物;水性涂料涂装废气中乙酸乙酯、间/对-二甲苯和甲苯的臭氧生成潜势占比最高,分别为23. 24%、21. 76%和17. 07%;粉末涂料涂装废气中的关键活性组分则为乙烯、丙烯和1-丁烯等低碳烯烃,烯烃对其OFP贡献为71. 11%;电泳涂料涂装废气中异丙醇的OFP贡献(65. 08%)明显高于其他组分(6%).     

秋冬季厦门岛大气颗粒物中PCBs的污染特征及入海通量

于2006至2008年秋季和冬季在台湾海峡西岸厦门岛采集大气颗粒物样品,分析28种多氯联苯（PCBs）,包括指示性PCBs和类二恶英PCBs的含量特征及组成,探讨其可能来源,并对其干沉降入海通量进行估算。结果显示,2006至2008年秋冬季厦门岛大气颗粒物中PCBs的浓度分别为0.43~53.55、2.07~81.14和3.79~153.39 pg/m³,主要以高氯取代PCBs为主,类二恶英PCBs毒性当量值与主要城市相当。冬季PCBs浓度高于秋季,且2006至2008年的秋冬季PCBs浓度呈上升趋势,这可能受到厦门市汽车尾气和工业废气排放等人类活动导致大气颗粒物含量升高的影响。气团后向轨迹分析表明,冬季厦门岛大气颗粒物中较高浓度的PCBs主要受中国北方大陆污染气团来源的影响,而秋季大多来源于洁净海洋气团。秋季和冬季,大气颗粒物中PCBs的沉降通量分别为3.79和8.32 ng/（m²·d）,按调查区域覆盖面积（63 000 km²）估算,通过大气干沉降向台湾海峡输入的PCBs量分别为22 kg和47 kg。