粉末活性炭对水溶液中邻苯二甲酸二(2-乙基己基)酯的吸附

采用静态吸附法研究了邻苯二甲酸二(2-乙基己基)酯(DEHP)在粉末活性炭上的吸附性能,探讨了粉末活性炭对DEHP的吸附等温线、吸附动力学和吸附热力学特征。结果表明,粉末活性炭对DEHP吸附等温线符合Langmuir吸附等温式;分别采用拟一级反应、拟二级反应和颗粒内扩散反应模型对吸附动力学过程进行了拟合,实验数据遵循颗粒内扩散模型;在20、30、40和50℃下,对应的吉布斯自由能(ΔG0)分別为-2.014、-1.441、-0.868和-0.296 kJ/mol,表明该反应自发进行;焓变(ΔH0)<0,证实该反应为放热反应;熵变(ΔS0)<0,说明该吸附反应是熵值减小的过程;吸附活化能Ea=7.234 kJ/mol和粘附概率S*=0.036分别介于5～40 kJ/mol和0～1范围内,表明该吸附过程主要为物理吸附;活性炭吸附前后红外谱图分析,也验证物理吸附为PAC吸附DEHP之主要机制。     

Evaluation of Human Exposure to Ambient PM10 in the Metropolitan Area of Mexico City Using a GIS-Based Methodology

ABSTRACT

The main goal of this study was to evaluate the magnitude of outdoor exposure to fine particulate matter (PM₁₀) potentially experienced by the population of metropolitan Mexico City. With the use of a geographic information system (GIS), spatially resolved PM₁₀ distributions were generated and linked to the local population. The PM₁₀ concentration exceeded the 24-hr air quality standard of 150 μg/m³ on 16% of the days, and the annual air quality standard of 50 μg/m³ was exceeded by almost twice its value in some places. The basic methodology described in this paper integrates spatial demographic and air quality databases, allowing the evaluation of various air pollution reduction scenarios. Achieving the annual air quality standard would represent a reduction in the annual arithmetic average concentration of 14 μg/m³ for the typical inhabitant. Human exposure to particulate matter (PM) has been associated with mortality and morbidity in Mexico City; reducing the concentration levels of this pollutant would represent a reduction in mortality and morbidity and the associated cost of such impacts. This methodology is critical to assessing the potential benefits of the current initiative to improve air quality implemented by the Environmental Metropolitan Commission of Mexico City.     

铁碳微电解-Fenton法预处理苯胺基乙腈生产废水

采用铁碳微电解-Fenton法对苯胺基乙腈生产废水进行预处理实验。通过静态实验确定铁碳微电解最佳条件为铁屑投加量300 g/L,Fe/C质量比为2∶3,反应75 min,不需要调节进水pH;Fenton反应最佳条件为铁碳微电解出水pH=4,30%H2O2投加量15 mL/L,在搅拌条件下反应60 min;然后沉淀反应时调节pH为9,混凝沉淀75 min。在上述条件下通过动态实验得到系统连续反应在48 h内废水的COD和苯胺去除率在50%和70%以上,可生化性BOD5/COD也保持在0.3以上,为后续生物处理创造了良好条件。     

高浓度悬浮液的混凝实验及机理研究

进行了高浓度悬浮液的混凝实验研究。为研究混合阶段渐变剪切速率对混凝沉降效果的影响,在混合阶段分别采用固定搅拌转速和渐变搅拌转速进行实验。在混合阶段采用固定搅拌转速,当搅拌转速为210r/min时,絮体二维分形维数最高为1.8847,悬浮液浊度最低为118NTU。采用渐变搅拌转速的方法,由210r/min开始逐渐降低搅拌转速,絮体二维分形维数最大,为1.9205,处理后悬浮液浊度最小,为107NTU。在一般混凝沉降过程的规律及模型的基础上,提出了高浓度悬浮液混凝沉降过程的物理模型。     

膜生物反应器污水处理数学模型研究及其应用现状

膜生物反应器(MBR)具有与传统工艺无法比拟的优势而成为污水处理中很有前景的工艺。由于MBR工艺本身固有的复杂性和不确定性,发展一种能够为该工艺提供整体性理解的模型是相当必要的。模型的建立可为MBR污水处理的优化设计和运行控制提供理论依据。给出了3类用于模拟MBR工艺的模型:生物动力学模型、膜污染模型和对MBR完整描述的综合模型。在此基础上,阐述了每个模型各自的机制和功能,分析讨论了模型研究与应用中存在的问题,并提出了MBR相关模型的发展前景。     

Seasonal and spatial variation of organic tracers for biomass burning in PM1 aerosols from highly insolated urban areas

PM₁ aerosol characterization on organic tracers for biomass burning (levoglucosan and its isomers and dehydroabietic acid) was conducted within the AERTRANS project. PM₁ filters (N?=?90) were sampled from 2010 to 2012 in busy streets in the urban centre of Madrid and Barcelona (Spain) at ground-level and at roof sites. In both urban areas, biomass burning was not expected to be an important local emission source, but regional emissions from wildfires, residential heating or biomass removal may influence the air quality in the cities. Although both areas are under influence of high solar radiation, Madrid is situated in the centre of the Iberian Peninsula, while Barcelona is located at the Mediterranean Coast and under influence of marine atmospheres. Two extraction methods were applied, i.e. Soxhlet and ASE, which showed equivalent results after GC-MS analyses. The ambient air concentrations of the organic tracers for biomass burning increased by an order of magnitude at both sites during winter compared to summer. An exception was observed during a PM event in summer 2012, when the atmosphere in Barcelona was directly affected by regional wildfire smoke and levels were four times higher as those observed in winter. Overall, there was little variation between the street and roof sites in both cities, suggesting that regional biomass burning sources influence the urban areas after atmospheric transport. Despite the different atmospheric characteristics in terms of air relative humidity, Madrid and Barcelona exhibit very similar composition and concentrations of biomass burning organic tracers. Nevertheless, levoglucosan and its isomers seem to be more suitable for source apportionment purposes than dehydroabietic acid. In both urban areas, biomass burning contributions to PM were generally low (2 %) in summer, except on the day when wildfire smoke arrive to the urban area. In the colder periods the contribution increase to around 30 %, indicating that regional biomass burning has a substantial influence on the urban air quality.     

Field evaluation of nitrogen availability from fresh and composted manure

Prediction of manure nitrogen availability to crops is key to ensuring adequate production while minimizing potential adverse environmental impacts. This field study estimated first-year and residual N availability from several manures subjected to various levels of processing, and evaluated the applicability of the pre-sidedress soil N test (PSNT) in fields receiving the different manures using corn (Zea mays L.) as the test crop. Plots received several rates of fresh (FP), dried (DP), or composted (CP) poultry (Gallus gallus domesticus) manure, composted cow (Bos taurus) (CC) manure, ammonium nitrate (AN), or no N. Crop yields and N uptake from plots where CC was applied were undistinguishable from controls in most years, whereas poultry manures significantly increased corn production. Average apparent first-year N availability, as measured by fertilizer equivalence, was 57, 53, 14, and 4% for FP, DP, CP, and CC respectively. Apparent second-year N availability, as measured by relative effectiveness, was 18, 19, 12, and 7% for FP, DP, CP, and CC; however, for CC both first- and second-year estimates of apparent N recovery (ANR) could statistically not be separated from the controls. Apparent nitrogen avail-ability was greater for less processed manures and for CP compared to CC, emphasizing that producers should know the source and level of compost stability when these materials are used as a primary nutrient source. The PSNT successfully (87% correct) identified sites with a critical value of 24 mg kg(-1) that were N sufficient across a variety of N amendments from those that would have benefitted from additional N input.     

球团竖炉工艺除尘用新型高效电除尘器

根据竖炉烟尘特点,提出电除尘器设计方面值得推广应用的新技术,如振打方式、振打锤形式、绝缘悬吊方式、供电方式等,力求实用。     

Simultaneous monitoring of PCB profiles in the urban air of Dalian, China with active and passive samplings

The concentration of polychlorinated biphenyls (PCBs) in the urban air of Dalian, China was monitored from November 2009 to October 2010 with active high-volume sampler and semipermeable membrane device (SPMD) passive sampler. The concentration of PCBs (particle + gas) ( ∑ PCBs) ranged from 18.6 to 91.0 pg/m 3 , with an average of 50.9 pg/m 3 , and the most abundant dioxin-like PCB (DL-PCBs) was PCB118. The WHO-TEQ values of DL-PCBs were 3.6-22.1 fg/m3 , with an average of 8.5 fg/m 3 , and PCB126 was the maximum contributor to ∑ TEQ. There was a much larger amount of PCBs in the gas phase than in the particulate phase. The dominant PCB components were lower and middle molecular weight PCBs. With increasing chlorination level, the concentration of the PCB congeners in the air decreased. The gas-particulate partitioning of PCBs was different for the four seasons. The gas- particulate partitioning coefficients (logK p ) vs. subcooled liquid vapor pressures (logP L 0 ) of PCBs had reasonable correlations for different sampling sites and seasons. The absorption mechanism contributed more to the gas-particulate partitioning process than adsorption. Correlation analysis of meteorological parameters with the concentration of PCBs was conducted using SPSS packages. The ambient temperature and atmospheric pressure were important factors influencing the concentration of PCBs in the air. The distribution pattern of the congeners of PCBs and the dominant contributors to DL-PCBs and TEQ in active samples and SPMDs passive samples were similar. SPMD mainly sequestrated gas phase PCBs.     

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the RO_x (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%–150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%–50% enhancements in the areas around 35–40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.