A second generation model for regional-scale transport/chemistry/deposition

The regional-scale transport, chemistry and deposition of acidifying compounds, photochemical oxidants, and their precursors are analyzed using a second-generation Eulerian model. The important atmospheric processes are incorporated using chemical, dynamical and thermodynamical parameterizations having sufficient detail to accommodate boundary layer-free troposphere exchange in cloudy and cloud-free environments, and in-cloud and below-cloud wet removal and chemistry. Forty-one species are considered, many of which are also present in the liquid-drop phases. In the regional scale transport, the advected species are NO, NO₂, SO₂, SO⁻²₄, O₃, HNO₃, NH₃, PAN, H₂O₂, HCHO, alkanes, C₂H₄, other olefins, aromatics, RCHO, ROOH, HNO₂, RONO₂ and RO₂NO₂. The model capabilities are illustrated by showing simulations in which non-precipitating clouds are present to absorb gas-phase species, chemically alter these, and then release them to the atmosphere.     

新型MnOx/CNTs催化剂低温选择性催化还原NO

采用等体积浸渍法制备了MnOx/CNTs催化剂,用于低温NH3选择性催化还原(SCR)NO的实验.使用BET,FT-IR,TEM和XRD对催化剂进行表征,结果表明:碳纳米管经混酸超声分散,增加了羧基活性基团,锰氧化物颗粒分布较均匀.在模拟烟气条件下,考察了催化剂的MnOx负载量、煅烧温度及质量和烟气流速比(W/F)对NO脱除率的影响.煅烧温度为773 K,MnOx负载量为10%时,NO脱除率达到98.56%;W/F为2～3 mg/(mL·min-1)时NO的脱除率更高.     

CeOx/AC催化剂NH3选择性催化还原NO

以用不同浓度的HNO3预处理后的椰壳活性炭为载体,负载铈制备SCR催化剂。利用比表面积分析仪(BET)、X射线衍射(XRD)、扫描电镜(SEM)和催化剂活性实验,探讨了不同变量如金属离子的分布、焙烧温度和载体属性对催化活性的影响。结果表明,HNO3处理后,经500℃焙烧金属铈负载量为7%的催化剂表现出优良的催化性能。在90℃时,NO转化率在90%以上,随温度升高,达到接近100%的NO转化率。     

膜气体吸收技术分离VOCs/N2混合气性能的研究

以C₆H₆/N₂混合气为代表,疏水性聚丙烯中空纤维膜为气液接触膜,n-甲酰吗啉(NFM,n-formyl morpholine)水溶液为吸收剂,研究了膜气体吸收法分离VOCs/N₂混合气性能。考察了吸收剂流量、吸收剂体积分数、进口气流量、进口气浓度和膜组件结构等诸因素对分离性能的影响。结果表明,在吸收剂流量为20～100 mL/min,进口气流量为40～300 mL/min,进口气浓度为10.2 mg/L的条件下,苯的去除率为65.0 % ～ 99.6 %,总体积传质系数为0.0157～0.08412 s^-1。实验证明,采用疏水性多孔膜气体吸收法,NFM水溶液吸收分离VOCs/N₂混合气具有较高的分离效率和较快的传质速率。     

ACF脱除SO2/NOx反应器数学模型的建立

在大量试验研究获得数据基础上,结合机理分析,考虑ACF同时脱除多种污染物的主要影响因素,运用气固催化反应动力学方法进行分析,采用"混合模型法"建立ACF反应器数学模型,并用MATLAB软件与实验数据相结合迭代求取了模型参数,求出了宏观反应速率方程,并将计算模拟值与实验值进行比对,发现模拟结果与实验结果基本吻合,证实了模型的可靠性.为ACF反应器从试验研究的成果放大到工业规模的应用奠定了基础.     

CS/PEG/PFT膜制备及对含铜废水的处理

实验将溶胶凝胶法和高分子辅助倒相法结合,制备出一种新型的壳聚糖/聚乙二醇/亚铁氰化钾钛(CS/PEG/PFT)复合膜,通过FT-IR和SEM对膜进行表征后,将其用于模拟铜废水的吸附和脱附实验,并探究出膜吸附的最佳工艺条件为:p H 5.50、实验温度55℃、实验时间2 h,该条件下,膜对铜离子最大吸附量为9.85 mg/g,去除率达到95%以上。CS/PEG/PFT膜的除铜过程符合Langmuir等温吸附方程(y=0.0597x+0.0168),线性相关度达到0.9917。     

Bio-based films/nanopapers from lignocellulosic wastes for production of added-value micro-/nanomaterials

Environmental Science and Pollution Research - The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received...     

Adsorption/thermal desorption-GC/MS for the analysis of pesticides in the atmosphere

An analytical methodology using Automatic Thermal Desorption (ATD) and GC/MS was developed for the determination of the pesticides alachlor, atrazine, captan, formothion, lindane and phosalone in atmospheric samples. This methodology was developed to evaluate the atmospheric contamination by pesticides during treatments and by post-application. Atmospheric samples were collected by using (4 i.d. x 89 mm) stainless steel sampling tubes containing 125 mg of adsorbents at a flow rate of 80 ml min-1. Different types of adsorbents were tested for their ability to efficiently trap pesticides under study: Tenax TA, Carbopack Y, Carbopack B, Carbotrap, Carboxen, Chromosorb 106 and XAD-4. Results of experiment show that Tenax gives the better results for all the pesticides used but the use of the thermal-desorption method, especially for pesticides with low volatility and/or poor thermal stability presents some difficulties. This method was validated by the analysis of the contamination of atmosphere, through volatilization by post-application processes, of atrazine in a parcel of 1 ha.     

Evaluation of reverse phase liquid chromatography/mass spectrometry for estimation of n-octanol/water partition coefficients for organic chemicals

A reverse-phase high pressure liquid chromatography/mass spectrometry (HPLC/MS method was developed for estimating n-octanol/water partition coefficients (K_ow) of anthropogenic molecules in complex chemical mixtures (e.g., complex effluents and solid waste leachates). The average error for an estimated log K_ow was ca. 0.5 and this error was similar for both aliphatic and aromatic compounds. The minimum level of detection using the total ion current profile generally decreased with increasing molecular weight between 100 and 600 daltons. Results obtained demonstrate that the HPLC/MS method is a viable technique for estimating log K_ow's of anthropogenic chemicals in complex environmental samples.     

Performance/Cost Estimates for Retrofitting Control Technologies

The U.S. EPA’s Air and Energy Engineering Research Laboratory is responsible for assessing control technology performance and costs under the National Acid Precipitation Assessment Program. A major part of this assessment involves developing site-specific estimates of the performance and costs of retrofitting SO₂ and NO_x control technologies for the top 200 SO₂- emitting (1980) coal-fired power plants in the 31-state eastern region. This effort includes detailed evaluation of a small number of plants (30 or less) representing a cross-section of the top 200 population. In cooperation with the states of Ohio and Kentucky (in conjunction with the U.S. EPA’s State Acid Rain Grant Program), efforts were undertaken to visit and conduct detailed evaluation of 12 coal-fired plants—five in Ohio, seven in Kentucky and the Tennessee Valley Authority System. A variety of commercial and advanced SO₂ and NO_x control technologies—including precombustion, combustion (in-furnace), and postcombustion (flue gas cleanup) technologies—were applied to each plant through conceptual designs. Retrofit factors (applied to the capital cost of a new pollution control system), cost “adders” (e.g., movement of existing equipment), and costs were developed for applying the control technologies to the boilers of each plant. Results of these and subsequent efforts will be valuable in evaluations of acid deposition control strategies by federal and state agencies and by electric utilities.     

MnOx/Al-SBA-15催化剂低温NH3选择性催化还原NO的原位红外研究简

用原位红外分别进行了MnO_x/Al-SBA-15催化剂上NH₃和NO+O₂的吸附态和瞬态实验以及NH₃+NO+O₂反应的稳态实验。结果表明,催化剂上存在着L酸位和B酸位,NH₃吸附在催化剂上形成配位态的NH₃和NH₄⁺,配位态的NH₃能脱氢形成—NH₂活性中间态。NO+O₂在催化剂上吸附形成硝酸盐类、硝基类和亚硝酸盐类。将NO+O₂通入预吸附NH₃的催化剂中时,表面的配位态的NH₃、NH₄⁺和—NH₂都会减少直至消失,SCR反应显著。而将NH₃通入预吸附NO+O₂的催化剂中时,只有硝基类和亚硝酸盐类减少,硝酸盐类基本不发生变化,SCR反应微弱。NH₃+NO+O₂稳态反应中,催化剂表面稳定存在着NH₄⁺和硝酸盐类,SCR反应显著。     

柱状V/AC催化剂的再生对脱硫活性的影响

使用常压固定床反应器,考察了吸附SO2的柱状V/AC催化剂的热再生和NH3再生行为.结果表明:柱状V/AC催化剂再生过程中生成的SO2主要沿催化剂轴向由内部向外扩散.催化剂350 ℃NH3再生的效率高于热再生的效率.两次热再生后柱状V/AC催化剂的脱硫活性开始下降,而六次NH3再生后的脱硫活性仍保持不变,甚至还稍高于新鲜柱状V/AC催化剂的脱硫活性.柱状V/AC催化剂孔结构和元素分析结果表明,NH3再生使催化剂表面含N官能团增加,保护了催化剂小于1 nm的微孔.     

Evaluation of GC-ion trap-MS/MS methodology for monitoring PCDD/Fs in infant formulas

The application of high resolution gas chromatography in combination with low resolution mass spectrometry with electron ionization and MS/MS detection (HRGC-MS/MS) is tested for its use in the analysis of PCDD/Fs in infant formulas. Development of the analytical method was based upon EPA directrices and international recommendations. Calibration linearity was tested and average relative response for any native and labelled compound over the five-point calibration range below 14% was found. The precision and accuracy of the proposed analytical procedure are also presented. Results obtained are in agreement with EPA criteria. The method is applied to the analysis of a number of initial and follow-on milk based infant formulas. In general, HRGC-MS/MS constitutes an interesting method for the analysis of dioxins in such matrices.     

Rapid PCDD/PCDF screening method for fly ash with ion trap MS/MS

A rapid screening method for the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) in fly ash has been developed. The screening is done in two steps: (a) the extraction by the accelerated solvent extraction and (b) the quantitative measurement by ion trap tandem mass spectrometer (MS/MS). Anhydrous sodium sulfate was added to the fly ash containing activated carbon in order to increase the extraction efficiency. The selectivity of the ion trap MS/MS was confirmed with 13C-labelled internal standard. Then the results of the screening method were compared with those obtained by the conventional analytical method using high-resolution mass spectrometer (HRMS).     

CuCoOx/TiO2催化氧化NO性能研究

采用浸渍法制备了CuCoOx/TiO₂催化剂,考察了焙烧温度、反应温度、氧含量、NO浓度和空间速度对催化剂催化氧化NO性能的影响,并考察了催化剂的抗硫抗水性能。XRD、TPR和BET分析表明,350℃焙烧的催化剂具有CuCo₂O₄尖晶石结构,比表面积大,对NO的氧化效果好。在空速为5 000 h^-1,NO进口浓度500 mg/m³,含氧量10%的条件下,反应温度300℃时NO转化率可达79.5%,250℃时NO转化率接近50%。该催化剂具有良好的单独抗SO₂、抗H₂O毒化性能,H₂O和SO₂同时存在时很快失活。该催化剂可用于不同时含H₂O和SO₂的含NO气体催化氧化后再吸收处理。     

Application of GC-MS/MS for the analysis of PCDD/Fs in sewage effluents

The application of high resolution gas chromatography in combination with tandem mass spectrometry in an ion trap was tested to substitute the expensive high resolution mass spectrometry in analysing polychlorinated dibenzo-p-dioxins and furans in sewage effluents. In tandem mass spectrometry, a set of parameters has to be optimised in order to attain the required sensitivity. To the best of our knowledge, this is the first time a method development for analysing PCDD/Fs with GC-MS/MS in an ion trap is described in this detail. Nine parameters are varied, including isolation window, collision induced dissociation (CID) amplitude, CID time, acquisition mass range, broadband amplitude, CID bandwidth, modulation range, filament current and ion trap temperature. This technique can be adapted to other analytes. By this optimisation, limits of detection of 0.01-0.05 ng/l are obtained. With its selectivity and sensitivity, tandem mass spectrometry is a powerful tool for the determination of PCDD/Fs in water samples. 55 sewage effluent samples from Germany were analysed.     

A2/O-MBR工艺处理印染废水中试研究

将平板微滤膜与A2/O工艺结合构建了A2/O-MBR中试系统,探讨了中试系统处理印染废水的效果及稳定性.结果表明,水解酸化可提高印染废水的可生化性,对COD平均去除率达到了43%.系统处理效果稳定,在最佳工况下COD、NH3-H和TN的去除率分别为88%、98%和80%.     

负载V2O5-WO3/TiO2掺炭纤维脱除烟气中Hg0

通过固定床实验系统研究烟气脱除零价汞的实验,首先研究了滤袋常用的聚苯硫醚（polyphenylene sulfide,PPS）以及活性炭纤维（activated carbon fiber,ACF）在不同温度、不同气体组分下负载V₂O₅-WO₃/TiO₂催化剂,对模拟燃煤烟气中零价汞（Hg⁰）的脱除效果。然后对比研究了活性炭纤维协同滤袋常用纤维负载催化剂后,对模拟燃煤烟气中Hg⁰的脱除性能。结果表明,在汞蒸气入口浓度为50 μg/m³,纯N₂气氛下,当温度为25℃时,两者脱除率均能达到99%,当温度为200℃,负载催化剂的活性炭纤维脱除率在30%左右,PPS纤维仅为10%左右。在200℃情况下,模拟烟气的组分为N₂+O₂时,2种纤维的Hg⁰脱除率提高了10%~20%,当在混合气体中添加0.01‰后,负载催化剂的PPS纤维Hg⁰脱除率能达到80%,活性炭纤维Hg⁰脱除率能达到98%。当温度为200℃,模拟烟气的组分为N₂+O₂+HCl时,不同性能掺炭纤维负载催化剂后Hg⁰脱除率在69%~95%范围之间变化,其中PPS掺炭纤维对Hg⁰脱除效率最高达到95%,因此,负载V₂O₅-WO₃/TiO₂催化剂的PPS掺炭纤维能在高温烟气中保持较高的Hg⁰脱除率。     

粗MnSO4溶液中MnS2O6的去除条件研究

用软锰矿吸收SO₂生成MnSO₄时会伴随有副产物MnS₂O₆生成。产品中MnS₂O₆的存在会降低硫酸锰产品质量,同时会缓慢释放出SO₂气体污染环境。本文用单因素实验方法研究了粗MnSO₄溶液中MnS₂O₆的最优去除条件。研究结果显示,软锰矿用量为12.2 g,硫酸加入量为20 mL、反应温度100℃、反应时间3 h、搅拌速度500 r/min,MnS₂O₆的去除率可达91%以上。其最终产品能达到GB1622-1986一级品标准。