ICP-MS法测定PM2.5中无机元素浓度及污染特征分析

采用微波消解、电感耦合等离子体质谱(ICP-MS)法同时直接测定了PM_2.5中23种无机元素的浓度,并对消解方法、ICP-MS工作参数及条件进行了优化和选择。该方法的检出限为0.01~10.00 ng/mL,定量检出限为0.04~40.00 ng/mL。采用该方法测定了2017年10月—2018年1月秋冬季唐山市3个监测点位的PM_2.5滤膜样品,结果表明:地壳元素中Si浓度最高,为2.30 μg/m³,大多元素浓度在采暖前高于采暖后;重金属元素中Zn浓度最高,为0.48 μg/m ³,大多元素浓度在本次观测的11月和12月较高;所测元素浓度与其他文献数据具有可比性,说明该方法适用于环境大气PM_2.5中的无机多元素分析测试。     

黄铁矿的光催化及其辉光放电等离子体催化降解水体中泰乐霉素的性能对比

黄铁矿的异相Fenton和半导体特性使其具有良好的污染物降解潜力。基于黄铁矿的光催化技术和辉光放电等离子体技术可以同时利用这2种特性。但目前仍缺乏对这2种技术降解抗生素废水的对比研究。因此,考察了黄铁矿参与的2种高级氧化技术(AOP)对泰乐霉素(tylosin tartrate,TYL)的降解效果、机制、产物、适用条件和经济成本。结果表明,2种技术在pH=3~11内对TYL均有稳定的降解性能。黄铁矿光催化技术对TYL的降解效率(99%)要明显高于黄铁矿耦合等离子技术(56.33%),但其矿化效果却低于等离子技术。2种反应体系中的·OH、h⁺、·O₂⁻以及e⁻均参与到TYL的降解中。其中,在黄铁矿光催化体系中·OH、h⁺和·O₂⁻是TYL降解的主要活性物种。活性物种主要通过光催化与Fenton反应生成。而在黄铁矿耦合等离子体体系中,e⁻在TYL降解中发挥的作用则更为突出。与黄铁矿光催化相比,黄铁矿耦合等离子体中e^−*的产生为TYL的降解提供了更多的活性物种。2种催化降解技术对TYL的降解过程相似。TYL经过水解、C-O键断裂、去羟基、去甲基、C=O、C-N断裂、开环后最终被矿化为H₂O和CO₂。在相同实验条件下,黄铁矿耦合等离子体技术对TYL的处理效能要优于光催化技术。以上研究结果有助于更好地理解黄铁矿参与的高级氧化技术对污染物的降解机理,并为难降解的抗生素类污染物的处理提供参考。     

Effluents from MBT plants: Plasma techniques for the treatment of VOCs

Mechanical–biological treatments (MBTs) of urban waste are growing in popularity in many European countries. Recent studies pointed out that their contribution in terms of volatile organic compounds (VOCs) and other air pollutants is not negligible. Compared to classical removal technologies, non-thermal plasmas (NTP) showed better performances and low energy consumption when applied to treat lowly concentrated streams. Therefore, to study the feasibility of the application of NTP to MBTs, a Dielectric Barrier Discharge reactor was applied to treat a mixture of air and methyl ethyl ketone (MEK), to simulate emissions from MBTs. The removal efficiency of MEK was linearly dependent upon time, power and specific input energy. Only 2–4% of MEK was converted to carbon dioxide (CO₂), the remaining carbon being involved in the formation of byproducts (methyl nitrate and 2,3-butanedione, especially). For future development of pilot-scale reactors, acting on residence time, power, convective flow and catalysts will help finding a compromise between energy consumption, desired abatement and selectivity to CO₂.     

焊接作业厂房烟尘扩散规律研究与响应面分析

为研究焊接烟尘在多因素耦合作用下的扩散规律，通过在某小型焊接车间进行实验，将不同温度、湿度、风速3种影响因素进行耦合分析，测定不同环境条件下焊接车间内的烟尘浓度。采用Design Expert软件进行Box Behnken实验设计，构建电焊焊接烟尘浓度在3因素3水平条件下的二次回归响应曲面模型，通过研究二次模型实验因素间交互作用，了解二次项对烟尘浓度影响因素的排序，并简要分析电焊烟尘的治理措施。研究结果表明:温度、湿度、风速3个因素均为显著影响；二次项显示因素影响RhV（相对湿度与风速）>TRh（环境温度与相对湿度）>TV（环境温度与风速）。     

Preparation of MgO/B2O3 coatings by plasma spraying on SUS304 surface and effects of heat-resistant

This study mainly deals with the preparation of MgO/B₂O₃ coatings by plasma spraying on the SUS304 surface and the effects of heat-resistant. The power materials of low thermal conductivity were selected to control the heat divergent performance of high temperature parts. The reticular micro-structure between the cover thermal layer and the substrate was prepared by using the plasma spraying method. The powder mixture of MgO and B₂O₃ were selected as spraying materials and the SUS304 was used as the substrate material. The MgO/B₂O₃ coating was prepared on the surface of the SUS304 to provide better cover thermal performance. The properties of the microstructures and the morphologies were studied by Optical Microscope, Scanning Electron Microscope, Electron Probe Microanalyzer, and X-ray Diffraction. The results showed that the cover thermal performance has been improved.     

离子液体氯化1-辛基-3-甲基咪唑对EMT6细胞的毒性及其机理研究

为评估咪唑类离子液体的生物毒性,研究了氯化1-辛基-3-甲基咪唑([C8mim] [C1])对EMT6细胞的毒性作用和可能的机制.不同浓度(0.06、0.25、1 mmol·L-)的[C8 mim][Cl]对EMT6细胞染毒12h后,采用MTT方法检测细胞活力,二乙酸荧光素(FDA)方法检测细胞膜通透性的变化,Rhodamine 123染色方法检测线粒体膜电位的变化,ELISA方法检测了Caspase-3的活性,并测定了细胞内活性氧(ROS)的含量.结果表明,经[Csmim] [Cl]染毒12h后,EMT6细胞活力下降,并呈剂量依赖关系.当[Csmim] [Cl]浓度高于0.25 mmol·L-1时,细胞活力与对照相比,差异显著.研究还发现,[Csmim][Cl]染毒增加了EMT6细胞膜通透性,降低了线粒体膜电位并诱导产生过量的活性氧,增强了Caspase-3活性.实验结果表明,[C8mim] [Cl]染毒造成了EMT6细胞膜通透性的改变、活性氧的过量产生和凋亡分子表达的增强,这可能是[Csmim] [Cl]导致细胞凋亡和活力下降的主要原因.     

Simultaneous measurement of tool torque,traverse force and axial force in friction stir welding

Simultaneous measurement of the tool torque, traverse force and axial force during friction stir welding process is of great significance to the understanding of the underlying process mechanism and the optimizing of the process parameters. Different from the traditional measurement methods using load cell or rotating component dynamometer, an indirect but economical methodology is used in this study for the simultaneous measurement of the traverse force, axial force and tool torque by monitoring the output torques of the servo motors and main spindle three-phase AC induction motor inside the FSW machine. The values of the traverse force, axial force and tool torque are determined under different welding conditions, and the influencing factors are examined. The measured results in friction stir welding of AA2024-T4 aluminum alloys at different combinations of tool rotation speed and welding speed lay foundation for process optimization.     

脉冲电晕放电等离子体去除污染土壤热脱附尾气中的DDTs

为探索新型产业化应用热脱附尾气处理技术,采用脉冲电晕放电等离子体技术对含DDTs的热脱附尾气进行处理,考察了工艺参数如脉冲电压、脉冲频率、ρ（DDTs）和停留时间对DDTs处理效果的影响,分析了DDTs经低温等离子体处理后的分解产物.结果表明,DDTs的去除率随脉冲电压的升高、脉冲频率的增大和停留时间的延长而增加,随进气中ρ（DDTs）的升高而降低,但去除量随进气中ρ（DDTs）的升高而增大.进气中的ρ（DDTs）为30.0 mg/m3,停留时间为10 s,脉冲电压为30.0 kV,脉冲频率为50 Hz时,DDTs的去除率为82.5%.低温等离子体处理后,尾气中的ρ（p,p'-DDT）、ρ（o,p'-DDT）和ρ（p,p'-DDD）降低,ρ（p,p'-DDE）反而升高,另有微量的二苯甲烷、二苯甲醇、4,4'-二氯二苯甲烷、2,4'-二氯苯甲酮和1,1-双（对氯苯）-2-氯乙烯等分解产物被检出.研究显示,脉冲放电等离子体技术具有去除效率高等特点,可有效去除含DDTs的热脱附尾气.      

脉冲电晕烟气脱硫脱硝的化学动力学分析

对脉冲电晕等离子体条件下烟气ＳＯ２、ＮＯ气相氧化进行化学动力学模拟研究，结果表明，在气相反应中，ＳＯ２主要由ＯＨ基氧化脱除，大部分氧化物转化为Ｈ２ＳＯ４；ＮＯ的氧化则涉及与多种自由基（Ｏ，ＯＨ，ＨＯ２）及中性物种的反应，给出了ＳＯ２、ＮＯ气相氧化对主要自由基（ＯＨ基）浓度的依赖关系，以及典型实验上ＳＯ２气相净化所需的最优ＯＨ基产额，讨论了Ｈ２Ｏ和Ｏ２的行为和作用，及其含量对气象净化过程的影响；化学     

Dissolved metal ion removal by online hollow fiber ultrafiltration for enhanced size characterization of metal-containing nanoparticles with single-particle ICP-MS

Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations, however, coexisting dissolved metal ions greatly interfere with the accuracy of particle size analysis. The purpose of this study is to develop an online technique that couples hollow fiber ultrafiltration (HFUF) with SP-ICP-MS to improve the accuracy and size detection limit of MCNs by removing metal ions from suspensions of MCNs. Through systematic optimization of conditions including the type and concentration of surfactant and complexing agent, carrier pH, and ion cleaning time, HFUF completely removes metal ions but retains the MCNs in suspension. The optimal conditions include using a mixture of 0.05 vol.% FL-70 and 0.5 mmol/L Na₂S₂O₃ (pH = 8.0) as the carrier and 4 min as the ion cleaning time. At these conditions, HFUF-SP-ICP-MS accurately determines the sizes of MCNs, and the results agree with the size distribution determined by transmission electron microscopy, even when metal ions also are present in the sample. In addition, reducing the ionic background through HFUF also lowers the particle size detection limit with SP-ICP-MS (e.g., from 28.3 to 14.2 nm for gold nanoparticles). This size-based ion-removal principle provided by HFUF is suitable for both cations (e.g., Ag⁺) and anions (e.g., AuCl₄⁻) and thus has good versatility compared to ion exchange purification and promising prospects for the removal of salts and macromolecules before single particle analysis.