CRAEMS: Fundamental Studies of Nanoparticle Formation in Air Pollution

伍斯特理工学院获得了环境分子科学合作研究活动奖（creems），该奖项由化学部门的特别项目办公室支持。Barbara Wyslouzil因对空气污染中纳米颗粒形成的基础研究而获得该奖项的支持。还通过次级奖励向特拉华大学的Doug Doren、Murray Johnston、Wang Hai和Anthony Wexler提供支持。一项综合实验和理论计划将在分子水平上理解与空气污染有关的纳米颗粒形成过程。将讨论的主题是(1)在水系统中的成核，(2)烟灰的形成，以及(3)燃烧过程中烟灰和金属之间的相互作用。在超声速喷管中产生水、水/酒精和水/硝酸气溶胶，并用小角中子散射和红外光谱对其进行表征。分子模拟技术将应用于计算成核速率和解决重要的非平衡效应。烟尘颗粒将产生在一个平面火焰燃烧器和表征取样与扫描迁移率粒度仪。尺寸分布将与小角中子和x射线散射实验所得的结果进行比较。粒子的分子组成将用质谱法测定。金属和烟灰之间的反应将通过从乙烯-氧火焰中产生颗粒来研究，并播种二茂铁。数学模型将发展，结合分子机制的金属氧化物颗粒形成和碳沉积。颗粒成核是许多环境和工业过程中的关键步骤。耐火颗粒是在燃烧和冶金过程中形成的，而酸性水滴是在烟囱气体、火山烟雾和大气中的光化学反应中产生的。这项研究将有助于确定它们形成的机制以及它们在空气污染中所起的作用。

This Collaborative Research Activities in Environmental Molecular Science (CRAEMS) Award to Worcester Polytechnic Institute is supported by the Special Projects Office in the Chemistry Division. Barbara Wyslouzil is supported by this award for the fundamental study of nanoparticle formation in air pollution. Support is also provided to Doug Doren, Murray Johnston, Hai Wang, and Anthony Wexler at the University of Delaware through subawards. An integrated experimental and theoretical program will be carried out to understand, at a molecular level, the processes of nanoparticle formation that are relevant to air pollution. The topics that will be addressed are (1) nucleation in aqueous systems, (2) soot inception, and (3) the interaction between soot and metals during combustion. Water, water/alcohol and water/nitric acid aerosols will be generated in a supersonic nozzle and characterized by small angle neutron scattering and FTIR. Molecular simulation techniques will be applied to calculate nucleation rates and to address important non-equilibrium effects. Soot particles will be generated in a flat flame burner and characterized by sampling with a scanning mobility particle sizer. Size distributions will be compared to those derived from small angle neutron and x-ray scattering experiments. Molecular composition of the particles will be determined by mass spectrometry. The reaction between metals and soot will be studied by generating particles from ethylene-oxygen flames, seeded with ferrocene. Mathematical models will be developed that incorporate molecular mechanisms of metal oxide particle formation and carbon deposition.Particle nucleation is a key step in many environmental and industrial processes. Refractory particles are formed in combustion and metallurgical processes, while acid-water droplets are produced in stack gases, volcanic plumes and in photochemical reactions in the atmosphere. This research will help define the mechanisms by which they are formed and the role they play in air pollution.