NIRT: Combustion-Generated Nanoparticles: The Role of Transition Metals in Nanoparticle and Pollutant Formation

燃烧产生的纳米颗粒——过渡金属在纳米颗粒和污染物形成中的作用cts -0404314。燃烧产生的金属氧化物纳米颗粒在主要含碳纳米颗粒的形成/生长中的作用。金属氧化物凝聚在生长的纳米颗粒上形成有机污染物的作用。镍和铜已被确定为初步研究的重要金属。它们的氧化物在一系列条件下的反应性正在使用各种实验技术进行研究。枝晶合成技术用于制造1-3纳米的金属氧化物纳米颗粒，有或没有相关的碳质层；溶胶-凝胶技术用于在碳和二氧化硅上制造金属氧化物薄膜。利用高温流动反应器，结合GC-MS、EPR和FTIR分析，研究了有机化学品与这些纳米颗粒替代物在200 ~ 1100℃的氧化和热解条件下的反应。采用高效液相色谱-紫外吸收法研究了金属催化多环芳烃的形成。利用LSU同步加速器设施的x射线光谱技术表征了金属氧化物的性质及其化学结合。从头算建模技术用于评估纳米颗粒的几何形状，反应位点，可能的反应机制，以及它们如何随颗粒大小和金属特性而变化。据估计，美国每年有超过65万人因接触空气中的细颗粒物而过早死亡。PM2.5被定义为空气动力学平均直径小于2.5微米的颗粒，已被证明会在暴露于PM2.5的人群中引发心肺疾病和癌症。然而，直到最近人们才意识到，亚微米的燃烧产生的纳米颗粒（单独或与其他污染物一起）可能是造成大多数死亡和相关疾病的原因。尽管美国国立卫生研究院和美国环保署已经启动了对健康影响的研究项目，但致病因子仍然未知，而且由于缺乏对燃烧产生的纳米颗粒的复杂组成和反应性的了解，进展受到阻碍。该计划的推动力是实际的，即了解燃烧产生的纳米颗粒的起源和性质，以便将其对环境的影响降至最低。其目标是有助于了解影响燃烧产生的纳米颗粒对健康影响的化学因素，以便通过燃烧控制减轻或消除其影响。

NIRT: Combustion-Generated Nanoparticles--The Role of Transition Metals in Nanoparticle and Pollutant FormationCTS-0404314 This project addresses: 1.) The role of combustion-generated metal oxide nanoparticles in the formation/growth of primarily carbonaceous nanoparticles and 2.) The role of metal oxides condensed on growing nanoparticles in the formation of organic pollutants. Ni and Cu have been identified as important metals for initial study. The reactivity of their oxides under a range of conditions is being studied using a variety of experimental techniques. Dendrimeric synthesis techniques is used to create 1-3 nm metal oxide nanoparticles with and without associated carbonaceous layers; sol-gel techniques are used to create thin metal-oxide films on carbon and silica. The reactions of organic chemicals with these nanoparticle surrogates from 200 to 1100 C under oxidative and pyrolytic conditions are studied using a high-temperature flow reactor coupled with GC-MS, EPR, and FTIR analysis. Metal-catalyzed PAH formation is studied using HPLC-UV absorption. The nature of the metal oxides and their chemical binding is characterized using x-ray spectroscopic techniques at the LSU synchrotron facility. Ab initio modeling techniques are used to assess nanoparticle geometries, reaction sites, possible reaction mechanisms, and how they may vary as a function of particle size and metal identity. It has been estimated that over 650,000 people die prematurely in the US each year due to exposure to airborne fine particles. PM2.5, defined as particles with a mean aerodynamic diameter of less than 2.5 microns, have been shown to initiate cardiopulmonary disease and cancer in exposed populations. It has been realized only recently, however, that submicron, combustion-generated nanoparticles are the likely cause (alone or in combination with other pollutants) for the majority of these deaths and associated illnesses. Although health-effects research programs have been initiated by NIH and EPA, the causative agents remain unknown and progress is hindered by lack of understanding of the complex composition and reactivity of combustion-generated nanoparticles. The impetus of this program is practical, viz. to understand the origin and nature of combustion-generated nanoparticles so that their environmental impact can be minimized. The goal is contribute to the understanding of the chemical factors impacting the health effects of combustion-generated nanoparticles so that their effects can be mitigated or eliminated through combustion control.