GOALI: Unipolar Diffusion Charging of Spherical and Agglomerated Nanoparticles and its Application toward Surface-area Measurement

GOALI：球形和团聚纳米颗粒的单极扩散充电及其在表面积测量中的应用

• 批准号: 1236107
• 负责人: David Y.H. Pui
• 金额: $ 30万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236107&HistoricalAwards=false
• 关键词: GOALI; Unipolar; Diffusion; Charging; Spherical

CBET-1236107Many important properties of nanoparticles are related to their extremely high surface to volume ratios, including catalytic activity, bioavailability, health effects, and reactivity in the environment. This project studies the fundamental unipolar charging mechanics of nanoparticles and their agglomerates/aggregates. By combining unipolar charging and electrostatic deposition to develop an instrument, it will enable online measurement of the geometric surface area of airborne nanoparticles with various morphologies. Thus far it is only possible to measure the so-called Fuchs or BET surface area, which do not provide information about the geometric surface area of airborne particles.The research will perform fundamental studies on diffusion charging mechanisms. Investigated particle sizes will be from several hundred nanometers down to below 20 nm for spheres, and below 80 nm for agglomerates and aggregates. Charging rates between the loose agglomerates and partially sintered aggregates will be determined experimentally and theoretically. Instrument developmental effort will be performed at both UMN and TSI laboratories, which will involve: (1) offline determination of the surface area of the agglomerates and aggregates, (2) investigation of the combination of charging and electrostatic deposition for the measurement of particle surface area, which will incorporate the Electrostatic Precipitator (ESP) developed by our German collaborators, and (3) overall response of the charger, ion trap and ESP for agglomerates and aggregates. The charge distributions and electrostatic deposition efficiencies of agglomerates are different from those of spheres. Our study will elucidate principal dependencies of charging and electrostatic deposition on particle morphology.Intellectual Merit and Broader Impacts:This proposed study will advance understanding of the effects of particle morphology on unipolar charging and electrostatic deposition of nanoparticles. This will help to develop a method for online measurements of total geometric surface area of spherical and agglomerated nanoparticles. Such a method can have a wide range of applications since fast and online nanoparticle surface area measurement is desirable in process control of nanoparticle manufacturing, in dosage determination for nanoparticle toxicity studies, in exposure measurement and many other applications. It will play an important role in studying environmental, health and safety (Nano-EHS) implications of engineered nanoparticles. The Nano-EHS issues will be prominent in society and is the theme of the just released NRC Report on Research Strategy for Environmental, Health, and Safety Aspects of Engineered Nanomaterials (2012). David Pui serves on the Advisory Board of two EU Nano-EHS programs: SCAFFOLD and NANODEVICE. Last year, he served on the Advisory Board of the 5th International Symposium on Nanotechnology, Occupational and Environmental Health, and was a panelist of the Roundtable Discussion on Assessment of Nanoparticle Exposure in Occupational Settings at the Society of Toxicology Annual Meeting. During the past two years, he presented seven plenary lectures at various international symposia on the Nano-EHS topic. Results obtained from this research project will be disseminated through these outreach channels. We also plan to integrate the knowledge into our teaching activities. For example, David Pui is involved in the teaching of a joint public affairs, law and bioethics course on Nanotechnology and Society (PA 8790/Law 6037/BTHX 8000 course at the University of Minnesota).

CBET-1236107纳米颗粒的许多重要特性与其极高的表面积与体积比有关，包括催化活性、生物利用度、健康影响和环境反应性。本项目研究纳米颗粒及其团聚体/聚集体的基本单极充电机制。通过结合单极充电和静电沉积来开发仪器，它将能够在线测量具有各种形态的空气中纳米颗粒的几何表面积。到目前为止，它只能测量所谓的Fuchs或BET表面积，这并不提供有关空气中颗粒的几何表面积的信息。这项研究将进行扩散充电机制的基础研究。研究的颗粒尺寸将从几百纳米下降到低于20纳米的球体，并低于80纳米的团聚体和聚集体。松散团聚体和部分烧结骨料之间的充电速率将通过实验和理论确定。仪器开发工作将在UMN和TSI实验室进行，包括：（1）离线测定团聚体和聚集体的表面积，（2）研究用于测量颗粒表面积的充电和静电沉积的组合，其将结合由我们的德国合作者开发的静电蒸发器（ESP），以及（3）充电器、离子阱和ESP对附聚物和聚集物的总体响应。团聚体的电荷分布和静电沉积效率与球形颗粒不同。我们的研究将阐明充电和静电沉积对粒子形态的主要依赖关系。智力优点和更广泛的影响：这项拟议的研究将促进了解粒子形态对单极充电和静电沉积的纳米粒子的影响。这将有助于开发一种在线测量球形和团聚纳米颗粒的总几何表面积的方法。这种方法可以具有广泛的应用，因为快速和在线的纳米颗粒表面积测量在纳米颗粒制造的过程控制中、在纳米颗粒毒性研究的剂量确定中、在暴露测量中和许多其他应用中是期望的。它将在研究工程纳米颗粒的环境，健康和安全（Nano-EHS）影响方面发挥重要作用。纳米EHS问题将在社会中突出，是刚刚发布的NRC报告的主题，关于工程纳米材料的环境，健康和安全方面的研究战略（2012年）。大卫裴担任两个欧盟纳米EHS计划的顾问委员会：SCAFFOLD和NANODEVICE。去年，他担任第五届国际纳米技术研讨会的顾问委员会，职业和环境健康，并在毒理学年会的社会在职业环境中的纳米颗粒暴露评估的圆桌讨论会的一个成员。在过去的两年里，他在各种国际研讨会上就纳米EHS主题发表了七次全体演讲。将通过这些外联渠道传播这一研究项目的成果。我们还计划将这些知识融入我们的教学活动中。例如，大卫贝是参与联合公共事务，法律和生物伦理学纳米技术和社会课程（PA 8790/法律6037/BTHX 8000课程在明尼苏达大学）的教学。