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Accelerated Chemistry In Aerosol Droplets Relevant To The Atmosphere

与大气相关的气溶胶液滴中的加速化学反应

基本信息

批准号：
1904765
负责人：
Murray Johnston
金额：
$ 48.94万
依托单位：
University of Delaware
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1904765&HistoricalAwards=false
关键词：
Accelerated Chemistry Aerosol Droplets Relevant

项目摘要

The Environmental Chemical Sciences Program of the Division of Chemistry supports Professor Murray Johnston of the University of Delaware to investigate chemical reactions in aerosol droplets that may contribute to formation of organic particulate matter in the atmosphere. The main health impacts of air pollution arise from ozone and particulate matter. This project studies how water in airborne particles can assist formation of organic particulate matter from volatile organic compounds in ways that are not readily predicted by studying chemical reactions in bulk aqueous solution. This project also contributes to the development of the scientific workforce through graduate student training in an environment that encourages multidisciplinary innovation and public outreach. An aerosol flow reactor is used to study chemical reactions on the surface of aqueous ammonium sulfate droplets that combine two volatile monomer reactants to give a nonvolatile dimer product. These reactions include aldehyde-aldehyde reactions to produce an aldol, aldehyde-alcohol reaction to produce a hemiacetal, and alcohol-acid reaction to produce an ester. The reactor system has the ability to precisely control initial droplet size and composition including water content, ionic strength and acidity. Systematic control of these variables provides insight into reaction mechanisms. Intermediates and products of the reactions are characterized and, where possible, quantified with a variety of online mass spectrometry methods. These methods include elemental analysis with the nano aerosol mass spectrometer, which gives a measure of droplet acidity based on the nitrogen-to-sulfur mole ratio, and molecular analysis with droplet assisted ionization and extractive electrospray ionization. Students supported by the project are broadly trained in environmental chemistry, analytical chemistry and nanoscience. They bring environmental topics to the attention of scientists and non-scientists alike through various outreach events.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

化学系的环境化学科学项目支持特拉华大学的默里·约翰斯顿教授研究气溶胶液滴中的化学反应，这些化学反应可能有助于大气中有机颗粒物的形成。空气污染对健康的主要影响来自臭氧和颗粒物。该项目研究空气中颗粒中的水如何帮助挥发性有机化合物形成有机颗粒物质，其方式是通过研究散装水溶液中的化学反应而不易预测的。该项目还通过在鼓励多学科创新和公众宣传的环境中培训研究生，促进科学劳动力的发展。气溶胶流动反应器用于研究硫酸铵水滴表面的化学反应，这些化学反应将两种挥发性单体反应物结合在一起，产生非挥发性二聚体产物。这些反应包括醛-醛反应生成醛醇，醛-醇反应生成半缩醛，醇-酸反应生成酯。反应器系统具有精确控制初始液滴大小和组成的能力，包括含水量、离子强度和酸度。对这些变量的系统控制提供了对反应机制的洞察。反应的中间体和产物被表征，并在可能的情况下用各种在线质谱方法进行定量。这些方法包括使用纳米气溶胶质谱仪进行元素分析，该质谱仪根据氮硫摩尔比测量液滴酸度，以及使用液滴辅助电离和萃取电喷雾电离进行分子分析。该项目支持的学生在环境化学、分析化学和纳米科学方面接受了广泛的培训。他们通过各种外展活动将环境问题引起科学家和非科学家的注意。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。