Interdisciplinary Study of Chemical and Transport Processes at a Plasma-Liquid Interface

该项目的重点是提高对发生在等离子体界面或界面附近的基本过程的理解，等离子体是由电子，离子和中性粒子组成的电离气体云，以及液体。在液体上方或内部产生的等离子体可以具有许多用途。 例如，等离子体放电已被用于对水、果汁和牛奶进行消毒，从水中去除有害化学物质，创造新材料，以及用于医疗应用。环境中发现的一些致癌污染物只能使用等离子体处理。在材料加工技术中，直接在不含水的液体（如酒精）中形成的等离子体可以将这些液体转化为不同的有用产品，包括碳纳米管，这是一种具有独特性能的材料，目前用于各种电子产品。更好地了解等离子体-液体界面附近的物理和化学过程不仅有助于改进现有的基于等离子体的过程，而且还将在生物医学、农业、能源、绿色化学和污染物缓解方面开辟新的应用。 等离子体-液体界面附近的区域表现出复杂的动力学，其取决于反应性自由基、离子和高能电子的形成，它们穿过界面的传输，以及用于混合和传输的体相流体运动的物理学。这些过程是相互关联的，包含物理和化学动力学。该研究项目的总体目标是确定在等离子体放电接触液体表面的系统中等离子体-液体界面处发生的物理和化学过程之间的关系。本研究的两个具体目标是：（1）相关的本体液体传输过程与等离子体-液体界面动力学和（2）确定的等离子体激发物种传输的界面过程的动力学的意义。实现这一多学科研究目标的方法是确定几种感兴趣的化合物的降解机制，并应用定量光学诊断工具（即粒子图像测速和激光诱导荧光）来了解界面处的物理特性以及散装液体运输在降解过程中的动力学作用。此外，将进行分子动力学模拟，以定量了解所研究的化合物在气液界面的微观结构。

This project focuses on improving the understanding of the fundamental processes that occur at or near interfaces of a plasma, a cloud of ionized gas composed of electrons, ions and neutral particles, and a liquid. A plasma that is created above or within a liquid can have a number of uses. For example, plasma discharges have been used to sterilize water, fruit juices, and milk, to remove harmful chemicals from water, to create new materials, and for medical applications. Some cancer-causing pollutants found in the environment can only be treated using plasmas. In material processing technologies plasmas formed directly in liquids that do not contain water, such as alcohols, can transform these liquids into different useful products including carbon nanotubes, a material with unique properties that is currently used in a wide variety of electronics. A better understanding of the physical and chemical processes near the plasma-liquid interface will not only help to improve the existing plasma-based processes, but will also open new applications in biomedicine, agriculture, energy, green chemistry and pollutant mitigation. The region near the plasma-liquid interface exhibits complex dynamics that depend on the formation of reactive radicals, ions and high energy electrons, their transport across the interface, and the physics of the bulk fluid motion for mixing and transport. These processes are interrelated and incorporate both physical and chemical dynamics. The overall goal of this research project is to determine relationships between the physical and chemical processes occurring at the plasma-liquid interface in a system where the plasma discharge contacts the liquid surface. Two specific goals of this study are to: (1) Correlate the bulk liquid transport processes with the plasma-liquid interface dynamics and (2) Determine the significance of the plasma excited species transport in the kinetics of interfacial processes. The approach for achieving the goals of this multidisciplinary study is to identify degradation mechanisms of several compounds of interest and apply quantitative optical diagnostic tools (i.e. Particle Image Velocimetry and Laser-Induced Fluorescence) to understand the physics at the interface as well as the role bulk liquid transport plays in the dynamics of the degradation process. Further, molecular dynamics simulations will be performed to develop a quantitative understanding of the microstructure of the studied compounds at the gas-liquid interface.