CAREER: Detailing the mechanism of plasma-mediated oxidative depolymerization of plastics to chemicals by metal-organic frameworks in liquid water at ambient temperature

塑料回收的一个核心问题是，目前的工艺生产的产品价值低，使得塑料回收在经济上没有吸引力。这个CAREER项目旨在提高对一种新的基于等离子体的升级循环过程的理解，将废弃塑料转化为有价值的产品，帮助减轻对环境和世界人口健康产生负面影响的日益严重的塑料污染。该研究计划的目标是分析等离子体（由带电粒子组成）在催化剂存在下在室温水中分解塑料以产生羧酸盐的机制，羧酸盐是一组含氧有机化学品，可用于生产高价值材料。这项研究将为将各种废弃塑料转化为高价值化学品奠定基础，并致力于采用循环的方法来处理塑料污染。转换过程使用低能量等离子体发生器，该发生器可以由风能和太阳能的可再生电力供电，使该过程在经济上可行并减少其碳足迹。这项研究将与教育和推广计划相结合，以增加在STEM中代表性不足的少数民族和妇女的参与，并教育STEM和非STEM专业的学生了解有利于环境的化学过程。这些活动将强调塑料升级回收对更健康的环境和可持续发展的社会的重要性。常见的包装塑料，如聚乙烯，聚丙烯和聚苯乙烯，是惰性的，能够承受高温。因此，从废塑料中提取有用材料通常需要能源密集型措施，如热解，将塑料转化为烷烃类化合物。该项目的目标是开发一种基于催化等离子体介导的解聚过程的塑料转化替代方法，该过程在环境温度和液态水中运行。该方法首先对废塑料表面进行改性，以增加其润湿性并降低聚合物主链C-C键强度，然后在金属-有机骨架催化剂存在下进行等离子体介导的解聚。拟议的研究旨在1）测量极性基团序列的表面功能化的类型和程度对塑料解聚活性的影响，以及2）详细说明等离子体辅助解聚的机理并分析对羧酸盐产物的选择性。该项目的教育计划重点是开发一门创新的跨学科本科课程，“为废弃塑料赋予生命”，专为STEM和非STEM专业设计，并结合SODOTO（See-One-Do-One-Teach-One）教学方法，以培养学生的参与，沟通和团队合作技能。除了课程外，首席研究员还将开设暑期课程，向具有不同背景的学生介绍化学概念，强调化学如何帮助解决环境问题，重点关注塑料回收的好处，并帮助激发对STEM职业的兴趣。该课程和暑期活动将扩大PI的持续努力，在中学招收代表性不足的少数民族，妇女和贫困学生。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

A central problem in plastic recycling is that current processes yield low-value products, making plastic recycling economically unattractive. This CAREER project seeks to improve understanding of a new plasma-based upcycling process for transforming discarded plastic into valuable products, helping to mitigate the ever-increasing plastic pollution that negatively impacts the environment and health of the world’s population. The objectives of this research program are to analyze the mechanism whereby a plasma (consisting of charged particles) breaks down plastic in ambient-temperature water in the presence of a catalyst to produce carboxylates, a group of oxygen-containing organic chemicals that can readily be used to produce high-value materials. This research will lay the groundwork for transforming a broad range of discarded plastic into high-value chemicals, working toward a circular end-of-life approach for dealing with plastic pollution. The transformation process uses a low-energy plasma generator that can be powered by renewable electricity from wind and solar sources, making the process economically viable and reducing its carbon footprint. This research will be integrated with educational and outreach programs to increase engagement of underrepresented minorities and women in STEM, and to educate both STEM and non-STEM majors about chemical processes that can benefit the environment. These activities will emphasize the importance of plastic upcycling for a healthier environment and a sustainable society.Common plastic for packing, such as polyethylene, polypropylene, and polystyrene, is inert and capable of withstanding high temperature. Thus, derivation of useful materials from waste plastic normally requires energy-intensive measures, such as pyrolysis, that convert plastic to alkane-like compounds. The objective of this project is to develop an alternative approach to plastic conversion based on a catalytic plasma-mediated depolymerization process that operates at ambient temperature and in liquid water. This process begins with modification of the waste plastic surface to increase its wettability and to reduce the polymer backbone C-C bond strength, followed by plasma-mediated depolymerization in the presence of a metal-organic framework catalyst. The proposed research seeks to 1) measure the effects on plastic depolymerization activity of the type and extent of surface functionalization with sequence of polar groups, and 2) detail the mechanisms of plasma-assisted depolymerization and analyze selectivity towards carboxylate products. The project’s education plan centers on developing an innovative interdisciplinary undergraduate course, “Giving Life to Discarded Plastics” designed for STEM and non-STEM majors and incorporating the SODOTO (See-One-Do-One-Teach-One) method of teaching to build student engagement, communication, and teamwork skills. In addition to the course, the principal investigator will institute summer programs that introduce chemistry concepts to students with diverse backgrounds, emphasizing how chemistry can help address environmental problems, focusing on the benefits of plastic upcycling, and helping to inspire interest in STEM careers. The course and summer initiatives will expand the PI’s on-going efforts to recruit underrepresented minorities, women, and underprivileged students at the secondary level.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.