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，目前的流程产生的产品价值较低，这使得塑料回收在经济上缺乏吸引力。这个职业项目旨在提高人们对一种新的基于等离子的更新循环过程的理解，该过程将废弃的塑料转化为有价值的产品，帮助缓解日益严重的塑料污染，这种污染对世界人口的环境和健康产生了负面影响。这项研究计划的目标是分析等离子体(由带电粒子组成)在催化剂存在的情况下在常温水中分解塑料产生羧酸盐的机制，羧酸盐是一组可以很容易地用于生产高价值材料的含氧有机化合物。这项研究将为将广泛的废弃塑料转化为高价值化学品奠定基础，致力于采用循环报废方法来处理塑料污染。这一转变过程使用了一种低能量的等离子发电机，可以由风能和太阳能的可再生电力供电，使这一过程在经济上是可行的，并减少了其碳足迹。这项研究将与教育和推广计划相结合，以增加STEM中代表性不足的少数族裔和妇女的参与，并向STEM和非STEM专业的学生提供有关有益于环境的化学工艺的教育。这些活动将强调塑料回收利用对更健康的环境和可持续社会的重要性。用于包装的常见塑料，如聚乙烯、聚丙烯和聚苯乙烯，是惰性的，能够耐高温。因此，从废塑料中提取有用的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解聚过程的塑料转化的替代方法，该过程在常温和液态水中运行。这一过程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干的C-C键强度，然后在金属-有机骨架催化剂的存在下进行等离子体介导的解聚。本研究旨在1)用极性基团的顺序测量表面官能化的类型和程度对塑料解聚活性的影响，2)详细阐述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为STEM和非STEM专业的学生开发一门创新的跨学科本科课程--《赋予废弃塑料生命》，并采用SODOTO(See-One-Do-One-Teach-One)教学方法来培养学生的参与度、沟通能力和团队合作技能。除了这门课程，首席研究员还将设立暑期项目，向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，重点关注塑料升级循环的好处，并帮助激发人们对STEM职业的兴趣。课程和暑期活动将扩大国际学生联合会正在进行的努力，在中学阶段招收代表不足的少数族裔、女性和贫困学生。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.