EFRI E3P: Supercritical Extraction for the Elimination of End-of-Life Plastics (SCE3P)

多层塑料包装对于保持各种食品，包括肉类，果汁袋，奶酪和预制食品在运输和储存过程中的安全至关重要。为了发挥作用，多种材料一起使用，以满足单个材料无法满足的要求。然而，大多数多层食品包装最终都被填埋，因为目前的回收工艺无法将各种成分分离。在这个项目中，研究人员将使用高压和高温将气体转化为超临界流体，从而能够分离典型多层食品包装中使用的材料。所得较纯材料流的较高价值将改善回收多层结构的经济性。该过程将被设计为允许在现有回收工厂中常见的设备上直接实施。这项工作将包括对多层包装回收率提高的经济和环境影响进行全面评估。如果成功，该项目将产生新技术，提高塑料废物的可回收性，减少进入垃圾填埋场的塑料废物数量，并限制食品包装对环境的影响。该项目还将加强教育，多样性和劳动力的发展相结合的努力，从一个大的四年制大学，一个历史上的黑人大学，两年制社区学院在一个高度跨学科的方法来解决研究问题。参与研究的研究生和本科生将在合作机构进行交叉培训，并在开放日和地区教室开展有关聚合物、回收和相关科学的社区外展活动。该项目旨在通过一种旨在从多层食品包装中回收高价值阻隔聚合物并同时回收聚烯烃的工艺，使多层聚合物废物流增值。研究人员假设：1）超临界CO2与共溶剂组合，将通过增加溶剂相中的聚合物浓度和增强溶剂经由增塑渗透多层结构的能力来改善乙烯-乙烯醇（EVOH）和聚己二酰二苯二甲胺（MXD 6）从多层体系中的萃取，（二）改进挤出设备以使用超临界流体提供了几个优点，包括增强的层分离和溶解动力学以及降低的成本，包括总的再循环能量和回收设施改造费用，3）通过该过程回收的材料将适合用于闭环回收，以及4）拟议的技术将提高总体回收率，对环境产生净积极影响。这项工作将增加我们的热力学和动力学的理解的相行为的商业上重要的塑料和它们的混合物在超临界CO2与助溶剂。对溶剂选择、加工条件（例如，温度和压力），以及挤出机螺杆设计影响分配系数和聚合物萃取动力学。技术经济分析、生命周期评估、经济和环境影响分析将用于确定回收多层食品包装对环境的潜在影响，并确定政策工具的必要性，以促进这些材料的回收利用。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的支持。影响审查标准。

Multilayer plastic packaging is critical to keeping a wide range of food products, including meats, juice pouches, cheeses, and prepared foods, safe during transportation and storage. To function, multiple materials are used together to meet requirements that individual materials cannot. However, most multilayer food packaging winds up in landfills because current recycling processes cannot separate the various components. In this project, researchers will use high pressure and high temperature to turn gases into supercritical fluids that enable separating the materials used in typical multilayer food packaging. The higher value of the resulting purer material streams will improve the economics of recycling multilayer structures. The process will be designed to allow straightforward implementation on equipment commonly found at existing recycling plants. The work will include a thorough assessment of both the economic and environmental impacts of increased recycling rates for multilayer packaging. If successful, the project will result in new technology that increases the recyclability of plastic waste, reduces the amount of plastic waste entering landfills, and limits the environmental impact of food packaging. The project will also enhance education, diversity, and workforce development by combining efforts from a large four-year university, a historically black university, and a two-year community college in a highly interdisciplinary approach to addressing the research questions. Graduate and undergraduate students participating in the research will cross-train at the partner institutions and develop community outreach activities on polymers, recycling, and related science for use at open houses and area classrooms.This project aims to valorize the multilayer polymer waste stream through a process designed to reclaim high-value barrier polymers from multilayer food packaging and simultaneously recycle the polyolefins. The investigators hypothesize: 1) supercritical CO2, in combination with cosolvents, will improve the extraction of ethylene vinyl alcohol (EVOH) and polyxylylene adipamide (MXD6) from multilayer systems by increasing the polymer concentration in the solvent phase and enhancing the solvent's ability to penetrate the multilayer structure via plasticization, 2) modifying extrusion equipment to use supercritical fluids offers several advantages including enhanced layer separation and dissolution kinetics and reduced costs including overall recycling energy and recycling facility retrofitting expenses, 3) the materials reclaimed by this process will be suitable for use in closed-loop recycling, and 4) the proposed technology will increase overall recycling rates, having a net positive environmental impact. The work will increase our thermodynamic and kinetic understanding of the phase behavior of commercially important plastics and their mixtures in supercritical CO2 with cosolvents. Fundamental understanding of how solvent choice, processing conditions (e.g., temperature and pressure), and extruder screw design impact partition coefficients and polymer extraction kinetics will be gained. A combination of techno-economic analysis, life-cycle assessment, and economic and environmental impact analysis will be used to establish the potential impact of recycling multilayer food packaging on the environment and determine the need for policy instruments to promote the recycling of these materials.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.