Collaborative Research: Mechanistic study of mesoporous carbon formation from food waste

在美国，超过三分之一的食物都被浪费了。大约94%的被浪费的食物最终进入了垃圾填埋场、焚化炉和城市污水处理系统。在垃圾填埋场，食物垃圾的分解会产生温室气体（甲烷和二氧化碳）和其他可能导致土壤、空气和水污染的副产品。由于食物垃圾是有机碳的可再生来源，可以支持循环经济，因此迫切需要将食物垃圾转化为高价值产品的新颖且具有成本效益的工艺。该项目的总体目标是探索将无骨/均质食物垃圾转化为可用于制造超级电容器和储能应用的电极的介孔碳。为了实现这一目标，首席研究员（pi）建议设计、评估和优化一种新的两阶段工艺，该工艺由表面活性剂辅助水热碳化（HTC）食物垃圾生产碳氢化合物前驱体材料，然后热处理生产电极级介孔碳材料，用于制备具有高比表面积（2000 m2/g）和电容（275/F/g）的超级电容器。该项目的成功完成将通过产生新的数据和基础知识来促进将食物垃圾转化为用于超级电容器和储能应用的介孔碳，从而造福社会。通过学生教育和培训，包括指导老道明大学的一名研究生和南达科他州矿业与技术学院的一名研究生，将为社会带来额外的好处。食物垃圾是推进循环经济的有前途的资源和原料。然而，在将食物垃圾加工和转化为有价值的有机化合物的过程中，存在着一些挑战，包括食物垃圾的高水分含量、多变的成分和无机杂质的存在。水热碳化（HTC）是一种利用水作为反应介质，将食物垃圾转化为高价值有机产品的有前途的工艺。在这个项目中，首席研究员（pi）将探索利用表面活性剂协助HTC将均质和无骨的食物垃圾转化为碳氢化合物，然后对所产生的碳氢化合物进行热处理，以生成用于超级电容器和储能应用的电极级介孔碳。本研究的指导假设是：1)表面活性剂胶束在水热介质中的自组装将为食物垃圾在HTC过程中形成的分散的碳氢化合物提供成核和生长的场所；2)表面活性剂的使用将在热处理过程中打开碳氢化合物的孔隙，以改善介孔率、比表面积和离子嵌入。该研究的具体目标是：1)对表面活性剂辅助HTC过程中烃类形成的机理进行研究；2)开发和验证去除烃类中金属杂质的处理工艺；3)研究合成纯化后的碳氢化合物的化学热处理制备介孔碳；4)开展生命周期评估（LCA）和技术经济分析（TEA），以评估从食物垃圾中生产用于超级电容器制造和储能应用的介孔碳的环境影响和经济可行性。为了实现该项目的教育和培训目标，pi建议利用老道明大学（ODU）和南达科他州矿业与技术学院（SDSMT）的现有项目，1)从代表性不足的群体中招募和指导研究生和本科生参与该项目；2)开发和实施外展活动，以促进多样性、公平、并将其纳入STEM教育，包括在ODU和SDSMT举办的年度研讨会，重点关注食物垃圾转化为高价值产品的科学和工程。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。

Over one-third of the food produced in the United States goes to waste. About 94% of this wasted food ends up in landfills, incinerators, and municipal sewage systems. In landfills, the decomposition of food waste generates greenhouse gases (methane and carbon dioxide) and other by-products that can cause soil, air, and water pollution. Because food waste is a renewable source of organic carbon that can support a circular economy, there is a critical need for novel and cost-effective processes for converting food waste to high value products. The overarching goal of this project is to explore the conversion of boneless/ homogenized food waste into mesoporous carbon which could be used to fabricate electrodes for supercapacitors and energy storage applications. To advance this goal, the Principal Investigators (PIs) propose to design, evaluate, and optimize a novel 2-stage process which consists of a surfactant assisted hydrothermal carbonization (HTC) of food waste to produce a hydrochar precursor material followed thermal treatment to produce an electrode-grade mesoporous carbon material for preparing supercapacitors with high specific surface area (2000 m2/g) and electrical capacitance (275/F/g). The successful completion of this project will benefit society through the generation of new data and fundamental knowledge to advance the conversion of food waste to mesoporous carbon for supercapacitors and energy storage applications. Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student at Old Dominion University and one graduate student at the South Dakota School of Mines and Technology.Food waste is a promising resource and feedstock for advancing a circular economy. However, there are several challenges associated with the processing and conversion of food waste to valuable organic compounds including its high moisture content, variable composition, and the presence of inorganic impurities. Hydrothermal carbonization (HTC), which can utilize water as a reaction medium, has emerged as promising process for the conversion of food waste to high-value organic products. In this project, the Principal Investigators (PIs) will explore the ulization of surfactant assisted HTC to convert homogenized and boneless food waste to hydrochar followed by the thermal treatment of the produced hydrochar to generate an electrode-grade mesoporous carbon for supercapacitors and energy storage applications. The guiding hypotheses of the proposed research are that 1) the self-assembly of surfactant micelles in hydrothermal media will provide nucleation and growth sites for the dispersed hydrochar that forms during the HTC of food waste and 2) the use of a surfactant will open the pores of the hydrochar during thermal treatment to improve mesoporosity, specific surface area, and ion intercalation. The specific objectives of the research are to 1) conduct mechanistic investigations of hydrochar formation during surfactant assisted HTC; 2) develop and validate treatment processes to remove metallic impurities from hydrochar; 3) investigate the chemical-thermal treatment of the synthesized and purified hydrochar to generate mesoporous carbon; and 4) carry out a life cycle assessment (LCA) and techno-economic analysis (TEA) to evaluate the environmental impact and economic feasibility of producing mesoporous carbon from food waste for supercapacitor manufacturing and energy storage applications. To implement the education and training goals of the project, the PIs propose to leverage existing programs at Old Dominion University (ODU) and the South Dakota School of Mines and Technology (SDSMT) to 1) recruit and mentor graduate and undergraduate students from underrepresented groups to work on the project and 2) develop and implement outreach activities to advance diversity, equity, and inclusion in STEM education including annual workshops at ODU and SDSMT that focus on the science and engineering of food waste conversion to high value products.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.