Excellence in Research: Assessing the Electrospinning Behavior of Electrostatically Enriched Lignin Fractions

Agricultural residues are made of complex plant materials, primarily cellulose, hemicellulose, and lignin, which are tightly interwoven. Breaking them down efficiently and selectively is a key first step in biotechnology, as over 70% of their content consists of sugars that can be converted into bioethanol through chemical or enzymatic treatment and fermentation. However, these materials are naturally resistant to breakdown, making biofuel production challenging. To access the sugars, chemical pretreatments are used to separate the main components, but these processes consume large amounts of water, chemicals, and solvents, often damaging plant structures and producing harmful waste that threatens water quality. This project will explore dry fractionation as a sustainable and environmentally responsible alternative to conventional separation methods. Dry fractionation eliminates the need for chemicals and water, and generates no waste, while preserving structural integrity of key biopolymers. Results from the project could enable U.S. biorefineries to make special plant-based fibers at a significantly reduced cost compared with current methods. The project will help undergraduate and graduate students gain real-world experience in research, communication, and mentorship and receive industry feedback to make learning more relevant to modern bioprocessing needs. Additionally, the project will promote public engagement and STEM education through outreach activities like educational videos and a lignin nanofiber resource for students. By building stronger ties between universities and the biorefinery industry, the research will support innovation and collaboration that can drive sustainable technology development. This project will create a dry and chemical-free tribo-electrostatic separation (TES) method to separate agricultural biomass residues into two distinct fractions: a cellulose-rich fraction suitable for biofuel feedstock and a lignin-rich fraction to be further transformed into nanofiber biomaterials through electrospinning. These lignin-based nanofibers will potentially serve as effective adsorbents for organic contaminants and as components in supercapacitors. The overarching hypothesis is that cellulose's distinct surface properties and compositions compared to lignin and hemicellulose will result in different triboelectric charging behaviors, enabling their subsequent TES separation under an electric field. This research will 1) Investigate the relationship between triboelectric charging behaviors of biomass particles with their composition and physical properties; 2) Explore the TES separation behavior of biomass residues milled at varying particle sizes; 3) Assess the spinnability of electrostatically enriched lignin fractions for nanofiber production. Successful completion of this project will fill essential data gaps by investigating the tribo-charging behavior of biomass residues, enabling the development of completely dry, waste- and chemical-free TES while providing insight into critical factors affecting the purity of lignin-enriched fractions for nanofibers by electrospinning. 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.