Valorization of Biomass and Waste Plastics for Sustainability

Speaker :
Prof. Xiangian BAI
Associate Professor of Mechanical Engineering and the Department of Chemical and Biological Engineering at Iowa State University
Date : 15 Dec 2023 (Fri)
Time : 9:30 - 10:30 am
Venue : LT-G, HKUST


My research group’s focus is the valorization of low-cost feedstock such as biomass and waste plastics to fuels, chemicals, and materials for energy and environmental sustainability. In this talk, I will describe our research progress on developing low-cost carbon-based materials from biomass residues. Carbon fiber is popular in many applications, but its widespread application is hindered by its high production cost. Although lignin is a promising low-cost alternative precursor, the low tensile properties of lignin-based carbon fiber have been a bottleneck and barrier. To overcome the intrinsically defected lignin structure not having molecular linearity, we proposed a “deconstruction followed by controlled reconstruction” concept to transform lignin into a linear thermoplastic precursor. An arylate thermoplastic polymer synthesized from lignin bio-oil was melt-spun to obtain carbon fibers with a tensile strength of 1.7GPa and tensile modulus of 182GPa. More recently, we developed a thermochemistry and mechano-chemistry integrated fabrication method to manipulate the lignin structure. Based on this novel method, we achieved carbon fibers with an unprecedented tensile strength of 2.45 GPa and tensile modulus of 236 GPa using sole lignins without chemical pretreatment. Other than carbon fibers, we also developed biobased carbon nano-onion. Carbon nano-onion is a relatively new member of nanocarbons, having broader potential applications in biomedicals, energy storage, sensors, and more. However, its fossil-based precursors, harsh synthesis conditions, and extremely high costs (>$1M/ton) prevent its broader applications. We developed a robust electricity-based method to synthesize oxygen-functionalized carbon nano-onions from biochar or lignins agnostic to feedstock type. We found that 0.1-0.5wt% of biobased carbon nano-onions in PLA can significantly improve the mechanical, thermal, and gas barrier properties of the biobased polymer, far outperforming other carbon-based additives or fillers, including carbon nanotubes. 


Dr. Xianglan Bai is an Associate Professor of Mechanical Engineering and the Department of Chemical and Biological Engineering at Iowa State University. She is also the Associate Chair of Research in the Department of Mechanical Engineering. Dr. Bai received her BS and MS in Human, Machine, and Environment Engineering from the Beijing University of Aeronautics and Astronautics (BUAA), China, and a Ph.D. in Mechanical Engineering from the University of Tokyo, Japan. After working as a postdoc at Michigan State University and research engineer at a company, Dr. Bai joined Iowa State University as a tenure-track Assistant Professor in 2013 and was promoted to Associate Professor with tenure in 2019. Dr. Bai’s research interests include renewable energy and sustainability, especially on biobased products, upcycling of waste plastics, and efficient CO2 capturing/utilization via developing novel transformative conversion technologies and advanced manufacturing. Dr. Bai’s research has been supported by federal funding agencies and industrial sponsors with more than $13M in research grants since 2013. Dr. Bai’s work has been published in over 50 research articles and two book chapters. She has also filed 6 US patents and patent applications based on her research at Iowa State University.  Dr. Bai’s research has been frequently selected as the Editor’s Choice Articles in Journals and Best Posters in International conferences. Further information about Dr. Bai’s technical background and research activities is available at