(413c) Multi-Stream Integrated Bioproducts Enabled By Biorefinery Lignin Waste Fractionation

Authors: 
Li, Q., Texas A&M University
Hu, C., Texas A&M University
Li, M., Texas A&M University
Yuan, J., Texas A&M University
Multi-stream Integrated Bioproducts Enabled by Biorefinery Lignin Waste Fractionation

Qiang Li1,2*, Cheng Hu1,2, Mengjie Li1,2, Joshua S. Yuan1,2*

1Synthetic and Systems Biology Innovation Hub, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA

2Department of Chemical Engineering, Texas A&M University, College Station, TX 77843, USA

*For correspondence: Qiang Li: liqerlee@tamu.edu; Joshua S. Yuan: syuan@tamu.edu

Lignin represents the main waste stream in lignocellulosic biorefinery. Valorizing lignin into fungible value-added bioproducts is one of the most challenging issues for modern biorefinery. Nevertheless, the conversion and quality of bioproducts heavily depend on the polymer chemistry of lignin. In particular, the fundamental relationship between the chemistry of lignin polymer and the performance of the resultant bioproducts needs to be defined. In our research, we targeted on high value bioproducts like carbon fiber, asphalt binder modifier and bioplastics, which have great potential to transform the bioeconomy and implement modern biorefinery. Our basic research concept is that lignin with different chemical characteristics is suited for different bioproduct manufacturing. The hypothesis is that lignin chemistry could be tuned to integrate multiple bioproducts manufacturing. To validate the hypothesis, we have developed a series of lignin fractionation technologies, including biological system using laccase-mediator, organic solvent extraction, physical separation, and pH precipitation to regulate lignin chemical linkages, functional groups, molecular weight, and molecular uniformity. Basically, we have found that lignin with more linear β-O-4 linkage, less hydroxyl groups, higher molecular weight and uniformity enhanced the crystallite growth in carbon fiber and thus is more suitable for making strong carbon fiber. Meanwhile, lignin with smaller molecular weight significantly improved the bacterial fermentation efficiency and bioplastic production. In addition, lignin with higher hydroxyl groups and lower molecular weight improved high temperature performance of asphalt binder without compromise of its low temperature performance. Based on these fundamental understanding, we further designed sequential fractionation to derive different lignin fractions with unique chemical characteristics to make multiple bioproducts of carbon fiber, bioplastics, and asphalt binder modifier. The qualities of the three products have been synergistically enhanced. The technical breakthroughs thus paved the avenue to integrate multi-stream bioproducts from biorefinery lignin waste toward a cost-effective and sustainable modern biorefinery.