While biomass is typically used as an energy source, like its fossil-based counterpart, researchers are also keen to evaluate its potential to produce new materials. Recently, a team of researchers from the University of Delaware (UD) has reported findings of an innovative low-pressure method that upcycles biomass into new sustainable materials.
Published in the journal Science Advances, lead author Professor Thomas H. Epps III, explains “This work demonstrates the potential of technical lignin as an inexpensive and abundant resource for producing value-added chemicals and materials and a scalable valorization pathway for feedstock selection, intensified deconstruction, product fabrication, and economic evaluation.”
While it is widely accepted that we are in need of sustainable new materials to address some of the current issues related to the environment and climate, unless the materials are scalable and cost-effective, they will not have a practical impact. This is why the UD researchers are considering the economics of upcycled biomass materials.
Lignin belongs to a group of complex organic polymers that are found in key structural materials in the support tissues of most plants. Lignins are crucial in the establishment of cell walls, particularly in wood and bark, because they do not rot easily and they are rigid.
However, lignin is also a waste product – known as technical lignin – that is generated during industrial processing in the pulp and paper industry. One thousand million tons of technical lignin are generated annually. However, it is considered difficult to reuse due to contamination and, as a result, is typically burned for heat or used as a filler for rubber tires.
However, Epps and his team believe there is more to technical lignin than meets the eye and that there is value potential to such an abundant resource. In their research, they demonstrate the potential to convert technical lignin into high-performance plastics, which can be used in applications such as additive manufacturing (3D printing).
The ability to take something like technical lignin and not only break it down and turn it into a useful product, but to do it at a cost and an environmental impact that is lower than petroleum materials is something that no one has really been able to show before.
Professor Thomas H. Epps III, Lead Author
Optimizing the Conversion Process
With economic factors playing a central role in their research, Epps and his team wanted to overcome some of the expensive hurdles associated with upcycling lignin. One of the main issues is that most existing processes that can be used to upgrade lignin require high pressures making them hard to scale and expensive.
Other significant issues and concerns surrounding existing industrial techniques is safety and energy consumption associated with the solvents, temperatures and pressures used in the process. To tackle these issues, the UD team used glycerin (rather than methanol) so that the process could be conducted at normal ambient temperatures.
Glycerin is also cost-effective and found in everyday items such as soaps, shampoo and cosmetics. In this process, it is valued for its ability to break down the lignin into the necessary chemical building blocks for making bio-based materials such as resins for 3D printing, bioplastics, and other compounds such as antioxidants.
While operating at ambient pressures makes the process a lot safer, it also eliminates the necessity for a closed system which opens up the possibility for conducting simultaneous reaction and separation steps. This means it is much easier to upscale the process and create more materials at a faster, cheaper rate.
Amongst the UD team was Paula Pranda, co-lead author, who helped optimize the conversion process by collaborating with co-author Yuqing Luo to model the system for its economic feasibility. While it was known the process was physically possible, making it cost-effective was another determining factor.
It shows there is a lot of potential for using renewable resources to make different types of plastics. You don’t have to use fossil fuels, plastics from renewable resources can be economically feasible, too.
Paula Pranda, Co-Lead Author
Producing materials derived from waste biomass could go some way to addressing some of the issues surrounding sustainability and preservation of natural resources. Additionally, upcycling biomass could revolutionize various industrial manufacturing processes of consumer products that typically derive from fossil-based materials.
References and Further Reading
Roberts, K., (2022) Creating value from waste | UDaily. [online] Udel.edu. Available at: https://www.udel.edu/udaily/2022/january/biomass-lignin-to-plastics-chemicals-can-be-economical/
O’Dea, R. and Pranda, P., et al., (2022) Ambient-pressure lignin valorization to high-performance polymers by intensified reductive catalytic deconstruction. Science Advances, [online] 8(3). Available at: https://www.science.org/doi/10.1126/sciadv.abj7523