We are all familiar with the Brothers Grimm story of a goblin that can convert a biobased resource, straw, into gold. This action would be the prototypical definition of upcycling – taking a lower value resource and creating new, higher-value materials. While this fairytale of gold from plant materials is far from reality, the idea of upcycling is an important one for the emerging bioeconomy. For example, during the chemical pulping of wood for papermaking, lignin is removed from the cell wall and transferred into the pulping liquor.
Upcycling Lignin
Lignin has an important structural function for the tree, but once extracted it is typically burned in the pulping liquor to recover the energy content. This process helps in the recycling of pulping chemicals and provides energy for the paper-making process. However, many companies have been considering recovering a portion of this lignin from the pulping liquor to upcycle it. Industry is looking into new biobased materials that could help the bottom-line of the company by providing a suite of potentially carbon-neutral bioproducts. Moreover, stored carbon in materials is increasingly being recognized as an important component when addressing climate change.
In the Advanced Renewable Materials Laboratory, we have been spinning lignin into fibrous materials with interesting characteristics. For example, by using a process of electrospinning – where high voltage is used to help draw fibre smaller than a spider silk filament – the lab forms tissue-like nonwoven materials with lignin that is 100-1000x smaller in diameter than a human hair. Nonwoven fibre is a type of entangled fibre material usually used in applications such as medical gowns or some reusable grocery bags. It has recently been of global interest because nonwoven fibers are a critical layer in N95 masks. Post-doctoral fellow, Dr MiJung Cho has been leading the effort of spinning lignin since doing her PhD when she studied the spinning and carbonization of lignin for composite applications. After completing her PhD, she went on to create an ingenious method to make shape-memory 3-D foam-like materials from this fibre, requiring no other additives. She currently holds a fellowship to work with a consortium of BC’s pulp and paper companies (BC BioAlliance) and has been conducting research on the conversion of lignin from BC pulp mills into filtration media to determine if they would be effective in blocking the passage of small particles.
Applications for this Research
While tiny electrospun fibres are known to be excellent for filtration media with their large amount of surface area, the Advanced Renewable Materials Laboratory received a NSERC COVID-19 Alliance grant to research if lignin fibres have anti-viral capacity. The Lab includes collaborators in Wood Science, Chemistry, Chemical and Biological Engineering, CHBE, and Biochemistry. If successful, the Lab is excited to contribute research that may help create personal protection equipment. Canada’s pulp and paper sector would have a specific application that could quickly turn lignin into “gold”. Hence, if the fibres are shown to be effective in filtration and can be scaled-up efficiently, the research would meet the triple bottom-line of sustainability by impacting the social, environmental, and economic outcomes.
Scott Renneckar is the Canada Research Chair in Advanced Renewable Materials and program director of Forest Bioeconomy Sciences and Technology. He can be reached at scott.renneckar@ubc.ca. MiJung Cho is a postdoctoral fellow at the Advanced Renewable Materials Lab. She can be reached at mijung.cho@ubc.ca.
