Washington State University researchers have developed a way to practically separate lignin from wood, a breakthrough that could provide new sources of lignin for advanced renewable fuel and advanced materials applications.
The work is featured on this week’s cover of the journal Green Chemistry.
Lignin is the second most abundant renewable carbon source on Earth. It is in all vascular plants, where it forms cell walls and provides plants with rigidity. Lignin allows trees to stand, gives vegetables their firmness and makes up about 20-35 percent of the weight of wood.
The material holds great promise as a precursor for biobased materials and fuels, but it is also notoriously difficult to break apart.
The wood products industry has been struggling for a century to make valuable market products from lignin. The material is usually separated from wood during papermaking and biorefining processes, but these often contaminate the lignin and significantly alter its chemical and physical properties, decreasing its value. So most lignin is burned to produce fuel and electricity.
Led by Xiao Zhang, associate professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, the WSU researchers used a new type of solvent to separate the lignin from wood without altering its key properties. The researchers were able extract lignin from poplar and Douglas fir samples in high yields. The lignin products have high purity and distinct characteristics.
The researchers are still working to understand the solvent’s precise mechanism for separating the lignin. They are exploring new applications for this type of lignin and are in discussion with industry partners regarding scaling up production.
“Finding a way to extract a large quantity of lignin with limited chemical modifications from woody biomass can provide a breakthrough in realizing lignin’s potential,’’ said Zhang.
The work was supported through a National Science Foundation career grant (award no. 1454575) and the U.S. Department of Agriculture National Institute of Food and Agriculture (grant no. 2011-68005-30416 administered through the Northwest Advanced Renewables Alliance (NARA)).
WSU Gene and Linda Voiland School of Chemical Engineering and Bioengineering, phone: 509-372-7647
WSU Voiland College of Engineering and Architecture communications