2021 Annual Meeting
Green Solvent Extraction of Betulin from the Birch Bark
The majority of plastic products seen on the market are sourced from fossil-fuel derived polymers. The use of alternative feedstocks will allow for decreased dependence on fossil fuels as well as potentially offer other benefits such as increased polymer functionality and biodegradability. One promising bio-based monomer is betulin, a molecule commonly found in birch bark. Birch bark removed from the forest industry is potentially a plentiful, underutilized and regenerable source for bio-based plastic. This research seeks to optimize betulin extraction from dried, milled birch bark using green solvents and processes. The betulin yield and selectivity for reflux boiling (RB) with select green organic solvents and supercritical carbon dioxide assisted extractions (SFE) with green co-solvents is compared. Based on liquid chromatography-mass spectrometry analysis, the average yield of SFE was approximately 13% higher than that of RB. Precipitation of the solvent extract with water resulted in high purity solids betulin recovery. Furthermore, the betulin content in different species of birch tree is also compared. The reflux boiling products obtained from experiments under the same extraction conditions using different barks showed that the betulin concentration in locally sourced silver birch (Betula Pendula) is approximately 25% higher than that of locally sourced river birch (Betula Nigra), and Betula Nigra has a higher content of betulinic acid and lupeol. These results provided a preliminary understanding on the potential of green solvents in the betulin extraction and polymerization process, which will be the development basis for more rigorous analysis and larger scale experiments.