In my last column, I wrote about a process that turns waste hop biomass into nanofibers. Good news! Another group of scientists have learned how to turn hazelnut shells into a potential renewable energy source. Isn’t science neat?
Researchers at the Heilongjiang Academy of Agricultural Machinery Sciences in China have been focusing on the chemical properties and antioxidant activity of wood vinegar and tar fraction in bio-oil produced from hazelnut shell pyrolysis (the thermal decomposition of materials at elevated temperatures in an inert atmosphere) from about 750º – 1,800º F.
Wood vinegar can be used in fields as insect repellent, fertilizer and plant growth promoter or inhibitor, and can be applied as an odor remover, wood preservative and animal feed additive. The study’s lead author, Liu Xifeng, said the wood vinegar and tar from the hazelnut shells could also be used for energy, as the two substances left over after burning the shells contained phenolic substances (which when diluted can also be used as disinfectants).
The researchers conducted their experiments in a tube furnace pyrolysis reactor, and hazelnut shell samples weighing 20 grams were placed in the waiting area of a quartz tube in advance. When the target temperature was reached, the shells were pushed to the reaction region and heated for 20 minutes.
To separate two fractions of bio-oil sufficiently, the liquid product was centrifuged at 3,200 revolutions per minute for eight minutes. The resulting aqueous fraction was called wood vinegar. The separated tar fraction remained stationary for 24 hours without the appearance of a liquid phase. Both the wood vinegar and tar were stored in sealed tubes for analysis.
The research team learned pyrolysis temperature had a significant effect on the yield and properties of wood vinegar and tar fraction in the bio-oil from hazelnut shells. Wood vinegar was the dominant liquid fraction, with maximal yield of 31.23 weight percent obtained at 1,300º, attributable to the high concentration of water.
In a nutshell (get it?), this new research lays the groundwork for even more applications of bio-oil from waste hazelnut shell pyrolysis. As more growers raise hazelnuts, hopefully we’ll continue to find new ways to use as much of the plant as possible.