Birch sawdust as a valuable side stream for platform chemicals. The effect of microwave- and ultrasound-assisted treatments on sawdust and its conversion
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
L3, University of Oulu, Linnanmaa
Topic of the dissertation
Birch sawdust as a valuable side stream for platform chemicals. The effect of microwave- and ultrasound-assisted treatments on sawdust and its conversion
Doctoral candidate
Master of Science Salla Kälkäjä
Faculty and unit
University of Oulu Graduate School, Faculty of Technology, Research unit of Sustainable Chemistry
Subject of study
Chemistry
Opponent
Professor Janne Jänis, University of Eastern Finland
Custos
Docent Katja Lappalainen, University of Oulu
Sawdust to future building blocks: utilizing microwaves and ultrasound for the valorization of recalcitrant wood residues
Sawdust is still often burned for energy, even though it could serve as a starting material for new bioproducts. In this doctoral research, sawdust was treated with microwaves and ultrasound — environmentally friendly technologies that break down the structure of wood and promote chemical reactions toward platform chemicals such as furfural and 5-hydroxymethylfurfural (HMF). The reactions were carried out in an aqueous deep eutectic solvent, which proved to be surprisingly effective at the laboratory scale for processing such a demanding raw material as sawdust — converting sugars into these compounds is typically much easier. The result was a set of valuable platform chemicals that can be used in the production of e.g. biofuels, plastics, and pharmaceuticals.
The study explored how microwave and ultrasound treatments affect birch sawdust. The goal was to enhance the conversion of sugar compounds derived from sawdust into furfural and HMF. According to the findings, both treatments improved the reactivity of sawdust and promoted the formation of these chemicals. In particular, the combination of ultrasound and dilute acid treatment led to effects that may be beneficial in future applications.
This research shows that side streams from the wood industry can be used to produce valuable platform chemicals without heavy or environmentally harmful methods. Although scaling up the process will require further research and optimization, the results offer hope that fossil-based raw materials could be increasingly replaced with renewable ones — especially underutilized industrial side streams.
The study explored how microwave and ultrasound treatments affect birch sawdust. The goal was to enhance the conversion of sugar compounds derived from sawdust into furfural and HMF. According to the findings, both treatments improved the reactivity of sawdust and promoted the formation of these chemicals. In particular, the combination of ultrasound and dilute acid treatment led to effects that may be beneficial in future applications.
This research shows that side streams from the wood industry can be used to produce valuable platform chemicals without heavy or environmentally harmful methods. Although scaling up the process will require further research and optimization, the results offer hope that fossil-based raw materials could be increasingly replaced with renewable ones — especially underutilized industrial side streams.
Last updated: 15.10.2025