Researchers at Karlstad University have started a 3-year project focusing on greener manufacturing and increased recycling of forest-based materials. They already have extensive knowledge about the chemical processes involved in providing product properties that determine the possibility of recycling. The new project is about transferring that knowledge to an industrial scale.
– In previous research projects, we have looked at the chemical processes during dewatering and drying that affect the recycling of cellulose-based materials, says Björn Sjöstrand, docent in Chemical Engineering. It is about temperature and water content through the manufacturing process and we have carried out studies on a laboratory scale. Through a research grant from ÅForsk, we now have the opportunity to continue our studies and see how we can transfer the methods from our laboratories to an industrial scale.
Hornification
One of the problems with recycling these materials is that wood fibers become stiffer during the dewatering and drying processes, also referred to as hornification. The same also happens to, for example, dish cloths, which become stiffer every time they get wet and then dry. Manufacturing of cellulose-based materials always requires a lot of water, which makes studying hornification very interesting.
– Previous studies have taught us at what levels of dryness the hornification begins, already at dry contents as low as 20 percent, which corresponds to 80 percent water content, says Björn Sjöstrand. We also know at what temperatures the hornification begins, already at as little as 40°C. However, the biggest differences occur at higher drying temperatures than 100°C. The solvent also plays a role, if we replace the water in the paper pulp with other liquids, the hornification is reduced. This implies that the hydrogen bonds that sometimes form in the water environment contribute to the hornification of the fibres.
Increased circularity
Greater insight into the process of hornification has many advantages. The research can hopefully contribute to new dewatering processes for the paper industry, which in turn will create more recycling opportunities and improved product properties. If we manage to understand the hornification process better, the energy use and the amount of raw materials required can also be reduced. Knowledge of hornification is useful in all different manufacturing processes of cellulose-based materials.
– We’re now continuing the work of understanding and improving the processes of dewatering, drying and recycling wood fibers and cellulose-based materials, says Björn Sjöstrand.
The new three-year project has received SEK 2 million in funding through ÅForsk, which is a foundation promoting research and development.
More information: Hornification in Commercial Chemical Pulps: Dependence on Drying Temperature, BioResources 2024
