Promising methods for lignin isolation

The joint project "SmartRecovery to boost lignin commercialization" between V TT and Aalto University has reached its final stage. Launched in January 2023, the project, funded by Business Finland and participating partner companies, aimed to promote the commercial utilization of lignin. It involves biorefineries, technology developers, and end users.

"The starting point was to develop bio-based alternatives to fossil products, for which lignin is well suited. Often, traditionally isolated lignin needs to be modified after isolation to make it easily usable. In the project, we developed new lignin isolation methods so that we could directly get it into a suitable form for various applications," says the researcher who is the project manager of the project. Miriam Kellock VTT reports. 

Lignin for batteries

During the project, work has been done with various biomasses. Particularly promising results were obtained with kraft lignin isolated from black liquor, a by-product of pulping.

“Kraft lignin isolated using membrane technology is very suitable for the production of hard carbon, and hard carbon produced by carbonizing lignin performs as well in lithium-ion battery tests as the corresponding commercial hard carbon.”

Lignin was isolated from wheat bran by precipitation after organosolv digestion, and the research focused on how the isolation conditions affect the quality of the lignin produced. Lignin isolated by this method could be used, for example, in bio-based adhesives.

Easier quality control

The quality of biomass varies, and the quality of the lignin obtained from it can vary considerably depending on, for example, the origin of the raw material and the isolation conditions, so it is important to be able to measure different properties.

“Traditional analysis methods are laborious, so we developed rapid characterization methods that use spectral analysis and modeling to efficiently obtain a wealth of information about lignin properties.”

In addition, the environmental impacts and commercial potential of the processes were assessed.

“The life cycle analysis gave good results especially for the kraft lignin process, meaning that the insulation method we developed is more environmentally sustainable than the method currently in common use.”