Wood pulp could replace fossil materials in synthetic chemical manufacture

Finnish and UK scientists develop method for making lignin particles react with enzymes in water, opening up new possibilities for bio-based polymers from wood

Finland is covered in forests, and as a result the pulp and paper sector is one of its most important industries. One of the byproducts of the pulp industry is lignin, the fibrous organic polymer that gives wood its structural strength but must be removed when it is turned into paper. Currently, lignin has no commercial uses, and is treated as a waste material.

Trying to find a use for this waste stream, researchers at Aalto University joined forces with the Green Chemistry Centre of Excellence at York University. The research concentrated on the behaviour of spherical particles of lignin, whose manufacture had already been developed at Aalto. Their major breakthrough was in creating a water-repellent composite structure out of the lignin particles, when they discovered that, by regulating the surface charge of the particles, they could make enzymes stick to their surface. The researchers used a natural polymer isolated from seaweed to support the lignin-enzyme complexes.

wood pulp

The biocatalysts (at the bottom of the vial) could open new avenues in green synthesis (Image: Valeria Azovskaya)

As the researchers explain in a paper in Nature Communications, these complexes had surprising properties. The lignin improved the efficiency of the reaction catalysis performed by the enzymes, enabling reactions that would not otherwise work in water.

Aalto University postdoctoral researcher Mika Sipponen explains that this could have a major commercial significance. “The commercial enzyme we use as reference is attached to the surface of synthetic acrylic resin produced from fossil raw materials. In comparison, this new biocatalyst was at best twice as active,” he said. “The beauty of this method lies in its simplicity and scalability. We are already able to manufacture lignin particles in batches of several kilogrammes. Of course, we hope that this will become a sustainable option for the enzyme industry to replace fossil materials in technical applications.”

The discovery could open up new possibilities for the production of biologically-based polyesters, the team claims. “We are pleased that the years of investing in the lignin particle research are beginning to produce significant results. We envision several possible uses for spherical particles in green chemistry processes and the development of new materials”, said research leader Professor Monika Österberg.