Bark of Norway spruce is generated as a side-product of the forestry products industry in large amounts, every year approximately 1.5 million tons are produced in Sweden. Since there is renewed interest into bio-based and renewable materials to replace fossil-based materials the forestry industry has gained attention. Thus, it is important to use the raw materials from the forest as efficient as possible, also the side-products. A biorefinery concept was applied to develop new materials and find value-added applications for the different components that can be extracted from the spruce bark. Extractives, pectin, hemicellulose, cellulose and lignin are separated by mild extraction processes and investigated. In this work functionalized nanocellulose was derived from the bark by a chlorine-free delignification and preparation of cellulose oxalate powder in a solvent-free process, from which the nanocellulose can be isolated by sonication. This represents an economic and environmentally advantageous way of applying the biorefinery concept. The chemical composition and thermal properties of the components during the extraction and separation steps were examined and cellulose oxalate powder was obtained in high yield. The morphological structure of the nanocellulose, prepared from the cellulose oxalate powder, was characterized and it was found to be a mixture of rod-like nanocrystals and nanofibrils. The results show that the bark is a potential inexpensive source of high-value nanocellulose that can be used in cosmetics or as reinforcement in nanocomposites. In future work, the combination of the nanocellulose with other components from bark to form “all-bark” composites will be investigated.

Valorization of Norway spruce bark by a biorefinery concept into new materials

ACS Spring Meeting 2021

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