Engineered invasive plant cellulose fibers as resources for papermaking.
Seven fast-growing invasive plant species were harvested in Slovenia and tested for their valorisation potential in the pulp and paper industry with the aim of sustainable substitution of commercial cellulose fibres. Cellulose fiber materials were isolated by filtration after solubilizing extractives, lignin and hemicellulose in a kraft pulping process. The chemical structure was thoroughly studied, as well as the optical, morphological and mechanical properties. All examined species (Ailanthus altissima, Fallopia bohemica, Fallopia japonica, Rhus typhina, Robinia pseudoacacia, Rudbeckia laciniata and Solidago canadensis) contain relatively high amount of C6 polysaccharides (> 35%), have notable hemicellulose content (30-40%), low ash content (< 2%) and can be easily delignified, while manufactured natural fibers exhibit convenient morphology (fiber length 0.47-0.88 mm; width 14.4-20.9 μm), optical (ISO whiteness 19.0-36.0%) and mechanical characteristics (tensile index 18.0-58.0 Nm/g; tear index 0.8-4.1 mN m2/g; and burst index 0.5-2.4 kPa m2/g indices), which makes them applicable to sustainable paper production. The pulp yields varied between 34-44%, where both darker herbaceous and brighter woody fibers were morphologically comparable to typical hardwoods. According to the observed properties Robinia pseudoacacia and Rudbeckia laciniata seem to be superior raw material for commercial papermaking products. The ubiquitous invasive plants pose a huge potential for the circular economy, especially in terms of their cascade valorisation of biorefinery by the isolation and valorization of hemicellulose, sugars, and lignins into added-value aromatic and aliphatic building blocks. However, promising yield of cellulose fibers of decent morphology and mechanical properties are reported in this study.