Comparative Evaluation of Soda and Nitrate-Alkaline Pulping of Hemp, Flax, and Sisal Post-harvest Biomass.

As wood is still scarce in some countries, it is necessary to replace wood in the paper industry with other lignocellulosic raw materials, particularly agricultural residues. This study evaluated hemp, flax, and sisal postharvest biomass as alternative nonwoody fibrous feedstocks for pulp and paper production. Pulping was performed using soda and nitrate-alkaline methods under comparable degrees of delignification. Their suitability for papermaking was assessed in terms of mechanical properties, fiber sedimentation (rheosedimentation), and chemical parameters, including the degree of polymerization and the chemical composition of the raw material. The highest tensile strength was achieved for sisal, reaching 11.6 N m g-1 when produced by the soda method, which was higher than that of industrially produced flax or hemp soda pulps. Regarding pulp sedimentation behavior, hemp pulp showed significantly higher sedimentation rates, while comparable values were observed for recovered paper.