Preparation of marine-sourced alginate fibres to produce composite paper from both green and blue carbons

Recent trends in papermaking have led to an increase in the use of alternative resources. Alginate fibres, derived from marine sourced brown seaweed (blue carbon), offer a potential alternative to wood pulp in paper production. The process of obtaining alginate involves pre-treatment, alkaline extraction, precipitation, and purification. Through successful extraction, alginates were obtained from Laminaria japonica (L. japonica) and Sargassum polycystum (S. polycystum) with yields ranging from 17.4% to 28.9% and 14.7% to 26.8%, respectively. The molecular mass of the alginates ranged from 0.68 × 10⁵ to 2.74 × 10⁵ g mol⁻¹ for L. japonica and from 0.39 × 10⁵ to 0.994 × 10⁵ g mol⁻¹ for S. polycystum. Calcium alginate fibres and wood pulp fibres were combined to create composites. The results from this study suggest that the composites achieved an optimum tensile index when the samples contained 50% calcium alginate fibres. Although the results were promising, the tensile index of the paper made exclusively from pulp fibres remained superior. Furthermore, thermal degradation tests demonstrated improved thermal stability for the composite papers compared to hardwood bleached kraft pulp (HBKP) sheets. In conclusion, a composite prepared from a mixture of calcium alginate and wood pulp fibres was successfully produced and overall 50% inclusion of calcium alginate fibres provided an optimum composite.