Hibiscus cannabinus and Hibiscus sabdariffa as an alternative pulp blend for softwood: Optimization of soda pulping process

Abstract

Due to dearth of forest based raw materials paper technocrats have explored the possibility of alternate cellulosic fibrous raw materials. H. cannabinus and H. sabdariffa—agro-based residues bear the characteristics of both, the softwood and hardwood fibers. The bast fibers of H. cannabinus and H. sabdariffa underneath the bark resemble with softwood and core fibers with hardwood. Morphological analysis and chemical composition of H. cannabinus and H. sabdariffa show their suitability for producing paper of various grades. This study provides optimized soda pulping conditions for better utilization of H. cannabinus and H. sabdariffa. Due to identical pulping conditions, H. cannabinus and H. sabdariffa can be delignified together. The optimum cooking conditions for H. cannabinus and H. sabdariffa were found to be as, active alkali 18% (as NaOH), temperature 165C, time (at temperature) 180 min and wood to liquor ratio of 1:4.5. An AQ dose of 0.05% at an active alkali dose of 13% (as Na₂O) produces the screening rejects and kappa number similar to that obtained by using 15% active alkali (as Na₂O).