Potential of C. citriodora wood species for kraft pulp production

This work characterizes the wood from Corymbia citriodora for pulp production. We evaluated wood chip samples from an 8-year-old C. citriodora plantation. A sample of Eucalyptus grandis x Eucalyptus urophylla chips from a 7-year-old plantation was used as reference material. Wood fiber morphology and chemical composition were analyzed. A modified kraft pulping was carried out to achieve kappa 18 on brownstock pulps. After that, pulps were oxygen delignified, and then underwent elemental chlorine free (ECF) bleaching to achieve the target brightness of 90±0.5% ISO. The bleached pulps were refined in a PFI mill at 0, 750, 1500, and 3000 revolutions, and their physical-mechanical properties were analyzed. C. citriodora wood had a relatively high wood basic density (0.568 g/cm³), low lignin content (22.3%), and high holocellulose content (73.1%) compared with E. grandis x E. urophylla. The fibers of this species had 1.07 mm length, 16.1 μm width, and 66% wall fraction, which reflect its high basic density. For the same kappa number, C. citriodora and E. grandis x E. urophylla yields were similar – the main pulping highlight for this wood species is the low specific wood consumption – 2.93 m³/a.d. ton. C. citriodora pulp had a relatively lower kappa number after oxygen delignification and lower bleaching chemical demand than Eucalyptus pulp. C. citriodora pulp had a high specific volume and capillarity, and low water retention value. The physical properties of C. citriodora suggest that it might be suitable for use in tissue paper manufacturing.