Evaluation of the co-product pulp from Salix viminalis energy crops

Salix viminalis is among the species that are considered as promising for future energy crops in marginal lands throughout Canada. Whilst research conducted on Salix species is oriented, to a large extent, towards the hydrolytic production of sugars for fermentation, we have considered co-product fibre since it adds potential value to an integrated use of the biomass. In this study, extractives, lignin, hemicellulose, holocellulose and α-cellulose have been quantified using ASTM or TAPPI standard methods. Carbohydrates found in the hemicellulose were also quantified using HPLC. Hemicellulose comparison for one and three years old samples showed that the xylose content increases with age during this growth period. Kraft pulp has been produced at a bench scale (few kg range) using established pulping conditions. The pulp was tested following ATTPC standard methods. Pulp yields were of 29% and 34% for one and three years old samples respectively. The average fibre lengths were shorter for the younger samples, 0.35 mm, as compared with the older samples, 0.41 mm. Short fibres are not necessarily related to the species as much as to the fact that the samples used for the pulping were from young wood. When compared to industrial pulp, the basket willow pulp showed mechanical properties comparable to hardwood pulp which implies that this pulp could eventually be used in similar applications. Comparison with other energy crops shows advantages from the perspective of using this energy crop in Canada to co-produce pulp and, following suitable hydrolysis, sugars for fermentation to ethanol.