Up to now numerous wood treatments have been conducted mostly in the form of pre-hydrolysis of wood, focusing on hemicelluloses pre-extraction for co-production of pulp and chemicals. Our objective in this research was to investigate the effect of hot-water and green liquor pre-extraction of wheat straw on cooking process and papermaking properties of soda-AQ pulp. Wheat straw chips were treated with pure water and green liquor at 140 and 150 °C, respectively, to obtain 10 and 15% pre-extraction weight losses in both extraction methods. Cooking pre-extracted straw required less H-factor to get the target kappa number of about 20 and less PFI mill refining revolutions. The strength indices of hot-water pre-extracted pulps at both levels of pre-extracted weight losses, and of green liquor pre-extracted pulp only at 10%, were comparable to those of control pulp, except for tear index.
Wheat straw; Pre-extraction; Green liquor; Soda-AQ pulping