Organosolv pulping. VIII. Formic acid delignification of Pinus radiata D-Don

The aim of this study was to optimize the organosolv cooking system involvi ng formic acid as a cooking agent. The wood raw material used was Pinus rad iata D. Don sawdust and the cooks were performed on a small scale using 3 g o.d. sawdust in 100 mL of solvent. The effects of solvent ratio and cataly st on delignification were studied in order to optimize the process. A deli gnification yield of 65% was afforded with the sawdust, the cellulosic mate rial exhibiting 90.5% cellulose, 1.2% hemicellulose and 8.3% Klason lignin, catalyzed with 0.018% of HCl. Several delignification parameters were stud ied; among them, presoaking with NaHCO3 of Pinus radiata chips catalyzed wi th 0.018% HCl at 98% formic acid Br 3 h, gave a low reject value, Kappa num ber of around 60 and a 67% pulp yield. Celullose and Klason lignin of 79.5% and 11% were afforded, respectively. A preliminary pulp evaluation indicated that, at the same freeness of 42 de grees SR, a 25% less energy than in Kraft refining resulted. However, the f ormic pulp exhibited around 50% of the tear and burst indexes of those of K raft pulp.