Formic acid/acetone-organosolv pulping of white-rotted Pinus radiata softwood

Organosolv pulping of fungally pretreated samples of Pinus radiata was eval uated. A screening study using five white-rot fungi indicated that Ceripori opsis subvermisopora and Punctularia artropurpurascens were the most select ive ones for lignin degradation. These fungi were further cultured in biore actors containing 2.5 kg of wood chips. Fungally-pretreated samples were de lignified by formic acid/acetone (7:3) at 150 degreesC. Pulping kinetics an d strength properties of the resulting unbleached pulps were evaluated. Del ignification rates and xylan solubilization rates were higher for the decay ed samples than for the undecayed control, except for the sample biotreated with P artropurpurascens for 30 days. C subvermispora proved appropriate f or treating the wood samples before organosolv pulping, since pretreatment with this fungus resulted in faster wood delignification and pulps with low er residual lignin. Increases in tensile index ranging from 3% to 22% were observed for most pulps prepared fi om biotreated samples, independently bo th of the fungal species used in the pretreatment and of the extent of the wood biodegradation expressed as wood weight loss. However, tear and burst indexes and brightness were lower than or similar to those of pulps prepare d from the undecayed control. (C) 2000 Society of Chemical Industry.