Analysis of pulp and lignin extracted with formic acid-acetone mixture from Pinus radiata and Eucalyptus globulus woods

The aim of this work is the characterization of lignins and pulps obtained from Pinus radiata and Eucalyptus globulus woods by organosolv pulping usin g formic acidi acetone mixture as cooking agent. The samples were character ized by Fourier transform infrared spectroscopy (FTIR), high performance si ze exclusion chromatography (HPSEC) and chemical techniques. The lignins we re precipitated by water from the black liquors of the wood pulping with fo rmic acid/acetone (7:3 v/v), at temperatures of 154 degrees C and 165 degre es C for eucalyptus and pine, respectively. The FTIR spectra of the pulps i ndicated an effective delignification which was corroborated by the kappa n umbers. The IR spectra of the lignins showed that they are highly condensed , with condensation indeces higher in pine lignins than in those extracted from eucalyptus, which increased as the pulping temperature was increased. The strong absorbance at 1720 cm(-1) in the spectra of the lignins indicate d the presence of saponifiable ester groups, possibly formate. High polydis persity of the samples of lignins was observed, which was lower in the euca lyptus than in the pine lignins. The molecular masses of the formic acid-ac etone lignins were relatively higher than those found for other organosolv lignins.