Fractionation of Pinus radiata by ethanol-based organosolv process

Abstract

The lignocellulosic materials are promising feedstock to produce biofuels and bioproducts in the biorefnery framework. However, a pretreatment step is required to disrupt lignin-carbohydrate complex. In this work, the fractionation of Pinus radiata wood into its main components, cellulose-rich delignifed solid, recovered lignin after precipitation, and solublein-black liquor hemicellulose, was studied. For this purpose, an organosolv process employing ethanol/water mixture as solvent in absence of a catalyst was carried out. The efects of operating conditions on delignifed solid were evaluated by using a 23 central composite experimental design, being the responses delignifed solid yield, delignifcation degree, hemicellulose content, and glucan content. The variables studied were temperature (170–200 °C), time (50–100 min), and ethanol concentration (40–60%). The increase of organosolv severity (temperature and time) and reduction of ethanol concentration favor the glucan enrichment of delignifed solid, due to lignin removal and hemicellulose solubilization. A glucan content of more than 66% is obtained by applying temperature higher than 195 °C and time longer than 90 min, when 40 wt% alcohol concentration is used. The liquid fraction obtained during the organosolv process (black liquors) was used to recover lignin and hemicellulosic fractions solubilized. Furthermore, hemicellulose and lignin content of delignifed solid was correlated with the thermal stability measured as T10%.