Fractionation of Pinus radiata by ethanol-based organosolv process

The lignocellulosic materials are promising feedstock to produce biofuels and bioproducts in the biorefinery 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 delignified solid, recovered lignin after precipitation, and soluble-in-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 effects of operating conditions on delignified solid were evaluated by using a 2(3) central composite experimental design, being the responses delignified solid yield, delignification degree, hemicellulose content, and glucan content. The variables studied were temperature (170-200 degrees 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 delignified solid, due to lignin removal and hemicellulose solubilization. A glucan content of more than 66% is obtained by applying temperature higher than 195 degrees 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 delignified solid was correlated with the thermal stability measured as T-10%.

Automated summary

Lignocellulosic materials have great potential as feedstock for biofuel and bioproduct production. This study focused on the fractionation of Pinus radiata wood using an organosolv process. The effects of temperature, time, and ethanol concentration on the yield, degree of delignification, hemicellulose content, and glucan content of the delignified solid were evaluated. Increasing severity of the organosolv process and reducing ethanol concentration resulted in higher glucan enrichment in the delignified solid. The liquid fraction obtained during the process was used to recover lignin and hemicellulosic fractions. The hemicellulose and lignin content of the delignified solid were correlated with thermal stability measurements.