Suchergebnisse

The aim of this work was the evaluation of lime pretreatment combined or not with previous step of autohydrolysis for oat straw valorization. Under selected conditions of lime pretreatment, 96% of glucan and 77% of xylan were recovered and 42% of delignification was achieved. Xylose fermentation to ethanol by metabolic engineered Saccharomyces cerevisiae (MEC1133) strain improved the ethanol production by 22% achieving 41 g/L. Alternatively, first step of autohydrolysis (S0=4.22) allowed a high oligosaccharides recovery (68%) and subsequent lime pretreatment attained a 57% of delignification and 99% of glucan to glucose conversion. Oat straw processed by autohydrolysis and lime pretreatment reached the maximal ethanol concentration (50 g/L). Both strategies led to oat straw valorization into bioethanol, oligosaccharides and lignin indicating that these pretreatments are adequate as a first stage within an oat straw biorefinery. ; The authors thank the financial support from the Strategic Project of UID/BIO/04469/2013 CEB Unit (Funding agency for Science and Technology, FCT, Portugal) and for the Project CTQ2012-30855 of the Spanish "Ministry of Science and Innovation", partially funded by the FEDER program of the European Union. A Romani thanks her post-doctoral grant funded by Xunta of Galicia (Plan I2C, ...

In this work, we determined the properties of cellulose pulp and paper from six different lignocellulosic materials [Eucalyptus globulus, Arundo donax, Leucaena diversifolia, Paulownia fortunei, sunflower stalks and Chamaecytisus proliferus (tagasaste)], as well as the calorific value and chemical composition of their autohydrolysis liquor, with a view to assessing their potential for the obtainment of energy, sugars and other chemical products. An integral fractionation method based on autohydrolysis and organosolv delignification was used for this purpose. Leucaena diversifolia; P. fortunei; a Paulownia "trihybrid" consisting of elongata, tormentosa and fortunei varieties; sunflower stalks; and C. proliferus exhibited holocellulose, glucan, xylan and acetyl group contents similar to, or higher than, those of E. globulus, A. donax and various other lignocellulosic materials. The amounts of oligomers extracted from C. proliferus, P. fortunei, L. diversifolia and sunflower stalks at the highest temperatures studied exceeded those provided by eucalyptus. Sequential autohydroysis and organosolv delignification of L. diversifolia and C. proliferus provided cellulose pulp with an acceptable kappa number and paper sheets with good strength-related properties. Paulownia fortunei was the most interesting raw material among those tested; in fact, it provided ethanol pulp with a lignin content of 3.7 –15.3% and a kappa number of 40.5–74.1 after autohydrolysis at 190 ºC, and paper with a tensile index of 17.0–28.9 kN m/kg. These properties are similar to those of pulp and paper from eucalyptus wood. In addition, P. fortunei exhibited the highest calorific value among the studied materials (4683.8 cal/g). ; The authors gratefully acknowledge funding of their Project CTQ2006-10329/PPQ by ENCE, S.A. (San Juan del Puerto factory, Huelva, Spain) and CICYT-FEDER (Science and Technology Inter-Ministry Commission, Spanish Government - European Regional Development Fund), and additional funding within the framework of the Ramon y Cajal and Juan de la Cierva programmes (Spain's Ministry of Education and Science).