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The objective of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pre-treated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pre-treated material. Glucose yields after the enzymatic hydrolysis of pre-treated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles were deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR imaging; these microscopic techniques show changes in the physical and chemical characteristics of pre-treated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pre-treated lignocellulose.
Eduardo Troncoso-Ortega; Rosario Castillo; Pablo Reyes-Contreras; Patricia Castaño-Rivera; Regis Teixeira Mendonça; Nicolás Schiappacasse; Carolina Parra. Effects on Lignin Redistribution in Eucalyptus globulus Fibres Pre-Treated by Steam Explosion: A Microscale Study to Cellulose Accessibility. Biomolecules 2021, 11, 507 .
AMA StyleEduardo Troncoso-Ortega, Rosario Castillo, Pablo Reyes-Contreras, Patricia Castaño-Rivera, Regis Teixeira Mendonça, Nicolás Schiappacasse, Carolina Parra. Effects on Lignin Redistribution in Eucalyptus globulus Fibres Pre-Treated by Steam Explosion: A Microscale Study to Cellulose Accessibility. Biomolecules. 2021; 11 (4):507.
Chicago/Turabian StyleEduardo Troncoso-Ortega; Rosario Castillo; Pablo Reyes-Contreras; Patricia Castaño-Rivera; Regis Teixeira Mendonça; Nicolás Schiappacasse; Carolina Parra. 2021. "Effects on Lignin Redistribution in Eucalyptus globulus Fibres Pre-Treated by Steam Explosion: A Microscale Study to Cellulose Accessibility." Biomolecules 11, no. 4: 507.
Lignin is one of the wood and plant cell wall components that is available in large quantities in nature. Its polyphenolic chemical structure has been of interest for valorization and industrial application studies. Lignin can be obtained from wood by various delignification chemical processes, which give it a structure and specific properties that will depend on the plant species. Due to the versatility and chemical diversity of lignin, the chemical industry has focused on its use as a viable alternative of renewable raw material for the synthesis of new and sustainable biomaterials. However, its structure is complex and difficult to characterize, presenting some obstacles to be integrated into mixtures for the development of polymers, fibers, and other materials. The objective of this review is to present a background of the structure, biosynthesis, and the main mechanisms of lignin recovery from chemical processes (sulfite and kraft) and sulfur-free processes (organosolv) and describe the different forms of integration of this biopolymer in the synthesis of sustainable materials. Among these applications are phenolic adhesive resins, formaldehyde-free resins, epoxy resins, polyurethane foams, carbon fibers, hydrogels, and 3D printed composites.
Francisco Vásquez-Garay; Isabel Carrillo-Varela; Claudia Vidal; Pablo Reyes-Contreras; Mirko Faccini; Regis Teixeira Mendonça. A Review on the Lignin Biopolymer and Its Integration in the Elaboration of Sustainable Materials. Sustainability 2021, 13, 2697 .
AMA StyleFrancisco Vásquez-Garay, Isabel Carrillo-Varela, Claudia Vidal, Pablo Reyes-Contreras, Mirko Faccini, Regis Teixeira Mendonça. A Review on the Lignin Biopolymer and Its Integration in the Elaboration of Sustainable Materials. Sustainability. 2021; 13 (5):2697.
Chicago/Turabian StyleFrancisco Vásquez-Garay; Isabel Carrillo-Varela; Claudia Vidal; Pablo Reyes-Contreras; Mirko Faccini; Regis Teixeira Mendonça. 2021. "A Review on the Lignin Biopolymer and Its Integration in the Elaboration of Sustainable Materials." Sustainability 13, no. 5: 2697.
Low-density polyethylene composites containing different sizes of calcium oxide (CaO) nanoparticles were obtained by melt mixing. The CaO nanoparticles were synthesized by either the sol-gel or sonication methods, obtaining two different sizes: ca. 55 nm and 25 nm. These nanoparticles were used either as-synthesized or were modified organically on the surface with oleic acid (Mod-CaO), at concentrations of 3, 5, and 10 wt% in the polymer. The Mod-CaO nanoparticles of 25 nm can act as nucleating agents, increasing the polymer’s crystallinity. The Young’s Modulus increased with the Mod-CaO nanoparticles, rendering higher reinforcement effects with an increase as high as 36%. The reduction in Escherichia coli bacteria in the nanocomposites increased with the amount of CaO nanoparticles, the size reduction, and the surface modification. The highest antimicrobial behavior was found in the composites with a Mod-CaO of 25 nm, presenting a reduction of 99.99%. This strong antimicrobial effect can be associated with the release of the Ca2+ from the composites, as studied for the composite with 10 wt% nanoparticles. The ion release was dependent on the size of the nanoparticles and their surface modification. These findings show that CaO nanoparticles are an excellent alternative as an antimicrobial filler in polymer nanocomposites to be applied for food packaging or medical devices.
Cristián Silva; Felipe Bobillier; Daniel Canales; Francesca Antonella Sepúlveda; Alejandro Cament; Nicolás Amigo; Lina M. Rivas; María T. Ulloa; Pablo Reyes-Contreras; J. Andrés Ortiz; Tatiana Gómez; Carlos Loyo; Paula A. Zapata. Mechanical and Antimicrobial Polyethylene Composites with CaO Nanoparticles. Polymers 2020, 12, 2132 .
AMA StyleCristián Silva, Felipe Bobillier, Daniel Canales, Francesca Antonella Sepúlveda, Alejandro Cament, Nicolás Amigo, Lina M. Rivas, María T. Ulloa, Pablo Reyes-Contreras, J. Andrés Ortiz, Tatiana Gómez, Carlos Loyo, Paula A. Zapata. Mechanical and Antimicrobial Polyethylene Composites with CaO Nanoparticles. Polymers. 2020; 12 (9):2132.
Chicago/Turabian StyleCristián Silva; Felipe Bobillier; Daniel Canales; Francesca Antonella Sepúlveda; Alejandro Cament; Nicolás Amigo; Lina M. Rivas; María T. Ulloa; Pablo Reyes-Contreras; J. Andrés Ortiz; Tatiana Gómez; Carlos Loyo; Paula A. Zapata. 2020. "Mechanical and Antimicrobial Polyethylene Composites with CaO Nanoparticles." Polymers 12, no. 9: 2132.
Kraft pulp cellulose was hydrolyzed using sulfuric acid, under different thermophysical conditions of temperature, time, pulp concentration, and sonication time. The experimental design revealed the effect of these conditions and their interaction on the hydrolysis yield obtained. In addition, the top five cellulose nanocrystals (CNCs) yields from this experiment design were analyzed. The results obtained indicated that CNCs possess a morphology that can be described as individualized rod particles, with average diameters less than 50 nm and different size distribution. In the analysis of CNCs features, significant Pearson correlations were established between the crystallinity of the CNC, CNC yield, and interplanar crystallites distance (Δd/d). The thermogravimetric (DTG) profiles exhibited two CNCs degradation stages, where the second stage CNCs degradation showed a significative correlation with CNC sulfur content. In our analysis, the crystallographic parameters exhibited a correlation with the mechanical behavior of the CNC, since the potential variation between the distances of the crystalline planes is related to the stress and deformation present in the crystallites of CNCs. This study provides new knowledge regarding CNCs, further enhancing information for CNC-based industries and the processability of CNCs for the development of new materials.
María Aguayo; Arturo Fernández-Pérez; Claudia Oviedo; Guillermo Reyes; Pablo Reyes-Contreras. Relationship between Structural Characteristics of Cellulose Nanocrystals Obtained from Kraft Pulp. Nanomaterials 2020, 10, 1775 .
AMA StyleMaría Aguayo, Arturo Fernández-Pérez, Claudia Oviedo, Guillermo Reyes, Pablo Reyes-Contreras. Relationship between Structural Characteristics of Cellulose Nanocrystals Obtained from Kraft Pulp. Nanomaterials. 2020; 10 (9):1775.
Chicago/Turabian StyleMaría Aguayo; Arturo Fernández-Pérez; Claudia Oviedo; Guillermo Reyes; Pablo Reyes-Contreras. 2020. "Relationship between Structural Characteristics of Cellulose Nanocrystals Obtained from Kraft Pulp." Nanomaterials 10, no. 9: 1775.
Effective antimicrobial polymeric nanocomposites were prepared with low density polyethylene (LDPE) and zinc oxide nanoparticles by melt compounding. These nanoparticles (∼17 nm) obtained by the sol–gel method, were used both as-synthesized and modified organically with oleic acid (Mod-ZnO). Young's modulus increased ∼15 and 18% for LDPE/ZnO and LDPE/Mod-ZnO, respectively, compared to neat LDPE. When these composites were irradiated with white light, they showed an increase with nanoparticle incorporation, and the antimicrobial properties against E. coli were ∼96–99%. The release of the Zn cations was related to the antimicrobial properties. These nanocomposites are attractive for use as food packaging without external irradiation.
Karina Rojas; Daniel Canales; Nicolas Amigo; Lissette Montoille; Alejandro Cament; Lina M. Rivas; Oscar Gil-Castell; Pablo Reyes-Contreras; Maria Teresa Ulloa; A. Ribes-Greus; Paula A. Zapata. Effective antimicrobial materials based on low-density polyethylene (LDPE) with zinc oxide (ZnO) nanoparticles. Composites Part B: Engineering 2019, 172, 173 -178.
AMA StyleKarina Rojas, Daniel Canales, Nicolas Amigo, Lissette Montoille, Alejandro Cament, Lina M. Rivas, Oscar Gil-Castell, Pablo Reyes-Contreras, Maria Teresa Ulloa, A. Ribes-Greus, Paula A. Zapata. Effective antimicrobial materials based on low-density polyethylene (LDPE) with zinc oxide (ZnO) nanoparticles. Composites Part B: Engineering. 2019; 172 ():173-178.
Chicago/Turabian StyleKarina Rojas; Daniel Canales; Nicolas Amigo; Lissette Montoille; Alejandro Cament; Lina M. Rivas; Oscar Gil-Castell; Pablo Reyes-Contreras; Maria Teresa Ulloa; A. Ribes-Greus; Paula A. Zapata. 2019. "Effective antimicrobial materials based on low-density polyethylene (LDPE) with zinc oxide (ZnO) nanoparticles." Composites Part B: Engineering 172, no. : 173-178.
The objective of this research was to study the chemical and nanomechanical characteristics of native woods grown in southern Chile region. The species analysed were Drimys winteri, Laureliopsis philippiana, Aextoxicon puctatum, Nothofagus alpina, Nothofagus dombeyi, Laurelia sempervirens, Austrocedrus chilensis and Fitzroya cupressoides. The samples were collected from the regions of Biobío (37° S, 73° W), Araucanía (37° S, 71° W) and Los Lagos (40° S, 73° W). Chemical analysis reported that glucan content of native woods was between 39% and 44% and lignin content between 28% and 35%. The nanomechanical properties analysed in the secondary cell wall (S2 layer) and middle lamella (ML) were elastic modulus (E), hardness (H) and ductility ratio (E/H). Values for ES2 were between 12.0 and 15.4 GPa and for EML between 4.3 and 6.6 GPa. Hardness values were similar in ML and S2 (≈0.3 GPa). The compilation of results showed high correlations between ES2 and carbohydrate content (r = 0.80), between ES2 and hemicellulose content (r = 0.89), and between HS2 and lignin content (r = 0.88).
María Graciela Aguayo; William Gacitúa; Paulina Valenzuela; Regis Teixeira Mendonça; Pablo Reyes-Contreras. Chemical characteristics of woods from several Chilean native forest species and their relationship with nanomechanical cell properties. Southern Forests: a Journal of Forest Science 2017, 80, 293 -300.
AMA StyleMaría Graciela Aguayo, William Gacitúa, Paulina Valenzuela, Regis Teixeira Mendonça, Pablo Reyes-Contreras. Chemical characteristics of woods from several Chilean native forest species and their relationship with nanomechanical cell properties. Southern Forests: a Journal of Forest Science. 2017; 80 (4):293-300.
Chicago/Turabian StyleMaría Graciela Aguayo; William Gacitúa; Paulina Valenzuela; Regis Teixeira Mendonça; Pablo Reyes-Contreras. 2017. "Chemical characteristics of woods from several Chilean native forest species and their relationship with nanomechanical cell properties." Southern Forests: a Journal of Forest Science 80, no. 4: 293-300.
In order to understand the relation between chemical composition, microscopic structure and enzymatic digestibility, different Eucalyptus globulus wood pretreated samples were examined. Pretreated materials obtained by steam explosion and autohydrolysis were compared with those obtained by organosolv and kraft processes. Chemical analyses of pretreated materials showed a decrease in the content of xylans, except in the kraft pulp. FT-IR spectra showed that the residual lignin in autohydrolysis pulp had experienced greater changes compared to those in steam explosion and organosolv pulps, whereas minor changes in lignin kraft pulp were observed. The fiber morphology indicated that autohydrolysis pretreatment was the most aggressive treatment. Reduction in the content of lignin and its redistribution on the fiber wall were confirmed through confocal laser microscopy. The formation of discrete lignin droplets deposited on the surface of the fibers was observed in all pretreatments, with a higher frequency in organosolv followed by steam explosion. A significant increase in enzymatic accessibility was achieved in organosolv, autohydrolysis and steam explosion pulps, due to xylans removal combined with lignin redistribution. Homogeneous lignin distribution and higher xylan content may be related to the low enzymatic hydrolysis efficiency in kraft pulp.
Eduardo Troncoso; Rosario Castillo; Roberto Valenzuela; Pablo Reyes; Juanita Freer; Marcela Norambuena; Jaime Rodríguez; Carolina Parra. CHEMICAL AND MICROSTRUCTURAL CHANGES IN EUCALYPTUS GLOBULUS FIBERS SUBJECTED TO FOUR DIFFERENT PRETREATMENTS AND THEIR INFLUENCE ON THE ENZYMATIC HYDROLYSIS. Journal of the Chilean Chemical Society 2017, 62, 3442 -3446.
AMA StyleEduardo Troncoso, Rosario Castillo, Roberto Valenzuela, Pablo Reyes, Juanita Freer, Marcela Norambuena, Jaime Rodríguez, Carolina Parra. CHEMICAL AND MICROSTRUCTURAL CHANGES IN EUCALYPTUS GLOBULUS FIBERS SUBJECTED TO FOUR DIFFERENT PRETREATMENTS AND THEIR INFLUENCE ON THE ENZYMATIC HYDROLYSIS. Journal of the Chilean Chemical Society. 2017; 62 (2):3442-3446.
Chicago/Turabian StyleEduardo Troncoso; Rosario Castillo; Roberto Valenzuela; Pablo Reyes; Juanita Freer; Marcela Norambuena; Jaime Rodríguez; Carolina Parra. 2017. "CHEMICAL AND MICROSTRUCTURAL CHANGES IN EUCALYPTUS GLOBULUS FIBERS SUBJECTED TO FOUR DIFFERENT PRETREATMENTS AND THEIR INFLUENCE ON THE ENZYMATIC HYDROLYSIS." Journal of the Chilean Chemical Society 62, no. 2: 3442-3446.
The combination of hemicellulose pre-hydrolysis by dilute acid or steam-explosion followed by kraft pulping was one approach evaluated in this work to generate pulps from radiata pine wood chips amenable to saccharification by enzymatic hydrolysis. Dilute acid (combined severity factor, CS = 1.67) and steam explosion (severity factor, log Ro = 4.09) treatments were able to solubilize approximately 53% and 63% of the original hemicelluloses content in wood, respectively. Extracted wood chips were subjected to kraft cooking (170 °C, 16-18% active alkali, 30% sulfidity and 1200 H-factor) to produce pulps that were further saccharified by cellulases. Lignin removal increased with increasing active alkali, affording delignification levels 28% for dilute acid and 68% for steam explosion extraction pretreatment pulps. Enzymatic digestibility of P. radiata pulps were low, and only samples pretreated by steam explosion reached glucan-to-glucose conversion near to 75%; this treatment was 31% and 37% higher than that obtained with wood chips that were pretreated by dilute acid extraction.
Pablo Reyes; Nicole Márquez; Eduardo Troncoso; Carolina Parra; Regis Teixeira Mendonça; Jaime Rodriguez. Evaluation of Combined Dilute Acid-Kraft and Steam Explosion-Kraft Processes as Pretreatment for Enzymatic Hydrolysis of Pinus radiata Wood Chips. BioResources 2015, 11, 1 .
AMA StylePablo Reyes, Nicole Márquez, Eduardo Troncoso, Carolina Parra, Regis Teixeira Mendonça, Jaime Rodriguez. Evaluation of Combined Dilute Acid-Kraft and Steam Explosion-Kraft Processes as Pretreatment for Enzymatic Hydrolysis of Pinus radiata Wood Chips. BioResources. 2015; 11 (1):1.
Chicago/Turabian StylePablo Reyes; Nicole Márquez; Eduardo Troncoso; Carolina Parra; Regis Teixeira Mendonça; Jaime Rodriguez. 2015. "Evaluation of Combined Dilute Acid-Kraft and Steam Explosion-Kraft Processes as Pretreatment for Enzymatic Hydrolysis of Pinus radiata Wood Chips." BioResources 11, no. 1: 1.
Conditions to increase phenolic hydroxyl groups (OH-Phe) in organosolv lignin using alkaline catalysts (NaOH and KOH) were optimized with the purpose of increasing the reactivity of lignin and to evaluate the effect on the structure of the newly generated compounds as a result of the base-catalyzed depolymerization (BCD). The lignin-derived compounds could be used for the synthesis of bio-based polymers and nanomaterials. The maximal yield of OH-Phe reached values of 5270 and 3970 μmol per gram of lignin when NaOH (8.6%, 173 °C, and 33 min) and KOH (11.7%, 174 °C, and 58 min), defined as optimal conditions for BCD, were used, respectively, while for the control lignin, OH-Phe was 2830 μmol per gram of lignin. The molecular weight (Mw) and glass transition temperature (Tg) for lignin-NaOH were lower than those of lignin-KOH and lignin-control. Both lignin derivatives had greater thermal stability at high temperatures than lignin-control. In conclusion, the results showed higher modifications in the structure of lignin as a result of the oxidation process, primarily by cleavage of the β-O-4 ether bond and variations in thermochemical properties when NaOH is used as alkaline catalyst.
Marcela Norambuena; Claudia Vidal; Lissette Carrasco; Pablo Reyes; Carolina Parra; David Contreras; Regis Teixeira Mendonça. Optimization of Experimental Variables to Modify Lignin from Eucalyptus globulus under Alkaline Catalysis. BioResources 2015, 11, 1 .
AMA StyleMarcela Norambuena, Claudia Vidal, Lissette Carrasco, Pablo Reyes, Carolina Parra, David Contreras, Regis Teixeira Mendonça. Optimization of Experimental Variables to Modify Lignin from Eucalyptus globulus under Alkaline Catalysis. BioResources. 2015; 11 (1):1.
Chicago/Turabian StyleMarcela Norambuena; Claudia Vidal; Lissette Carrasco; Pablo Reyes; Carolina Parra; David Contreras; Regis Teixeira Mendonça. 2015. "Optimization of Experimental Variables to Modify Lignin from Eucalyptus globulus under Alkaline Catalysis." BioResources 11, no. 1: 1.
Extraction of hemicelluloses prior to pulping and conversion of the extracted hemicelluloses to other bioproducts could provide additional revenue to traditional pulp and paper industries. The effect of hemicelluloses pre-extraction with a hydrothermal (HT) process on Pinus radiata chemimechanical pulp (CMP) properties was investigated in this study. The HT extraction resulted in a release of 7% to 58% of the initial amount of hemicelluloses from the wood. The extraction yield increased with temperature and extraction time. This hemicellulosic fraction was in the form of low molar mass oligomers with molecular weights varying from 1.5 to 100 kDa. Compared with the control (unextracted) CMP pulp, the HT pre-extraction significantly reduced the refining energy to obtain a given fibrillation degree (freeness). The pulp yield with the HT/CMP process was in the range of 56% to 75%. Fiber properties of the pulps from pre-extracted wood, such as fiber length, were reduced, while increases in fiber width, fines content, fiber coarseness, and kink index were observed in comparison with the control pulps. The strength properties of CMP pulps decreased with increasing amounts of hemicellulose removal during the stage prior to pulping.
Pablo Reyes; Miguel Pereira; Regis Teixeira Mendonça. Effect of Partial Pre-Extraction of Hemicelluloses on the Properties of Pinus radiata Chemimechanical Pulps. BioResources 2015, 10, 1 .
AMA StylePablo Reyes, Miguel Pereira, Regis Teixeira Mendonça. Effect of Partial Pre-Extraction of Hemicelluloses on the Properties of Pinus radiata Chemimechanical Pulps. BioResources. 2015; 10 (4):1.
Chicago/Turabian StylePablo Reyes; Miguel Pereira; Regis Teixeira Mendonça. 2015. "Effect of Partial Pre-Extraction of Hemicelluloses on the Properties of Pinus radiata Chemimechanical Pulps." BioResources 10, no. 4: 1.
Pinus radiata D. Don wood chips were submitted to a hydrothermal (HT) process, which is a pretreatment with pressurized water at P-factors of 20 (E1) and 1200 (E2), leading to 27% and 56% of hemicellulose removal, respectively. The residual wood chips were pulped by the chemithermomechanical (CTMP) and kraft processes. The pulp yield in the HT/CTMP process was in the range of 56–75%. The cellulose yields were not affected by the HT pretreatment, whereas the solubilization of hemicelluloses and lignin was intensified. The HT process provided energy savings in the refining of CTMP pulps, and the E1/CTMP pulp had a similar tensile and increased tear strength as the control wood. For kraft pulping, the HT wood chips demanded more active alkali (AA) to achieve a κ number (KN) of 30, and consequently, a decrease in pulp yield was observed (47.2% yield in the control and 44.4% and 37.8% in the E1 and E2 pulps, respectively). The fiber length decreased in the E1 and E2 kraft pulps compared with their control samples. In the E1 pulps, the tensile, tear, and burst indexes decreased by 10%, 25%, and 30%, respectively. Considering the low hemicellulose content and pulp viscosity in the range of 800–900 ml g-1, the mild HT process of P. radiata would be better suited for preparing cellulose-rich materials instead of paper-grade pulps under the biorefinery concept.
Pablo Reyes-Contreras; Andre Ferraz; Miguel Pereira; Jaime Rodríguez; Regis Teixeira Mendonça. Chemithermomechanical and kraft pulping of Pinus radiata wood chips after the hydrothermal extraction of hemicelluloses. Holzforschung 2015, 69, 33 -40.
AMA StylePablo Reyes-Contreras, Andre Ferraz, Miguel Pereira, Jaime Rodríguez, Regis Teixeira Mendonça. Chemithermomechanical and kraft pulping of Pinus radiata wood chips after the hydrothermal extraction of hemicelluloses. Holzforschung. 2015; 69 (1):33-40.
Chicago/Turabian StylePablo Reyes-Contreras; Andre Ferraz; Miguel Pereira; Jaime Rodríguez; Regis Teixeira Mendonça. 2015. "Chemithermomechanical and kraft pulping of Pinus radiata wood chips after the hydrothermal extraction of hemicelluloses." Holzforschung 69, no. 1: 33-40.
Hemicelluloses from Pinus radiata wood chips were extracted using different conditions of temperature, time and initial pH of water (120 to 170°C, 30 to 120 min and pH 2 to 12, respectively). Results showed that hemicelluloses represented 26% of wood dry weight and, from this amount, hexoses are responsible for 64% of its composition. The analysis of extraction results showed that pH has a low effect in disassembling hemicelluloses from wood, and that time and temperature of reaction were the most important parameters. Maximal amount of hemicellulose extracted in the most severe conditions tested was between 12-16% (on wood basis). In these conditions approximately 40-50% of the hemicellulose in wood was solubilized. As observed by SEC analysis, the recovered hemicellulosic fractions were in the form of low molar mass oligomers with Mw varying from 3720 to 54300 g/mol. The FT-IR spectra show peak multiplicity between 1120 and 1000 cm-1 that is a typical characteristic of carbohydrates and only alkaline-extracted hemicelluloses showed the presence of lignin with a characteristic peak at 1509 cm-1.
Pablo Reyes-Contreras; Regis Teixeira Mendonça; Jaime Rodríguez; Pedro Fardim; Beatriz Vega. CHARACTERIZATION OF THE HEMICELLULOSIC FRACTION OBTAINED AFTER PRE-HYDROLYSIS OF PINUS RADIATA WOOD CHIPS WITH HOT-WATER AT DIFFERENT INITIAL PH. Journal of the Chilean Chemical Society 2013, 58, 1614 -1618.
AMA StylePablo Reyes-Contreras, Regis Teixeira Mendonça, Jaime Rodríguez, Pedro Fardim, Beatriz Vega. CHARACTERIZATION OF THE HEMICELLULOSIC FRACTION OBTAINED AFTER PRE-HYDROLYSIS OF PINUS RADIATA WOOD CHIPS WITH HOT-WATER AT DIFFERENT INITIAL PH. Journal of the Chilean Chemical Society. 2013; 58 (1):1614-1618.
Chicago/Turabian StylePablo Reyes-Contreras; Regis Teixeira Mendonça; Jaime Rodríguez; Pedro Fardim; Beatriz Vega. 2013. "CHARACTERIZATION OF THE HEMICELLULOSIC FRACTION OBTAINED AFTER PRE-HYDROLYSIS OF PINUS RADIATA WOOD CHIPS WITH HOT-WATER AT DIFFERENT INITIAL PH." Journal of the Chilean Chemical Society 58, no. 1: 1614-1618.
As galactoglucomananas são as principais frações de hemiceluloses presentes nas madeiras moles e contêm, principalmente, as hexoses galactose, glicose e manose. O isolamento eficiente e seletivo dessas hemiceluloses é um obstáculo crítico a superar para sua utilização. Os objetivos deste trabalho foram extrair e caracterizar soluções aquosas ácidas e neutras de hemiceluloses de cavacos de madeira de Pinus radiata, bem como avaliar sua viabilidade para a produção de bioetanol. As hemiceluloses em P. radiata representam 26 g/100 g de madeira (base seca), e as hexoses são responsáveis por aproximadamente 64% dessa quantidade. De acordo com as diferentes condições de extração, cerca de 50% da fração hemicelulósica foi solubilizada e recuperada depois de uma precipitação com etanol. As frações recuperadas de hemiceluloses estavam na forma de oligômeros com peso molecular médio (Mw) variando entre 4x10³ e 4x10(5) g/mol. Os oligômeros hemicelulósicos foram hidrolisados com ácido sulfúrico diluído e os hidrolisados concentrados até aproximadamente 70 g/L hexosas e fermentados pela levedura Saccharomyces cerevisiae. Os resultados de fermentação indicaram que os açúcares obtidos dos extratos ácidos e neutros foram fermentados com rendimentos máximos de etanol de 63% e 54% (22 g/L e 19 g/L), respectivamente. A conversão de hemiceluloses da madeira em etanol é viável, porém seu baixo rendimento faz que o processo não seja economicamente atrativo, razão por que melhorias no processo ou usos alternativos das hemiceluloses devem ser avaliados.
Pablo Reyes; Regis Teixeira Mendonça; María Graciela Aguayo; Jaime Rodríguez; Beatriz Vega; Pedro Fardim. Extração e caracterização de hemiceluloses de Pinus radiata e sua viabilidade para a produção de bioetanol. Revista Árvore 2013, 37, 175 -180.
AMA StylePablo Reyes, Regis Teixeira Mendonça, María Graciela Aguayo, Jaime Rodríguez, Beatriz Vega, Pedro Fardim. Extração e caracterização de hemiceluloses de Pinus radiata e sua viabilidade para a produção de bioetanol. Revista Árvore. 2013; 37 (1):175-180.
Chicago/Turabian StylePablo Reyes; Regis Teixeira Mendonça; María Graciela Aguayo; Jaime Rodríguez; Beatriz Vega; Pedro Fardim. 2013. "Extração e caracterização de hemiceluloses de Pinus radiata e sua viabilidade para a produção de bioetanol." Revista Árvore 37, no. 1: 175-180.
Wood chips of Pinus radiata softwood were biotreated with the brown rot fungus (BRF) Gloeophyllum trabeum for periods from 4 and 12 weeks. Biodegradation by BRF leads to an increase in cellulose depolymerization with increasing incubation time. As a result, the intrinsic viscosity of holocellulose decreased from 1,487 cm3/g in control samples to 783 and 600 cm3/g in 4- and 12-week decayed wood chips, respectively. Wood weight and glucan losses varied from 6 to 14% and 9 to 21%, respectively. Undecayed and 4-week decayed wood chips were delignified by alkaline (NaOH solution) or organosolv (ethanol/water) processes to produced cellulosic pulps. For both process, pulp yield was 5–10% lower for decayed samples than for control pulps. However, organosolv bio-pulps presented low residual lignin amount and high glucan retention. Chemical pulps and milled wood from undecayed and 4-week decayed wood chips were pre-saccharified with cellulases for 24 h at 50°C followed by simultaneous saccharification and fermentation (SSF) with the yeast Saccharomyces cerevisiae IR2-9a at 40°C for 96 h for bioethanol production. Considering glucan losses during wood decay and conversion yields from chemical pulping and SSF processes, no gains in ethanol production were obtained from the combination of BRF with alkaline delignification; however, the combination of BRF and organosolv processes resulted in a calculated production of 210 mL ethanol/kg wood or 72% of the maximum theoretically possible from that pretreatment, which was the best result obtained in the present study.
Antonella Fissore; Lissete Carrasco; Pablo Reyes-Contreras; Jaime Rodríguez; Juanita Freer; Regis Teixeira Mendonça. Evaluation of a combined brown rot decay–chemical delignification process as a pretreatment for bioethanol production from Pinus radiata wood chips. Journal of Industrial Microbiology and Biotechnology 2010, 37, 893 -900.
AMA StyleAntonella Fissore, Lissete Carrasco, Pablo Reyes-Contreras, Jaime Rodríguez, Juanita Freer, Regis Teixeira Mendonça. Evaluation of a combined brown rot decay–chemical delignification process as a pretreatment for bioethanol production from Pinus radiata wood chips. Journal of Industrial Microbiology and Biotechnology. 2010; 37 (9):893-900.
Chicago/Turabian StyleAntonella Fissore; Lissete Carrasco; Pablo Reyes-Contreras; Jaime Rodríguez; Juanita Freer; Regis Teixeira Mendonça. 2010. "Evaluation of a combined brown rot decay–chemical delignification process as a pretreatment for bioethanol production from Pinus radiata wood chips." Journal of Industrial Microbiology and Biotechnology 37, no. 9: 893-900.