Thermoplastic Films Based on Polyelectrolyte Complexes of Arabino Glucurono-Xylan and Polyethylenimine

This work investigates film formation using polyelectrolyte complexes (PECs) of xylan and polyethylenimine (PEI). Different xylan/PEI mass ratios (from 50/50 to 90/10) and pH values (5.0 and 7.0) are analyzed and both parameters have an effect on complex size and film properties. Furthermore, the mass ratio corresponding to the neutralization charge depends on pH. When xylan/PEI mass ratios are near the neutralization charge ratio, a coacervation process is observed. In this case, separation between the coacervate and the supernatant dilute phase is possible. In the supernatant, both concentrations, xylan and PEI, depend on pH. The complex suspensions are used to obtain films by PECs casting/evaporation process. For films obtained from the whole suspension, by increasing the xylan content the stress at break is improved (up to 23 MPa for 85/15, at pH 7.0) and the strain at break is decreased (to 2.5%). When only coacervate is used to prepare films, the tensile strength is higher, reaching a value of 37 MPa for 85/15 mass ratio. Dynamic mechanical thermal analysis shows that the glass transition temperature (Tg) of the films is affected by composition. The thermoplastic behavior of a 50/50 xylan/PEI film is confirmed using a hot-compression molding.Fil: Solier, Yamil Nahún. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Mocchiutti, Paulina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Inalbon, Maria Cristina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Zanuttini, Miguel Angel Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentin

Alkali-peroxide treatment of sugar cane bagasse : Effect of chemical charges on the efficiency of xylan isolation and susceptibility of bagasse to saccharification

Sugar cane is a promising raw material for the extraction of hemicelluloses. An alkali treatment of sugar cane bagasse under proper conditions followed by a precipitation using a reasonable quantity of ethanol can be an effective method to isolate these polysaccharides. In this work, bagasse is treated to obtain two products: (a) polymeric hemicellulose and (b) an enzymatic hydrolysate from the treated bagasse after hemicellulose extraction. The effects of charges of sodium hydroxide (10, 20, 40% w/w) and hydrogen peroxide (0, 10, 20% w/w) in the alkali treatment were evaluated. A 3² experimental design was considered under control of metal ions and inert atmosphere during alkaline treatment. An acceptable proportion of xylose plus arabinose could be extracted from bagasse (up to 18.4 g/100 g of bagasse). Both the alkali and peroxide showed strong effects on the yield of the extraction, as well as on the yield of the precipitation in ethanol-water solution. Besides, the susceptibility of bagasse for cellulolytic enzymatic hydrolysis is improved. The highest hemicellulose precipitation yield was 85% which corresponded to the treatment with the highest alkali charge without peroxide. The highest yield of enzymatic hydrolysis was obtained for the highest alkali and peroxide charges.Instituto de Fisiología VegetalInstituto de Botánica "Dr. Carlos Spegazzini

Obtaining and characterization of hemicelluloses from sugar cane bagsue for use in bio-based materials

Fil: Solier, Yamil Nahún. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina.La presente tesis pretende hacer un aporte importante, mediante la aplicación del concepto de biorrefineria, estudiando una alternativa para el aprovechamiento del bagazo de caña de azúcar, un recurso lignocelulósico que se genera en los ingenios azucareros y que actualmente está destinado a la producción de energía (como combustible húmedo de caldera) y en algunos pocos casos a la producción de papel. Se evaluó específicamente la obtención de hemicelulosas y su viabilidad para la elaboración de películas biobasadas con posibilidad potencial de sustitución de materiales de origen no renovable. Se consideró la aplicación de estas películas para uso en embalaje donde se requiere que sean manipulables y con suficiente resistencia en seco y en húmedo y además posean aceptables propiedades de barrera al vapor de agua. Con el objetivo de estudiar un aprovechamiento integral del bagazo de caña de azúcar, se analizó la hidrólisis enzimática del bagazo ya tratado para la obtención de azúcares fermentables, con la posibilidad de ser utilizados en la generación de alcohol. De esta forma, partiendo de un residuo de la industria, se podría obtener un proceso integral, que genere diferentes productos de interesante valor. En esta Tesis particularmente se obtuvo xilano (que demostró ser apto para la obtención de materiales biobasados) y por otro lado, azúcares fermentables con potencial utilización en la obtención de alcohol.This thesis aims to make an important contribution, through the application of the biorefinery concept, studying an alternative for the use of sugarcane bagasse, a lignocellulosic resource that is generated in sugar mills and is currently used for energy production. (as wet boiler fuel) and in a few cases to the production of paper. The obtaining of hemicelluloses and their viability for the elaboration of biobased films with the potential possibility of substituting materials which come from non-renewable resources was specifically evaluated. The application of these films was considered for use in packaging where it is required that they be manipulable and with sufficient dry and wet strength and also have acceptable water vapor barrier properties. In order to study a comprehensive use of sugarcane bagasse, the enzymatic hydrolysis of bagasse which was previously treated was analyzed to obtain fermentable sugars, with the possibility of being used in the generation of alcohol. In this way, starting from a waste from the industry, an integral process could be obtained, which generates different products of interesting value. In this thesis, in particular, xylan was obtained (which proved to be suitable for obtaining biobased materials) and, on the other hand, fermentable sugars with potential use in obtaining alcohol.Consejo Nacional de Investigaciones Científicas y Técnica

Hydrothermal treatment of Eucalyptus wood: Effects on Ion permeability and material removing

Hemicelluloses, the second most abundant polysaccharides in nature after cellulose, can be used for hydrogels, in packaging-films, or biomedical materials, among other purposes. In the case of eucalyptus wood, glucuronoxylans are the main constituents of hemicellulose. Hot water extraction can be used as a pretreatment for purposes of hydrolysis of the biomass followed by fermentation and also as a previous stage in pulping processes. The influence of auto hydrolysis/extraction has been widely studied for different lignocellulosic materials, but the characteristics of the hydrolyzate and aspects like change in wood permeability have not been analyzed in detail. This paper analyzes the hydrothermal treatment of Eucalyptus grandis chips and slices under mild conditions, considering temperature and time range corresponding to a Pfactor of up to 350. The ion permeability of the treated wood slices and its profile in wood chip, as well as the amount of hemicellulose and lignin dissolved from chips are evaluated. The amount of the hemicelluloses and lignin extracted was increased as treatment was intensified. For a Pfactor higher than 180, the increment in the extracted xylan is clear but the colloidal electric charge in the liquor is reduced due to xylan degradation. Total extracted lignin can be up to 3.0 g/100 g of original wood and the hemicelluloses 6.5 g xylose/100 g of original wood, respectively. The permeability of wood slices is clearly increased by water treatment. In the chip, the diffusion restriction leads to a permeability profile, and the increase at the proximity of the outer faces can be higher compared to that in the chip core.Fil: Inalbon, Maria Cristina. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Solier, Yamil Nahún. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zanuttini, Miguel Angel Mario. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sulfation of poplar wood xylan using a deep eutectic solvent: effects of the degree of substitution on the properties of biobased hydrogels

Xylan sulfation using a Deep Eutectic Solvent (DES), formed by sulfamic acid and urea (1:2 molar ratio), was investigated with different reagent dosages (xylan/sulfamic acid molar ratio 1:10 and 1:5) and time (30 and 60 min). The effect of xylan/reagent ratio on the degree of substitution (DS) was higher than time, varying from 0.4 to 1.1. NMR spectra confirmed that the sulfate group was introduced into the C-2 and C-3 of the xylose moieties. Polyelectrolyte complex suspensions were prepared using the different sulfated xylan (SXyl) and chitosan (Ch) (mass ratio 55 SXyl/45 Ch) and deeply characterized. It was found that a precipitate was obtained for moderate conditions of sulfation; however for the others, stable suspensions were formed. Hydrogels with acceptable dry and wet mechanical properties (up to 45 MPa and 6 MPa of resistance, and 10% and 90% of elongation, respectively), and thermal properties were produced. Differences in crystallinity as well as in water uptake at 75% RH, depending on the SXyl used, were found. Promising results for potential use in drug delivery were the swelling capacity, which reached a maximum of 384% and was directly related to the degree of substitution of xylan, and the high water-resistant.Fil: Solier, Yamil Nahún. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Sznaider, Frank. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Navarro, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Mocchiutti, Paulina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Inalbon, Maria Cristina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Alkali-peroxide extraction of xylan from sugar cane bagasse: Characteristics and film forming capacity

This work analyzes the main characteristics of hemicellulose alkali and peroxide/alkali extracted from sugar cane bagasse and precipitated by 1:1 ethanol/liquor ratio and studies the influence of the chemical charge on these characteristics. It also evaluates the film forming capacity of these hemicelluloses when they are combined in a polyelectrolyte complex with chitosan. Extraction conditions were determinant of the glucuronic acid to xylose ratio and arabinose to xylose ratio. The charge density of xylan, determined by polyelectrolyte titration at pH 7.0, showed a linear relation with the glucuronic acid content. Xylans with low polydispersity and acceptable molecular weight were obtained in all cases. Hemicellulose-based films (70% of xylan) without the addition of plasticizer or crosslinking agent, obtained through the controlled formation of the polyelectrolyte complexes, were flexible with acceptable mechanical properties. The film with the highest stress and strain at break (19.1 MPa and 10.7%, respectively) corresponded to hemicellulose with the highest molecular weight, extracted with the highest alkali charge and no peroxide addition.Fil: Solier, Yamil Nahún. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Schnell, Carla Natali. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Cabrera, María Noel. Universidad de la Republica; UruguayFil: Zanuttini, Miguel Angel Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Inalbon, Maria Cristina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

High strength biobased films prepared from xylan/chitosan polyelectrolyte complexes in the presence of ethanol

The effect of different ethanol concentrations (0; 3; 9; 12 and 16 wt%) on the degree of ionization of xylan and chitosan, the characteristics of polyelectrolyte complex (PEC) suspensions, and the derived films, were exhaustively analyzed through several analytical techniques. Results indicate that the degree of ionization of both polyelectrolytes was reduced, whereas particle sizes and z-potential values of PEC suspensions were remarkably modified. As ethanol concentration was increased up to 12 wt%, the crystallinity of films decreased. Furthermore, the stress at break increased from 45 to 75 MPa. Wet stress-strain results were promising (up to 5.0 MPa, 55%) for all films. Although water vapor permeability was not modified, the swelling capacity was favorably reduced (12%). Results reveal that, for preparing films, it might not be necessary to remove all the ethanol used for xylan precipitation and purification.Fil: Schnell, Carla Natali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Galván, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Solier, Yamil Nahún. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Inalbon, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Zanuttini, Miguel Angel Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Mocchiutti, Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentin

Fast preparation of flexible wet-resistant and biodegradable films from a stable suspension of xylan/chitosan polyelectrolyte complexes

Novel hemicellulose-based flms from polyelectrolyte complexes (PECs) of chitosan and xylan from sugar cane bagasse were prepared and characterized. PEC suspension from two diferent xylan to chitosan mass ratios (70/30 and 80/20) were considered. With the aim of shorten the whole flm preparation process, PEC suspension was concentrated through a fast evaporation stage before casting. Results show that the concentration stage did not modify neither the size of the complexes, i.e., a size distribution with a mode at 450 nm and other at 5000 nm, nor the mechanical properties of the flms. By the increment in xylan content from 70 to 80%, the strain at break was decreased (up to a value of 7%), the stress at break was increased (up to 22 MPa) and the swelling of the flms was increased from 80 to 90%. After 25 days under aerobic burial conditions, degradation of the flms was similar to cellulose.Fil: Solier, Yamil Nahún. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Schnell, Carla Natali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Galván, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Mocchiutti, Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Zanuttini, Miguel Angel Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; ArgentinaFil: Inalbon, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentin

Alkali-peroxide treatment of sugar cane bagasse. Effect of chemical charges on the efficiency of xylan isolation and susceptibility of bagasse to saccharification

Sugar cane is a promising raw material for the extraction of hemicelluloses. An alkali treatment of sugar cane bagasse under proper conditions followed by a precipitation using a reasonable quantity of ethanol can be an effective method to isolate these polysaccharides. In this work, bagasse is treated to obtain two products: (a) polymeric hemicellulose and (b) an enzymatic hydrolysate from the treated bagasse after hemicellulose extraction. The effects of charges of sodium hydroxide (10, 20, 40% w/w) and hydrogen peroxide (0, 10, 20% w/w) in the alkali treatment were evaluated. A 32 experimental design was considered under control of metal ions and inert atmosphere during alkaline treatment. An acceptable proportion of xylose plus arabinose could be extracted from bagasse (up to 18.4 g/100 g of bagasse). Both the alkali and peroxide showed strong effects on the yield of the extraction, as well as on the yield of the precipitation in ethanol-water solution. Besides, the susceptibility of bagasse for cellulolytic enzymatic hydrolysis is improved. The highest hemicellulose precipitation yield was 85% which corresponded to the treatment with the highest alkali charge without peroxide. The highest yield of enzymatic hydrolysis was obtained for the highest alkali and peroxide charges.Fil: Solier, Yamil Nahún. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Mocchiutti, Paulina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Cabrera, María Noel. Universidad de la Republica. Facultad de Ingeniería; UruguayFil: Saparrat, Mario Carlos Nazareno. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; ArgentinaFil: Zanuttini, Miguel Angel Mario. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Inalbon, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología Celulósica; Argentin

Effect of Oxalic Acid Concentration and Different Mechanical Pre-Treatments on the Production of Cellulose Micro/Nanofibers

The present work analyzes the effect of process variables and the method of characterization of cellulose micro/nanofibers (CMNFs) obtained by different treatments. A chemical pre-treatment was performed using oxalic acid at 25 wt.% and 50 wt.%. Moreover, for mechanical pre-treatments, a rotary homogenizer or a PFI mill refiner were considered. For the mechanical fibrillation to obtain CMNFs, 5 and 15 passes through a pressurized homogenization were considered. The best results of nanofibrillation yield (76.5%), transmittance (72.1%) and surface charges (71.0 µeq/g CMNF) were obtained using the PFI mill refiner, 50 wt.% oxalic acid and 15 passes. Nevertheless, the highest aspect ratio (length/diameter) determined by Transmission Electron Microscopy (TEM) was found using the PFI mill refiner and 25 wt.% oxalic acid treatment. The aspect ratio was related to the gel point and intrinsic viscosity of CMNF suspensions. The values estimated for gel point agree with those determined by TEM. Moreover, a strong relationship between the intrinsic viscosity [η] of the CMNF dispersions and the corresponding aspect ratio (p) was found (ρ[η] = 0.014 p2.3, R2 = 0.99). Finally, the tensile strength of films obtained from CMNF suspensions was more influenced by the nanofibrillation yield than their aspect ratio