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de Vasconcelos S.M.,Federal University of Pernambuco | Santos A.M.P.,Federal University of Pernambuco | Rocha G.J.M.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Souto-Maior A.M.,Federal University of Pernambuco
Bioresource Technology | Year: 2013

The influence of time (8-24. min), temperature (144-186. °C) and phosphoric acid concentration (0.05-0.20%, w/v) on the pretreatment of sugarcane bagasse in a 20. L batch rotary reactor was investigated. The efficiency of the pretreatment was verified by chemical characterization of the solid fraction of the pretreated bagasse and the conversion of cellulose to glucose by enzymatic hydrolysis. Models representing the percentage of cellulose, hemicelluloses, lignin, solubilized hemicellulose and the enzymatic conversion of cellulose to glucose were predictive and significant. Phosphoric acid concentration of 0.20% at temperature of 186. °C, during 8 and 24. min, was shown to be very effective in solubilizing hemicellulose from sugarcane bagasse, reaching solubilization of 96% and 98%, respectively. Relatively low amounts of inhibitors were produced, and the phosphoric acid remaining in the hemicellulosic hydrolysate is at adequate levels for supplying phosphorous requirement during subsequent fermentation. © 2012 Elsevier Ltd.


Driemeier C.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Bragatto J.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Journal of Physical Chemistry B | Year: 2013

Relating cellulose structure to its water uptake is a classical problem with many investigations done through measurements of cellulose "crystallinity". However, there is presently a growing consensus that crystallinity measurements are appreciably uncertain, leading to ambiguous interpretations of underlying cellulose organization. In this scenario, this article revisits the relations between cellulose structure and water uptake, moving the emphasis away from degree of crystallinity and directing it toward crystallite width, which is inferred with less ambiguity from the broadening of 200 X-ray diffraction peaks. With this approach, analysis of a wide spectrum of celluloses isolated from plants (preserving cellulose I phase and having variable contents of residual hemicelluloses) reveals a simple linear relation (R2 = 0.98) between reciprocal crystallite width and monolayer hydration (determined from vapor sorption). The primary role of crystallite width supports that most water-accessible polysaccharides are laterally associated with the crystallites, with a minor fraction in disordered domains along the fibrils. Furthermore, the secondary role left to hemicellulosic contents indicates cellulose being partly decrystallized to complement the disordered amount required to interface the crystallites. Finally, a substantial part of hydration is attributed to polysaccharides in voids left by the imperfect packing of aggregated crystallites. © 2012 American Chemical Society.


Moraes B.S.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Zaiat M.,University of Sao Paulo | Bonomi A.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Renewable and Sustainable Energy Reviews | Year: 2015

The replacement of fossil fuels by biofuels has been extremely important worldwide to stimulate the growth of economies based on the sustainability through the use of renewable resources. Anaerobic digestion for biogas production is recognized as a clean technology that allies the suitability of wastes with energy generation, fulfilling the requirements for a sustainable alternative to provide the optimization of the biofuels production. This alternative is especially interesting for the sugarcane ethanol production in Brazil, in which the generation of vinasse, the main liquid waste, is very expressive. Nevertheless, the use of vinasse for anaerobic digestion has been finding some challenges to its establishment in the Brazilian sugarcane biorefineries. This paper reviews the actual context of anaerobic digestion within the sugarcane ethanol production in Brazil, presenting the main obstacles for its full application and the directions to promote it as well. Alternatives for biogas use are also presented and compared, highlighting the environmental and energy advantages of applying anaerobic digestion in the sugarcane biorefineries. This scenario is envisaged as a suitable way to achieve the future biorefineries model, based on the use and recovery of renewable resources with economic, social, and environmental benefits. © 2015 Elsevier Ltd. All rights reserved.


Leal M.R.L.V.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Horta Nogueira L.A.,Federal University of Itajubá | Cortez L.A.B.,University of Campinas
Applied Energy | Year: 2013

Several key indicators of the sustainability of biofuels are related to the land used to produce the feedstock. Most of the agronomic costs and energy use (fertilizers, herbicides, soil preparation, and harvesting) are more related to the cropped area than to the feedstock quantity produced; this is also the case of soil greenhouse gas (GHG) emissions (CO2 and N2O) and land use change (LUC) impacts, both direct (dLUC) and indirect (iLUC), socio-economic impacts (land tenure, land prices and traditional crop displacement), impacts on biodiversity and on the environment (soil, water and air). Today, biofuels use only a little more than 2% of the world arable land but if their use to displace fossil fuels increases, as indicated by some low carbon scenarios, the land demand for the production of feedstocks could become a constraint to the expansion. It is quite apparent that the biofuel yields, present and future, should be one of the main characteristics to be evaluated in the initial screening process. This work uses the cases of corn and sugarcane ethanol to draw some comparisons on the use of these biofuels to meet the targets of some of the International Energy Agency (IEA) biofuel use scenarios in terms of land demand and also will use some of the most important study results concerning the GHG emission reduction potential, including LUC and iLUC impacts, when meeting the Renewable Energy Directive (RED) of the European Union (EU) and the Renewable Fuel Standard (RFS2) of the USA. Some technology improvements will be considered including the integration of first and second generation technologies in the same site processing corn or sugarcane for ethanol. The results of the simulations indicated that the land demands for the 2030 projected ethanol production in the two alternatives seems not to give reasons for concern on a global scale, but are large enough to produce significant local impacts. The GHG abatement potential is strongly dependent on the biofuel alternative considered. © 2012 Elsevier Ltd.


Oliveira R.P.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Driemeier C.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Journal of Applied Crystallography | Year: 2013

Cellulose from higher plants is a vast renewable resource organized as crystals. Analysis of these crystals by X-ray diffraction poses very specific challenges, including ubiquitous crystallite texture and substantial overlapping of diffraction peaks. In this article, a tailor-made model named Cellulose Rietveld Analysis for Fine Structure (CRAFS) is developed to analyze two-dimensional X-ray diffraction patterns from raw and processed plant cellulose. One-dimensional powder diffractograms are analyzable as a particular case. The CRAFS model considers cellulose Iβ crystal structure, fibrillar crystal shape, paracrystalline peak broadening, pseudo-Voigt peak profiles, harmonic crystallite orientation distribution function and diffraction in fiber geometry. Formulated on the basis of the Rietveld method, CRAFS is presently written in the MATLAB computing language. A set of meaningful coefficients are output from each analyzed pattern. To exemplify model applicability, representative samples are analyzed, bringing some general insights and evidencing the model's potential for systematic parameterization of the fine structure of raw and processed plant celluloses. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.


Levaton J.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Amorim J.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Chemical Physics | Year: 2012

We have studied by optical emission spectroscopy the post-discharge of a pure N 2 DC flowing discharge in such experimental conditions that the pink afterglow and the Lewis-Rayleigh afterglow occur. The emission profiles originated from the N 2B 3Πg, N 2C 3Πu and N2+B 2Σu+ states and the N 2B 3Πg,6≤v≤12 and N 2C 3Πu,0≤v≤4 vibrational distributions were obtained in the post-discharge region. With basis on the works of Bockel et al. [S. Bockel, A.M. Diamy, A. Ricard, Surf. Coat. Tech. 74 (1995) 474] and Amorim and Kiohara [J. Amorim, V. Kiohara, Chem. Phys. Lett. 385 (2004) 268], we have obtained the experimental N( 4S) and N( 2D) relative densities along the post-discharge. A numerical model, previously developed to describe the neutral atomic, molecular and ionic species in the afterglow, was improved to include the kinetics of N( 2D) and N( 2P) states. Several kinetic mechanisms leading to the production of N( 2D) in the post-discharge have been studied in order to explain the experimental data. We have determined that the dominant one is the reaction N 2X 1Σg+,v>8+N( 4S)→N 2X 1Σg++N( 2D) with an estimated rate constant of 7 × 10 -14 cm 3 s -1. Also, the fit of the numerical density profiles of N 2C 3 Πu and N2+B 2Σu+ to the experimental ones has provided the rate constant for reaction N 2A 3Σ u++N 2X 1∑g+,v>18→N 2C 3Πu+N 2X 1Σg+. Its estimated value is 4 × 10 -13 cm 3 s -1. Finally, with the new kinetic scheme, we have found that the ionization in the post-discharge region has important contribution of N( 2D) and N( 2P) species. © 2011 Elsevier B.V. All rights reserved.


Furtado A.T.,University of Campinas | Scandiffio M.I.G.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Cortez L.A.B.,University of Campinas
Energy Policy | Year: 2011

Ethanol has recently been of great interest worldwide because it is a viable economic alternative to petroleum products and it is a renewable source of energy that mitigates the emission of greenhouse gases. Brazilian bioethanol from sugarcane is the most successful case at the world level because of its low cost and low level of greenhouse gas emissions. Brazil's success with sugarcane cannot be understood as based solely on a natural comparative advantage, but as a result of efforts that culminated in a positive trajectory of technological learning, relying mostly on incremental innovations. The purpose of this article is to analyze the key aspects of the innovation system built around the Brazilian sugarcane industry. It is based on the national innovation systems approach according to which innovation results from the interaction of different institutional actors. Institutional arrangements are analyzed as the basis for the innovative process, in particular R&D and the innovation policies and strategies of the main players in the sugarcane sector, including sugar and ethanol mills, industrial goods suppliers, public and private research institutions, and governmental agencies. © 2010 Elsevier Ltd.


Driemeier C.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Calligaris G.A.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Journal of Applied Crystallography | Year: 2011

This work defines the crystallinity of cellulose I materials on a dry-weight basis. Theoretical and experimental developments in X-ray diffraction lead to a crystallinity determination method that is estimated to reach 1 accuracies of better than 0.05 (crystallinity defined between 0 and 1). The method is based on Rietveld modelling, to resolve cellulose I Bragg peaks, and a standard truncated invariant integral. Corrections are derived to account for incoherent scattering, moisture content and other compositional deviations from pure cellulose. The experimental development uses X-ray diffraction in transmission fibre geometry with two-dimensional pattern Rietveld modelling, including a crystal-orientation distribution function. The crystallinities of a few commercial cellulose I materials were determined with the aim of illustrating the applicability of the method. © 2011 International Union of Crystallography Printed in Singapore-all rights reserved.


Driemeier C.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Cellulose | Year: 2014

The Rietveld method is a versatile tool to parameterize the fine structure of crystallites analyzed by diffraction. The method relies on a crystallographic model representing what is known a priori, and free coefficients determined from fits to experimental data. This article provides an introduction to Rietveld analysis of celluloses from higher plants that are adequately described by the cellulose Iβ crystal structure. Possibilities of Rietveld analysis have been recently enhanced by a tailored crystallographic model and computational algorithm, named Cellulose Rietveld Analysis for Fine Structure (CRAFS). From each two-dimensional diffraction pattern, CRAFS automated analysis outputs unit cell parameters, crystallite sizes, peak profile functions, integrated crystalline intensity (proportional to cellulose degree of crystallinity), and crystallite orientation distribution function. Two of the major hurdles for analysis of plant cellulose-overlapping of diffraction peaks and preferred crystallite orientation-are consistently treated by the two-dimensional Rietveld analysis. Hence, the method is a unique tool to explore cellulose fine structural variability, with differences arising from specimen conditioning, processing, and biological origins. © 2013 Springer Science+Business Media Dordrecht.


Souza S.P.,University of Campinas | Souza S.P.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Seabra J.E.A.,University of Campinas | Seabra J.E.A.,CTBE - Brazilian Bioethanol Science and Technology Laboratory
Applied Energy | Year: 2013

The biorefinery of the future will be an integrated complex that makes a variety of products (e.g., biofuels, chemicals, power and protein) from a variety of feedstocks. The objective of this work was to evaluate the environmental benefits, compared to the traditional sugarcane ethanol system, of the integrated production of ethanol and biodiesel through a sugarcane-soybean biorefinery concept in Brazil. The environmental aspects considered here were the fossil energy use and the greenhouse gases (GHGs) emissions associated with ethanol production. In the Integrated System, soybean would be cultivated in part of the sugarcane reforming areas, which represents ∼17% of the total sugarcane area. Sugarcane and soybean oil would be processed in a combined ethanol-biodiesel plant, which would use only bagasse as fuel. All the demand for utilities of the biodiesel plant would be provided by the distillery. The output products of the combined plant would comprise sugarcane ethanol, soybean biodiesel (which would be used as diesel (B5) substitute in the sugarcane cultivation), bioelectricity and glycerin. The results indicate that the Integrated System can reduce the fossil energy consumption from 75 to 37kJ/MJ of ethanol, when compared to the traditional system. For GHG emissions, the value would drop from 22.5 to 19.7g CO2eq/MJ of ethanol. This analysis shows that the Integrated System is an important option to contribute to ethanol's life cycle independence from fossil resources. This is an attractive environmental aspect, but socio-economic (as well as other environmental) aspects should also be analyzed in order to assess the sustainability of such systems in a broader perspective. © 2012 Elsevier Ltd.

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