Papers by Ursula Fabiola Rodríguez Zúñiga
Cristiane Sanches Farinas Todos os direitos reservados. A reprodução não-autorizada desta publica... more Cristiane Sanches Farinas Todos os direitos reservados. A reprodução não-autorizada desta publicação, no todo ou em parte, o constitui violação dos direitos autorais (Lei n 9.610). CIP-Brasil. Catalogação-na-publicação. Embrapa Instrumentação Agropecuária Farinas, Cristiane Sanches Avaliação de diferentes resíduos agroindustriais como substratos para a produção de celulases por fermentação semi-sólida.
Influência dos solos podzólicos no ciclo geoquímico das substâncias húmicas aquáticas do Rio Negro-AM
Lignin adsorption and enzymatic saccharification of in house produced cellulolytic enzymes with novel and conventional methods
Agradeço ao Dr. Silvio Crestana pela oportunidade concedida, orientação, e a cordialidade com que... more Agradeço ao Dr. Silvio Crestana pela oportunidade concedida, orientação, e a cordialidade com que sempre me recebeu. Estou grata também pela iniciativa do trabalho e liberdade de ação decisiva para o meu desenvolvimento pessoal. À Dra. Cristiane Farinas, amiga e co-orientadora pela disposição em me encaminhar nas atividades e cuja dedicação, apoio e amizade tornaram possível a concretização deste projeto. Ao Dr. Victor Bertucci Neto, pela disponibilização do bioreator de colunas acompanhamento e apoio contínuos durante todo o doutorado. À Dra. Sonia Couri por ceder o A. niger e pelas sugestões, críticas e incentivo e à equipe da Embrapa Agroindústria de Alimentos, em especial a Dra. Mônica Damaso e a Dra. Selma Terzi. Ao Dr. José Manuel Marconcini, que gentilmente cedeu o bagaço de cana para a experimentação deste trabalho. A Embrapa Pecuária Sudeste, ao Dr. Gilberto, Cristina, Victor e Mariana pelo auxilio no trabalho de análise de materiais lignocelulósicos. Ao IQSC pelas instalações nas análises de caracterização, ao Prof. Antonio Aprígio pelo apoio com o laboratório de Físico
BioEnergy Research, 2014
The chemical composition of pretreated sugarcane bagasse (SCB), in terms of cellulose, hemicellul... more The chemical composition of pretreated sugarcane bagasse (SCB), in terms of cellulose, hemicellulose and lignin, was analyzed using a fast near-infrared spectroscopy (NIR) technique. Spectra of four types of SCB, prepared using ammonia, hydrothermal, organosolv and sodium hydroxide pretreatments, were correlated with classical chemical analysis using partial least squares regression (PLS). In a novel approach, isolation of the components used to prepare synthetic samples of SCB permitted assessment of their influence on the model. Inclusion of the synthetic samples did not improve the performance of the model, due to structural differences such as chemical bonding and physical interactions between the components. For natural pretreated samples, the PLS technique showed good predictive capacity, with ranges (%, w/w) of 47.2-89.4 (cellulose), 0.2-27.0 (hemicellulose), and 2.1-30.0 (lignin), and low root-mean-square error values of 4.1, 3.8, and 3.5, respectively, demonstrating the suitability of using different pretreated samples in the same calibration model.
Agradeço ao Dr. Silvio Crestana pela oportunidade concedida, orientação, e a cordialidade com que... more Agradeço ao Dr. Silvio Crestana pela oportunidade concedida, orientação, e a cordialidade com que sempre me recebeu. Estou grata também pela iniciativa do trabalho e liberdade de ação decisiva para o meu desenvolvimento pessoal. À Dra. Cristiane Farinas, amiga e co-orientadora pela disposição em me encaminhar nas atividades e cuja dedicação, apoio e amizade tornaram possível a concretização deste projeto. Ao Dr. Victor Bertucci Neto, pela disponibilização do bioreator de colunas acompanhamento e apoio contínuos durante todo o doutorado. À Dra. Sonia Couri por ceder o A. niger e pelas sugestões, críticas e incentivo e à equipe da Embrapa Agroindústria de Alimentos, em especial a Dra. Mônica Damaso e a Dra. Selma Terzi. Ao Dr. José Manuel Marconcini, que gentilmente cedeu o bagaço de cana para a experimentação deste trabalho. A Embrapa Pecuária Sudeste, ao Dr. Gilberto, Cristina, Victor e Mariana pelo auxilio no trabalho de análise de materiais lignocelulósicos. Ao IQSC pelas instalações nas análises de caracterização, ao Prof. Antonio Aprígio pelo apoio com o laboratório de Físico
Avaliação da influência de fatores ambientais na estrutura, dinâmica e propriedades ópticas das substâncias húmicas aquáticas do Rio Negro
Green Chem., 2015
Sugarcane bagasse, corn stover, and wheat straw are among the most available resources for the pr... more Sugarcane bagasse, corn stover, and wheat straw are among the most available resources for the production of cellulosic ethanol. For these biomasses we study the influence of pre-treatment methods on the chemical composition, as well as on the subsequent reactions of enzymatic hydrolysis and oxidation of cellulose. The applied pre-treatment methods are organosolv, hydrothermal, and alkaline. Hydrothermally pretreated wheat straw gave the highest cellulose conversion with 80% glucose yield and 0.8% oxidized cellulose products. Recent studies have shown that lignin is able to boost the activity of the cellulose oxidizing enzyme lytic polysaccharide monooxygenase (LPMO). The highest activity of LPMO was observed for the hydrothermally pretreated biomasses, which also contained the highest level of lignin. All hydrolyses were done at high dry matter levels using a commercial enzyme preparation containing hydrolytic and oxidative enzymes. † These authors contributed equally to this work.
Optimal Bioreactor Operational Policies for the Enzymatic Hydrolysis of Sugarcane Bagasse
BioEnergy Research, 2013
ABSTRACT The consolidation of the industrial production of second-generation (2G) bioethanol reli... more ABSTRACT The consolidation of the industrial production of second-generation (2G) bioethanol relies on the improvement of the economics of the process. Within this general scope, this paper addresses one aspect that impacts the costs of the biochemical route for producing 2G bioethanol: defining optimal operational policies for the reactor running the enzymatic hydrolysis of the C6 biomass fraction. The use of fed-batch reactors is one common choice for this process, aiming at maximum yields and productivities. The optimization problem for fed-batch reactors usually consists in determining substrate feeding profiles, in order to maximize some performance index. In the present control problem, the performance index and the system dynamics are both linear with respect to the control variable (the trajectory of substrate feed flow). Simple Michaelis–Menten pseudo-homogeneous kinetic models with product inhibition were used in the dynamic modeling of a fed-bath reactor, and two feeding policies were implemented and validated in bench-scale reactors processing pre-treated sugarcane bagasse. The first approach applied classical optimal control theory. The second policy was defined with the purpose of sustaining high rates of glucose production, adding enzyme (Accellerase® 1500) and substrate simultaneously during the reaction course. A methodology is described, which used economical criteria for comparing the performance of the reactor operating in successive batches and in fed-batch modes. Fed-batch mode was less sensitive to enzyme prices than successive batches. Process intensification in the fed-batch reactor led to glucose final concentrations around 200 g/L.
Brazilian Journal of Chemical Engineering, 2013
This work presents a kinetic study of the enzymatic hydrolysis of three cellulosic substrates: fi... more This work presents a kinetic study of the enzymatic hydrolysis of three cellulosic substrates: filter paper (FP), used as a low recalcitrance substrate model; steam exploded sugarcane bagasse (SB); and weak acid pretreated SB (1:20 dry bagasse:H 2 SO 4 solution 1% w/w), the last two delignified with 4% NaOH (w/w). The influence of substrate concentration was assessed in hydrolysis experiments in a shaker, using Accellerase® 1500, at pH 4.8, in 50 mM sodium citrate buffer. Cellulose loads (weight substrate /weight total ) were changed between 0.5%-13% (for FP) and 0.99%-9.09% (for SB). For FP and low loads of steam exploded SB, it was possible to fit pseudo-homogeneous Michaelis-Menten models (with inhibition). For FP and higher loads of steam exploded SB, modified Michaelis-Menten models were fitted. Besides, it was observed that, after retuning of the model parameters, it is possible to apply a model fitted for one situation to a different case. Chrastil models were also fitted and they were the only feasible approach for the highly recalcitrant acid-treated SB.
Environmental Science & Technology, 2008
Aquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winte... more Aquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winter and summer corresponding to floody and dry periods, were structurally characterized by 13 C nuclear magnetic ressonance. Subsequently, AHS aqueous solutions were irradiated with a polychromatic lamp (290-475 nm) and monitored by its total organic carbon (TOC) content, ultraviolet-visible (UV-vis) absorbance, fluorescence, and Fourier transformed infrared spectroscopy (FTIR). As a result, a photobleaching up to 80% after irradiation of 48 h was observed. Conformational rearrangements and formation of low molecular complexity structures were formed during the irradiation, as deduced from the pH decrement and the fluorescence shifting to lower wavelengths. Additionally a significant mineralization with the formation of CO 2 , CO, and inorganic carbon compounds was registered, as assumed by TOC losses of up to 70%. The differences in photodegradation between samples expressed by photobleaching efficiency were enhanced in the summer sample and related to its elevated aromatic content. Aromatic structures are assumed to have high autosensitization capacity effects mediated by the free radical generation from quinone and phenolic moieties.
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Papers by Ursula Fabiola Rodríguez Zúñiga