Centro UTN QUIMOBI - Difusión Científica - Trabajos Presentados en Congresos
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Item Preliminary tests of production of cellulosic bioethanol for testing simultaneous hydrolysis and fermentation(2015-11-23) Arismendy, Ana María; Felissia, Fernando; Area, María; Chamorro, EsterIt is necessary to find valid renewable sources that do not compete with food production at affordable costs and alternatives, to help alleviate the exhaustion of fossil fuels. Cellulosic biomass can be chemically or enzymatically hydrolyzed and then the sugars obtained fermented with yeasts to produce ethanol. The possibility of hydrolysis and fermentation simultaneous presents the advantage like, prevents inhibition of enzymes, reduces the risk of pollution and decreases production costs. The drawback is that the optimum temperature for the enzyme treatment is about 50°C, while the corresponding fermentation is close to 32°C Rice husks, lignocellulosic waste of rice production, are abundant in the Argentina NEA region and an excellent raw material for the bioethanol production because it has a high cellulose content. In order to realize in the future enzymatic hydrolysis and fermentation in one step with rice husks, it have been performed preliminary tests of enzymatic hydrolysis on Whatman filter paper N°1 at temperatures below the optimum (32°C), and subsequent fermentation with four different yeast, Saccharomyces cerevisiae, Candida tropycalis, Candida guilliermondii and Candida kefir, at the same temperature. The selection of yeast was performed according to specific criteria. Candida kefir can bear temperatures up to 37°C, which was taken like feasible alternative for realizing of simultaneous process in the future at high temperatures. The Candida and Saccharomyces work at 32°C, but also have affinity for 5-carbon sugars such as xylose, which are present in small amounts if the material has been pretreated with acid to remove hemicellulose. The filter paper characterization was determinated through amount of moisture, and ash and then was realized the hydrolysis during 72 hours at 32ºC on a rotary shaker, using enzymes, like celullases of Trichoderma reseei and celobiasses of Aspergillus níger. The subsequent fermentation was performed in the supernatant of the hydrolysis, supplemented with nutrients and the four yeasts listed above for 24 hours at 32 ° C, with the same stirring used. The amount of glucose obtained in the hydrolysis was determinate by High Performance Liquid Chromatography (HPLC) with refractive index (IR) detector. In the hydrolysis at 32°C the cellulose conversion to glucose was 81%. The results of ethanol generated by the fermentation were determinated by HPLC and the percentaje of ethanol obtained of each fermentation with each yeast were of 66.22% for Saccharomyces cerevisiae, Candida kéfyr 50.15%, Candida guilliermondii 45% and Candida tropycalis 61.47%. The results show that all yeasts generated ethanol, even when the fermentation time was only 24 hours. In the hydrolysis at 32°C were obtained encouraging results, as in fermentation for 24 hours at the same temperature. Based on these results was realized the simultaneous processing with rice hulks to 48 hours with temperatures between 35 and 37°C.Item Optimization of the soda-ethanol delignification in the biorefinery of rice husk(2015-11-23) Dagnino, Eliana Paola; Felissia, Fernando; Chamorro, Ester; Area, MaríaLignocellulosic materials are an interesting alternative to obtain products with high added value, such as bioethanol, food and cosmetics additives, and adhesives, among many others. Rice hulls (RHs) is an abundant residue in the Argentine Northeast region (provinces of Corrientes, Entre Rios, Santa Fe, Formosa and Chaco). Rice production in Argentina in 2012/13 reached 1,397,242 tons, of which about 20% was RHs [1]. RHs is composed of 48.7% carbohydrates (34.1% cellulose and 14.6% hemicelluloses), 17.2% and 1.8% of insoluble and soluble lignin acid respectively, 15% of inorganic components, and others [2], so the application of the biorefinery concept, i.e. the separation and valorization of its individual components, is of high interest. Delignification of RHs pretreated with acid (previously optimized process) [2] was carried out using an organosolv soda-ethanol process. This treatment is advantageous since the reaction is faster, it uses smaller amount of soda than the conventional soda process, and the ethanol can be recovered and reused. A Central Composite Experiment Design of two variables with three replicas of the center point was used. Soda concentrations between 9 and 17g per liter, and ethanol concentrations between 46 and 60% were evaluated. The liquor was placed in a reactor of AISI 316 stainless steel of 180ml, with a closing screw gauge. It was heated in a heat resistant silicone bath to 160°C. The reaction time was 60min, and it was necessary around additional 25min to reach 160°C. The mixture was then cooled in a cold water bath and filtered through a 100 mesh sieve. The solid was washed repeatedly to remove the remaining solution. The concentration of residual lignin (NREL process/TP-510-42618) in the pretreated solid was measured as response variable and delignification relative to initial lignin was calculated on this basis. The results were analyzed using multivariate analysis of variance (ANOVA). Statgraphics statistical software was used, with a level of significance of 95%. The adjusted model explained the 92% of the variability. Both variables showed significant effect (p ≤ 0.05) on the residual lignin in the treated solid. The percentage of delignification ranged from 63% in the treatment with 13g/l NaOH and 46% EtOH; to 87% in the treatment with 13g/l NaOH and 53% EtOH. The optimal response corresponded to 13g/l NaOH (center point) and 50% EtOH (-0.8 as coded variable), with a 3.26% theoreticalvalue of the residual lignin in the solid pretreated and an 87.9% of deslignification. In conclusion, the sequence acid / soda-ethanol allowed hemicelluloses extraction in the first stage and lignin extraction in the second stage. The residual solid was composed almost entirely of cellulose with approximately 25% of inorganic components, which will be separated in future studies, to fully implement the biorefinery concept