Browsing by Author "Vele Salto, Angélica María"

Now showing 1 - 5 of 5

Estudio de la influencia del tiempo en la reacción de hidrólisis ácida para la obtención de glucosa a partir de la cáscara de cacao
(Universidad de Cuenca, 2023-01-12) Acevedo Lazo, Valeria Elizabeth; Once Bueno, Paola Lisseth; Vele Salto, Angélica María
The main objective of the present project was to determine the influence of the reaction time in the acid hydrolysis stage of the cocoa shell, which it was started by sampling the cocoa cobs in the Putucay parish located near the La Troncal canton. Subsequently, the samples were pretreated, by drying and size reduction and then determining their chemical composition, where results of 21,57 % extractable, 27,59 % lignin, 21,65 % cellulose, and 13,58 % hemicellulose were obtained. Then, the acid hydrolysis reaction was performed under conditions of 4% v/v sulfuric acid, at 100°C in a discontinuous reactor of perfect mixture, with variable reaction time in the range of 0 to 70 minutes. The hydrolyzed liquid was analyzed by High-Performance Liquid Chromatography (HPLC) resulting in a maximum glucose concentration of 4,40 g / L for 30 minutes. On the other hand, by means of the linear regression integration method, the kinetics of the hydrolysis reaction was determined to be of second order (n = 2) with a velocity constant k = 0,0032 g -1 min-1 . Finally, the solid residue of the hydrolysis reaction was chemically characterized for times within the kinetic region, reaching a lignin content of 49,54% and 49,96% holocellulose.
Evaluación de la ecuación de Arrhenius en la hidrólisis ácida de los residuos de piña
(Universidad de Cuenca, 2024-11-18) Correa Jaramillo, John Michael; Quito Inchiglema, Micaela Alejandra; Vele Salto, Angélica María
In this research, two types of biodegradable raw materials were evaluated: peel (CC) and crown (CR) from pineapple, with the aim of substituting fossil raw materials use in fuels production. The samples were characterized by determining the content of lignin, cellulose, hemicellulose and ash. It was determined that the sample with the highest cellulose content in its structure was the crown, with a content of 23.50%. From this, acid hydrolysis was carried out with this waste (CR) to obtain glucose, using H2SO4 at 5%, experimenting with temperatures of 30, 50, 70 and 92.5 °C, and reaction time of 0, 50, 90, 120 and 150 minutes. The highest concentration obtained was 3.03 g/L of glucose, at 92.5 °C and 120 min. Subsequently, the kinetic study was conducted using Saeman method to obtain the kinetic constants k1 and k2. Finally, using the constant k1 and linearized Arrhenius equation, the activation energy was quantified as Ea = 10.06 KJ mol-1, and the pre-exponential factor as Ao = 0.12 min-1 .
Evaluación de la efectividad de los solventes en la eliminación de extractivos y su relación con la caracterización química de bagazo de caña de azúcar
(Universidad de Cuenca, 2022-01-18) Cabrera Salazar, Evelyn Priscila; Chamba Ramírez, Karen Belén; Vele Salto, Angélica María
This project evaluates the effectiveness of three types of solvents (water, 95 % ethanol and the 1:2 ethanol-toluene mixture) which are used in the elimination of extractives (gums, tannins, colorants, sugars, starches, essential oils, waxes) and, in turn, its relationship with the chemical characterization of sugarcane bagasse is analyzed. To carry out this analysis, a biomass sampling was carried out at the Los Faiques factory located on the Girón Pasaje road in the Santa Isabel canton of the Azuay province, then the sample was pretreated for size reduction and moisture determination, allowing the correct elimination of extractives, and their subsequent chemical characterization that consisted in determining the percentage in weight of cellulose, hemicellulose and lignin, for this, the standards TAPPI 204, TAPPI 222, TAPPI 212 and ASTM 1104 were applied. The results obtained showed that the sugarcane bagasse presents a humidity of 55.86 % and the solvent that eliminated a greater quantity of extractables was the 1:2 ethanol-toluene mixture, whose percentage was 31.61%, on the other hand, it was determined that the contents of cellulose, hemicellulose and lignin reached values of up to 38.67 %, 36.03 % and 13.60 % respectively, in the samples treated with said solvent, because it was possible to eliminate the greatest amount of interferences in the previous stage. The research carried out reflected that there is a dependence between the elimination of extractives and the chemical characterization, since when using ethanol-toluene as a solvent, a greater amount of extractables eliminated was obtained, therefore, this solvent is ideal for this type of biomass, obtaining a more reliable amount of lignocellulosic constituents than those achieved in the samples treated with the other two solvents, due to the interferences eliminated, highlighting cellulose as the most important.
Mini revisión: aplicación de líquidos iónicos en hidrólisis ácida dematerial lignocelulósico para la obtención de azúcares
(2021) Salamea Piedra, Teresita Silvana; Vele Salto, Angélica María; Pinos Vélez, Verónica Patricia; Abril González, Mónica Fernanda
In recent decades, the application of ionic liquids (IL) as pretreatment of residual biomass (BM) before the hydrolysis reaction hasproven to be an efficient system to improve yields towards obtaining monosaccharides. A greater recovery of monosaccharidestranslates into a higher yield in the production of biofuels, which can make this industry profitable. In this context, this bibliographicreview analyzes the physicochemical characteristics, synthesis methods, dissolution conditions with application of variables, suchas: IL: BM weigh ratio, temperature and time. In addition, a comparative assessment of the results of traditional acid hydrolysisprocesses with respect to those obtained with the application of IL is carried out, increasing in most cases their reaction yields.Finally, some recovery and recycling techniques are mentioned, which allow to reduce the costs of the process, so that it iseconomically profitable
Obtención de glucosa mediante la hidrólisis ácida con líquidos iónicos a partir de material lignocelulósico
(Universidad de Cuenca, 2024-11-27) Tapia Coellar, Viviana Geovanna; Vásquez Zúñiga, Keatklin Mireya; Vele Salto, Angélica María
The main objective of this project was to obtain glucose from cacao pods through acid hydrolysis using ionic liquids (IL). Samples were collected in the canton "Camilo Ponce Enríquez" and their chemical composition was determined, resulting in 23,67% extractives, 41,37% lignin, 29,36% cellulose, and 9,76% hemicellulose. Subsequently, the samples were hydrolyzed with 5% v/v sulfuric acid, both in the absence and presence of the ionic liquid 1- ethyl-3-methylimidazolium ethyl sulfate, in a 10:1 ratio, at 94°C. The reactions were carried out in a batch reactor with perfect mixing for times ranging from 0 to 120 minutes. Glucose determination was performed using High-Performance Liquid Chromatography (HPLC), obtaining a maximum glucose concentration of 1,88 g/L at 100 minutes without IL and 2,19 g/L at 80 minutes with IL. The reaction kinetics were determined using the integral method and the Saeman method, yielding an 2=0,94 without IL and 2=0,96 with IL for a first-order reaction, and 2=0,91 without IL and 2=0,85 with IL for the Saeman method. Finally, the mass balance indicated a cellulose conversion of 10,91% with a reaction time of 61,20 minutes without IL, and 15,20% in 77,97 minutes with IL, while the energy balance showed a heat transfer rate of 0,91 J/min for hydrolysis without IL and 1,60 J/min with IL.