The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Fabrizio Cavani - One of the best experts on this subject based on the ideXlab platform.

Sergio Sanchez Segado - One of the best experts on this subject based on the ideXlab platform.

  • fabricacion de bioalcohol a partir de la vaina del algarrobo y ii fermentacion alcoholica del extracto acuoso
    Ingenieria Quimica, 2008
    Co-Authors: D De Juan Garcia, Luis Javier Lozano Blanco, Sergio Sanchez Segado
    Abstract:

    Se presenta, en esta segunda parte del articulo sobre la obtencion de bioalcohol a partir de la vaina del fruto del algarrobo, el estudio experimental de la fermentacion alcoholica del extracto acuoso. El presente articulo pretende mostrar que es posible realizar la transformacion alcoholica de los azucares extraidos de una forma sencilla y con una velocidad y rendimiento aceptable. En trabajos previos por nuestro grupo de investigacion [1 y 2] se ha propuesto la preparacion de bioalcohol a partir de la vaina del fruto del algarrobo, desarrollando un metodo operativo para realizar la extraccion acuosa de los azucares solubles en agua en ella contenidos. El siguiente paso logico a realizar para comprobar la certeza de nuestra aseveracion inicial es conseguir realizar la transformacion alcoholica de los azucares extraidos de una forma sencilla, y con una velocidad y rendimiento, tanto industrial como economico, aceptable. El proposito del presente articulo es mostrar que esta transformacion de los azucares extraidos es industrialmente posible.

  • fabricacion de bioalcohol a partir de la vaina del algarrobo i extraccion acuosa de los azucares solubles
    Ingenieria Quimica, 2008
    Co-Authors: Diego Juan Garcia, Luis Javier Lozano Blanco, Sergio Sanchez Segado
    Abstract:

    Se ha propuesto la preparacion de bioalcohol a partir de la vaina del fruto del algarrobo, realizando la extraccion acuosa de los azucares solubles en agua en ella contenidos. Se ha verificado la caracterizacion fisica y quimica de la vaina de algarrobo, un modelo de la cinetica de su lixiviacion una vez premolida y su aplicacion en laboratorio. Finalmente, se describen las caracteristicas de las lejias azucaradas obtenidas

Olena Vozniuk - One of the best experts on this subject based on the ideXlab platform.

Rafael M Maderocastro - One of the best experts on this subject based on the ideXlab platform.

  • the role of hydrogen bonding in the dehydration of Bioalcohols in hydrophobic pervaporation membranes
    Journal of Molecular Liquids, 2021
    Co-Authors: Rafael M Maderocastro, Sofia Calero, Ozgur A Yazaydin
    Abstract:

    Abstract The dehydration of Bioalcohols is considered one of the major factors contributing to the cost of biofuel production. In this study, liquid phase separation of water from methanol and ethanol in a siliceous MFI pervaporation membrane was studied by performing concentration gradient driven molecular dynamic (CGD-MD) simulations. CGD-MD simulations work by imposing a higher concentration in the feed side and a lower concentration in the permeate side of the membrane. This creates a concentration gradient across the membrane that facilitates the diffusion of molecules from the feed to the permeate side, mimicking the experimental pervaporation membrane set up. Fluxes of methanol, ethanol and water were calculated in single component permeation simulations and in equimolar methanol–water and ethanol–water mixture separation simulations. It was found that water formed hydrogen bonds with the silanol (Si-OH) groups on the external surface of the MFI and did not enter the membrane in the single component permeation simulation. While this may suggest that MFI can be used to effectively dehydrate Bioalcohols, our simulations showed that water permeated through the MFI membrane when it was in a mixture with either methanol or ethanol. Furthermore, in the alcohol-water mixture simulations, the fluxes of methanol and ethanol were significantly lower than that of expected based on their single component fluxes. A detailed analysis of hydrogen bonding in the alcohol-water mixture separation simulations revealed that water preferred making hydrogen bonds with methanol and ethanol rather than with the silanol groups. This resulted in drifting of water molecules along with permeating alcohol molecules in to the MFI membrane in mixture simulations, while slowing the permeation of methanol and ethanol fluxes. The hydrogen bonding between water and alcohol molecules indicates that it may not be possible to achieve complete alcohol selectivity even if defect-free membranes were manufactured; however, our findings also hint at the possibility of functionalizing membrane surfaces with chemical groups that will overcome water-alcohol hydrogen bonding and retain water molecules in order to approach complete selectivity.

  • the role of hydrogen bonding in the dehydration of Bioalcohols in hydrophobic pervaporation membranes
    ChemRxiv, 2021
    Co-Authors: Rafael M Maderocastro, Sofia Calero, Ozgur A Yazaydin
    Abstract:

    The dehydration of Bioalcohols is considered one of the major factors contributing to the cost of biofuel production. In this study, liquid phase separation of water from methanol and ethanol in a siliceous MFI pervaporation membrane was studied by performing concentration gradient driven molecular dynamic (CGD-MD) simulations. CGD-MD simulations work by imposing a higher concentration in the feed side and a lower concentration in the permeate side of the membrane. This creates a concentration gradient across the membrane that facilitates the diffusion of molecules from the feed to the permeate side, mimicking the experimental pervaporation membrane set up. Fluxes of methanol, ethanol and water were calculated in single component permeation simulations and in equimolar methanol-water and ethanol-water mixture separation simulations. It was found that water formed hydrogen bonding with the silanol (Si-OH) groups on the external surface of the MFI and did not enter the membrane in the single component permeation simulation. While this may suggest that MFI can be used to effectively dehydrate Bioalcohols, our simulations showed that water permeated through the MFI membrane when it was in a mixture with either methanol or ethanol. Furthermore, in the alcohol-water mixture simulations, the fluxes of methanol and ethanol were significantly lower than that of expected based on their single component fluxes. A detailed analysis of hydrogen bonding in the alcohol-water mixture separation simulations revealed that water preferred making hydrogen bonds with methanol and ethanol rather than with the silanol groups. This resulted in drifting of water molecules along with permeating alcohol molecules in to the MFI membrane in mixture simulations, while slowing the permeation of methanol and ethanol fluxes.

Sebastian Sanchez - One of the best experts on this subject based on the ideXlab platform.

  • production of Bioalcohols and antioxidant compounds by acid hydrolysis of lignocellulosic wastes and fermentation of hydrolysates with hansenula polymorpha
    Engineering in Life Sciences, 2019
    Co-Authors: Ma Lourdes Martinezcartas, Ma Inmaculada Olivares, Sebastian Sanchez
    Abstract:

    The effect of the H2SO4 concentration in the hydrolysis of sunflower-stalk waste, at 95oC and using a liquid/solid relation of 20, was studied. In a later stage, the hydrolysates were fermented at different temperatures with the aim of ethanol and xylitol production. A total conversion of the hemicellulose at the acid concentration of 0.5 mol/L was achieved; whereas an acid concentration of 2.5 mol/L was needed to reach the maximum value in the conversion of the cellulose fraction. The analysis of the hydrolysis kinetics has enabled to determine the apparent reaction order, which was 1.3. The hydrolysates from hydrolysis process with H2SO4 0.5 mol/L, once detoxified, were fermented at pH 5.5, temperatures 30, 40, and 50oC with the yeast Hansenula polymorpha (ATCC 34438), resulting in a sequential uptake of sugars. In relation to ethanol and xylitol yields, the best results were observed at 50°C ( YE/sO  = 0.11 g/g;  YXy/sO  = 0.12 g/g). Instantaneous xylitol yields were higher than in ethanol, at the three temperatures essayed. Different phenolic compounds were analyzed in the hydrolysates; hydroxytyrosol was the most abundant (3.79 mg/L). The recovery of these compounds entails the elimination of inhibitors in the fermentation process and the production of high value-added antioxidant products.

  • Comparing Bioalcohols Production from Olive Pruning Biomass by Biotechnological Pathway with Candida guilliermondii and Pichia stipitis
    Waste and Biomass Valorization, 2016
    Co-Authors: Alberto J. Moya, Soledad Mateo, Juan G. Puentes, Bruno G. Fonseca, Inês Conceição Roberto, Sebastian Sanchez
    Abstract:

    After acid hydrolysis with \(\hbox {H}_2\hbox {SO}_4\) from olive pruning, subsequent fermentations were carried out in order to compare two non-traditional yeasts: Candida guilliermondii and Pichia stipitis. During the fermentations, sugar uptake as well as ethanol and xylitol production were determined. However, both yeast employed for the biotransformations showed different behaviours; C. guilliermondii produced ethanol from D-glucose and xylitol from D-xylose but, in contrast, P. stipitis only was able to produce ethanol from hexoses and pentoses although, due to the inhibitors amount (acetic acid and polyphenols mainly), it required a detoxification step. To solve this problem, activated charcoal treatment as well as a vacuum evaporation process (concentration ratio 2.7) were performed as physical detoxification methods with positive results. The maximum ethanol and xylitol yields (\(Y_{P/S}\)) (calculated on consumed sugars) obtained with C. guilliermondii were 0.38 and 0.31 kg \(\hbox {kg}^{-1}\) respectively; while P. stipitis was able to produce 0.33 kg of ethanol per kg of fermentable sugar.

  • production of xylitol and ethanol by hansenula polymorpha from hydrolysates of sunflower stalks with phosphoric acid
    Industrial Crops and Products, 2012
    Co-Authors: Ma Lourdes Martinez, Sebastian Sanchez, Vicente Bravo
    Abstract:

    Abstract This research analyses the effect exerted by the phosphoric acid concentration (CAo) in sunflower-stalk hydrolysis at 95 °C, considering the results in relation to the yields in d -glucose and total reducing sugars (TRS). Besides to display the behavior of the yeast in generating Bioalcohols from hydrolysates rich in nutrients such as phosphate, essential for the growth of yeasts in fermentation processes. The results show that the hydrolysis of the hemicellulose fraction was almost complete at CAo = 2.67 mol/L (25.3%), at which conversion reached 82.7%. The percentage of converted cellulose also increased with the acid concentration, reaching a value of 13.9% in the hydrolysis process of 2.67 mol/L. The hydrolysis rate (rH) was calculated from the values of the concentration of total reducing sugars generated over the process. For a value of CAo = 1.67 mol/L, it was determined that (rH)max = 3.5 g TRS/(L h) at the beginning of the hydrolysis process. After being detoxified, the hydrolysates were fermented with Hansenula polymorpha, ATCC 34438, registering better results in the production of ethanol that of xylitol. For an initial concentration of total reducing sugars of 13.3 g/L, xylitol yield was 0.023 g/g, and ethanol yield was 0.14 g/g.