Limpieza de membranas de ultrafiltración aplicadas en la industria alimentaria por medio de técnicas no convencionales y caracterización del ensuciamiento de las membranas

Tesis por compendio[EN] In this PhD Thesis, the application of two non conventional techniques (saline solutions and electric fields) to clean ultrafiltration membranes that were previously fouled with whey model solutions was investigated. In addition, the membrane fouling caused by the different model solutions was studied as well. This fouling was characterised by fitting different semi-empirical mathematical models to the experimental data of permeate flux evolution with time. Experiments were performed at a laboratory scale with four ultrafiltration membranes of different material (ceramic and organic) and molecular weight cut-off (5, 15, 30 and 50 kDa) and three different whey model solutions consisting of aqueous solutions of bovine serum albumin (BSA), BSA with CaCl2 and whey protein concentrate (WPC). Each experiment was divided in four steps: fouling with the model solution, first rinsing, cleaning and second rinsing. Experimental conditions during the first stage were the same in all the cases, so that it could be determined the influence of the experimental conditions during the cleaning step (type of saline solution, salt concentration, cleaning solution temperature, crossflow velocity and potential of the electric field) on the cleaning efficiency. The mathematical models considered were the Hermia's models adapted to crossflow filtration, a combined model based on Hermia's equations of complete pore blocking and cake formation and a resistance-in-series model. The results obtained during the fouling step demonstrated that the mathematical models used were able to predict with high accuracy the permeate flux decline with time. The value of the model characteristic parameters and the fouling mechanisms mainly responsible for that decline were determined. Regarding the cleaning experiments for the membranes used, the results indicated that both, saline solutions and electric fields, were effective techniques to recover the membrane permselective properties when an optimal salt concentration range was considered.[ES] En la presente Tesis Doctoral se investigó la aplicación de dos técnicas no convencionales (disoluciones salinas y campos eléctricos) para limpiar membranas de ultrafiltración que previamente habían sido ensuciadas con disoluciones modelo de lactosuero. Además, se estudió el ensuciamiento de las membranas causado por las diferentes disoluciones ensayadas, caracterizando el mismo mediante el ajuste de distintos modelos matemáticos semi-empíricos a los resultados experimentales de variación de la densidad de flujo de permeado con el tiempo. Los ensayos se realizaron a escala de laboratorio con cuatro membranas de ultrafiltración de diferente material (cerámicas y orgánicas) y umbral de corte molecular (5, 15, 30 y 50 kDa) y con tres disoluciones modelo de lactosuero consistentes en disoluciones acuosas de seroalbúmina bovina (BSA), BSA con CaCl2 y concentrado de proteínas de lactosuero (WPC). Cada ensayo fue dividido en cuatro etapas: ensuciamiento con la disolución modelo, primer aclarado, limpieza y segundo aclarado. Las condiciones experimentales durante la primera etapa fueron las mismas en todos los casos, para poder evaluar la influencia de las condiciones experimentales durante la etapa de limpieza (tipo de disolución salina, concentración de sal, temperatura de la disolución, velocidad tangencial y potencial de campo eléctrico aplicado) en la eficacia del proceso de limpieza. Los modelos matemáticos considerados fueron los modelos de Hermia adaptados a flujo tangencial, un modelo combinado basado en las ecuaciones de Hermia de bloqueo completo de poros y formación de torta y un modelo de resistencias en serie. Los resultados obtenidos durante la etapa de ensuciamiento demostraron que los modelos matemáticos utilizados son capaces de predecir con una elevada exactitud el descenso de la densidad de flujo de permeado con el tiempo, determinándose el valor de los parámetros característicos de dichos modelos y los mecanismos de ensuciamiento responsables principalmente de dicho descenso. En cuanto a los ensayos de limpieza de las membranas utilizadas, los resultados indicaron que tanto las disoluciones salinas como los campos eléctricos son técnicas efectivas para recuperar las propiedades permselectivas de las membranas, utilizando un intervalo de concentración de sal óptimo.[CA] En la present Tesi Doctoral es va investigar l'aplicació de dues tècniques no convencionals (dissolucions salines i camps elèctrics) per a netejar membranes d'ultrafiltració que prèviament havien sigut embrutades amb dissolucions model de sèrum de llet. A més, es va estudiar l'embrutament de les membranes causat per les diferents dissolucions assajades, caracteritzant el mateix mitjançant l'ajust de distints models matemàtics semi-empírics als resultats experimentals de variació de la densitat de flux de permeat amb el temps. Els experiments es realitzaren a escala de laboratori amb quatre membranes d'ultrafiltració de diferent material (ceràmiques i orgàniques) i umbral de tall molecular (5, 15, 30 i 50 kDa) i amb tres dissolucions model de sèrum de llet consistents en dissolucions aquoses de seroalbúmina bovina (BSA), BSA amb CaCl2 i concentrat de proteïnes de sèrum de llet (WPC). Cada experiment fou dividit en quatre etapes: embrutament amb la dissolució model, primer aclarat, neteja i segon aclarat. Les condicions experimentals durant la primera etapa van ser les mateixes en tots els casos, per a poder evaluar la influència de les condicions experimentals durant l'etapa de neteja (classe de dissolució salina, concentració de sal, temperatura de la dissolució, velocitat tangencial i potencial de camp elèctric aplicat) en l'eficàcia del procés de neteja. Els models matemàtics utilitzats varen ser els models d'Hermia adaptats a flux tangencial, un model combinat basat en las equacions d'Hermia de bloqueig complet de porus i formació de torta i un model de resistències en serie. Els resultats obtinguts durant l'etapa d'embrutament demostraren que els models matemàtics utilitzats són capaços de predir amb una elevada exactitud el descens de densitat de flux de permeat amb el temps, determinant-se el valor dels paràmetres característics dels citats models i els mecanismes d'embrutament responsables principalment del citat descens. En quant als experiments de neteja de les membranes utilitzades, els resultats indicaren que tant les dissolucions salines com els camps elèctrics són tècniques efectives per a recuperar les propietats permselectives de les membranes, utilitzant un interval de concentració de sal òptim.Corbatón Báguena, MJ. (2015). Limpieza de membranas de ultrafiltración aplicadas en la industria alimentaria por medio de técnicas no convencionales y caracterización del ensuciamiento de las membranas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54841TESISPremios Extraordinarios de tesis doctoralesCompendi

Evaluation of fouling resistances during the ultrafiltration of whey model solutions

[EN] In the last decades, the ultrafiltration of whey has grown in importance as a "green" technique. However, since fouling is an important drawback, researchers focused on its prediction by mathematical models. In this work, three ultrafiltration membranes of different molecular weight cut-offs and materials were used to ultrafilter whey model solutions of different protein concentrations. As a novelty, a resistance-in-series model that accounts for the time evolution of the fouling resistances was considered. The results demonstrated that the higher the protein and salt concentrations in the feed solutions were, the greater the fouling degree was. The resistance-in-series model was accurately fitted to the experimental data for each membrane and feed solution used. The results showed that the resistance due to adsorption dominated the first minutes of operation, while the membrane characteristics (surface roughness and hydrophilicity/hydrophobicity) played an important role in the growth of the cake layer. (C) 2017 Elsevier Ltd. All rights reserved.The authors of this work wish to gratefully acknowledge the financial support provided by the Spanish Ministry of Science and Innovation through its project CTM2010-20186.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC. (2018). Evaluation of fouling resistances during the ultrafiltration of whey model solutions. Journal of Cleaner Production. 172:358-367. https://doi.org/10.1016/j.jclepro.2017.10.149S35836717

Destabilization and removal of immobilized enzymes adsorbed onto polyethersulfone ultrafiltration membranes by salt solutions

In this work the effectiveness of two saline solutions (NaCl and Na2SO4) to clean a permanently hydrophilic polyethersulfone (PESH) ultrafiltration (UF) membrane with a molecular weight cut-off (MWCO) of 30 kDa previously fouled with enzymatic solutions was investigated. The influence of protein concentration in the enzymatic solution during the fouling step and the effect of salt type during the cleaning procedure were studied. The protein aggregation was analyzed in solution and onto the membrane surface by using several techniques including Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM) and Infrared Spectroscopy with Attenuated Total Reflectance (ATR-FTIR). In addition, mechanisms that dominate membrane fouling were studied by fitting some mathematical models (Hermia's models adapted to crossflow filtration, a combined model based on the complete blocking and cake formation equations and a resistance-in-series model) to the experimental data. Fouling results showed that the complete blocking/adsorption on membrane surface was the predominant fouling mechanism. Regarding the cleaning results, higher cleaning efficiency and low residual protein concentration was obtained with NaCl solutions for all the feed solutions tested due to the favorable interaction between Cl and proteins.Maria-Jose Corbaton-Baguena wishes to gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the grant EEBB-I-14-09011 (project CTM2010-20186). The authors acknowledge the European Union, Fondo Europeo di Sviluppo Regionale, The Ministero dell'Istruzione, dell'Universita e della Ricerca - MIUR, The Ministero dello Svilupppo Economic - MSE - for the financial support to the project "Sistemi tecnologici avanzati e processi integrati della filiera olivicola per la valorizzazione dei prodotti e dei sottoprodotti, lo sviluppo di nuovi settori e la creazione di sistemi produttivi Eco-compatibili" (PON Olio Piu, PON01_01545), within the framework PON Ricerca e Competitivita 2007-2013.Corbatón Báguena, MJ.; Gugliuzza, A.; Cassano, A.; Mazzei, R.; Giorno, L. (2015). Destabilization and removal of immobilized enzymes adsorbed onto polyethersulfone ultrafiltration membranes by salt solutions. Journal of Membrane Science. 486:207-214. https://doi.org/10.1016/j.memsci.2015.03.061S20721448

Utilization of NaCl solutions to clean ultrafiltration membranes fouled by whey protein concentrates

In this work, whey protein concentrate (WPC) solutions at different concentrations (22.2, 333 and 150 g L-1) were used to foul three ultrafiltration (UF) membranes of different materials and molecular weight cut-offs (MWCOs): a polyethersulfone (PES) membrane of 5 kDa, a ceramic ZrO2-TiO2 membrane of 15 kDa and a permanently hydrophilic polyethersulfone (PESH) membrane of 30 kDa. NaCl solutions at different salt concentrations, temperatures and crossflow velocities were used to clean the UF membranes tested. The cleaning efficiency was related to the MWCO, membrane material and operating conditions during fouling and cleaning steps. NaCl solutions were able to completely clean the membranes fouled with the WPC solutions at the lowest concentration tested. As WPC concentration increased, the hydraulic cleaning efficiency (HCE) decreased. The results demonstrated that an increase in temperature and crossflow velocity of the cleaning solution caused an increase in the HCE. Regarding NaCl concentration, the HCE increased up to an optimal value. As the concentration was greater than this value, the cleaning efficiency decreased. In addition, an equation that correlates the cleaning efficiency to the operating parameters studied in this work (temperature, NaCl concentration, crossflow velocity in the cleaning procedure and WPC concentration during the fouling step) was developed and then, an optimization analysis was performed to determine the values of the parameters that lead to a 100% cleaning efficiency.The authors of this work wish to gratefully acknowledge the financial support from the Spanish Ministry of Science and Innovation through the project CTM2010-20186.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC.; Lora-García, J. (2015). Utilization of NaCl solutions to clean ultrafiltration membranes fouled by whey protein concentrates. Separation and Purification Technology. 150:95-101. https://doi.org/10.1016/j.seppur.2015.06.039S9510115

Analysis of two ultrafiltration fouling models and estimation of model parameters as a function of operational conditions

This work analyses the measure of fit of experimental data of permeate flux decline with time for ultrafiltration experiments performed with polyethylene glycol aqueous solutions to two different ultrafiltration models. A feed solution of 5 kg/m of polyethylene glycol and a monotubular ceramic membrane of - were used in the experiments. The first model considered was developed by Ho and Zydney and it considers two different fouling mechanisms: pore blocking and gel layer formation. The second model was proposed by Yee et al. It is an exponential model that considers three stages: concentration polarization, molecule deposition on the membrane surface and long-term fouling. The results show that both models give very accurate predictions for the severe fouling conditions (high transmembrane pressures and low crossflow velocities). However, both models cannot explain the experimental results obtained for all the experimental conditions tested. An equation for Ho and Zydney's model parameters as a function of operating conditions was obtained by means of multiple regression analysis.The authors of this work wish to gratefully acknowledge the financial support of the Universidad Politecnica de Valencia through the Project No. 2010.1009 and the Spanish Ministry of Science and Technology through the project CTM2010-20186.Corbatón Báguena, MJ.; Vincent Vela, MC.; Alvarez Blanco, S.; Lora García, J. (2013). Analysis of two ultrafiltration fouling models and estimation of model parameters as a function of operational conditions. Transport in Porous Media. 99(2):391-411. https://doi.org/10.1007/s11242-013-0192-4S391411992Alventosa-deLara, E., Barredo-Damas, S., Alcaina-Miranda, M.I., Iborra-Clar, M.I.: Ultrafiltration technology with a ceramic membrane for reactive dye removal: optimization of membrane performance. J. Hazard. Mater. 209–210, 492–500 (2012)Baldasso, C., Barros, T.C., Tessaro, I.C.: Concentration and purification of whey proteins by ultrafiltration. Desalination 278, 381–386 (2011)Bhattacharjee, C., Datta, S.: Analysis of polarized layer resistance during ultrafiltration of PEG-6000: an approach based on filtration theory. Sep. Purif. Technol. 33, 115–126 (2003)Buetehorn, S., Carstensen, F., Wintgens, T., Melin, T., Volmering, D., Vossenkaul, K.: Permeate flux decline in crossflow microfiltration at constant pressure. Desalination 250, 985–990 (2010)Chan, R., Chen, V.: Characterization of protein fouling on membranes: opportunities and challenges. J. Membr. Sci. 242, 169–188 (2004)Cheryan, M.: Ultrafiltration and Microfiltration Handbook. Technomic Publishing Company, Inc., Lancaster (1998)de Barros, S.T.D., Andrade, C.M.G., Mendes, E.S., Peres, L.: Study of fouling mechanism in pineapple juice clarification by ultrafiltration. J. Membr. Sci. 215, 213–224 (2003)de la Casa, E.J., Guadix, A., Ibáñez, R., Camacho, F., Guadix, E.M.: A combined fouling model to describe the influence of the electrostatic environment on the cross-flow microfiltration of BSA. J. Membr. Sci. 318, 247–254 (2008)Espina, V., Jaffrin, M.Y., Ding, L., Cancino, B.: Fractionation of pasteurized skim milk proteins by dynamic filtration. Food Res. Int. 43, 1335–1346 (2010)Fernández-Sempere, J., Ruiz-Beviá, F., García-Algado, P., Salcedo-Díaz, R.: Visualization and modeling of the polarization layer and a reversible adsorption process in PEG-10000 dead-end ultrafiltration. J. Membr. Sci. 342, 279–290 (2009)Field, R.W., Wu, D., Howell, J.A., Gupta, B.B.: Critical flux concept for microfiltration fouling. J. Membr. Sci. 100, 259–272 (1995)Hermia, J.: Constant pressure blocking filtration laws—application to powerlaw non-Newtonian fluids. Trans. IChemE 60, 183–187 (1982)Ho, C.-C., Zydney, A.L.: A combined pore blockage and cake filtration model for protein fouling during microfiltration. J. Colloid Interface Sci. 232, 389–399 (2000)Karasu, K., Yoshikawa, S., Ookawara, S., Ogawa, K., Kentish, S.E., Stevens, G.W.: A combined model for the prediction of the permeation flux during the cross-flow ultrafiltration of a whey suspension. J. Membr. Sci. 361, 71–77 (2010)Ko, M.K., Pellegrino, J.J.: Determination of osmotic pressure and fouling resistances and their effects on performance of ultrafiltration membranes. J. Membr. Sci. 74, 141–157 (1992)Lin, S.-H., Hung, C.-L., Juang, R.-S.: Applicability of the exponential time dependence of flux decline during dead-end ultrafiltration of binary protein solutions. Chem. Eng. J. 145, 211–217 (2008)Mondal, S., De, S.: A fouling model for steady state crossflow membrane filtration considering sequential intermediate pore blocking and cake formation. Sep. Purif. Technol. 75, 222–228 (2010)Mondor, M., Girard, B., Moresoli, C.: Modeling flux behaviour for membrane filtration of apple juice. Food Res. Int. 33, 539–548 (2000)Muthukumaran, S., Kentish, S.E., Ashokkumar, M., Stevens, G.W.: Mechanisms for the ultrasonic enhancement of dairy whey ultrafiltration. J. Membr. Sci. 258, 106–114 (2005)Peng, H., Tremblay, A.Y.: Membrane regeneration and filtration modeling in treating oily wastewaters. J. Membr. Sci. 324, 59–66 (2008)Popović, S., Milanović, S., Iličić, M., Djurić, M., Tekić, M.: Flux recovery of tubular ceramic membranes fouled with whey proteins. Desalination 249, 293–300 (2009)Purkait, M.K., DasGupta, S., De, S.: Resistance in series model for micellar enhanced ultrafiltration of eosin dye. J. Colloid Interface Sci. 270, 496–506 (2004)Rinaldoni, A.N., Taragaza, C.C., Campderrós, M.E., Pérez, Padilla A.: Assessing performance of skim milk ultrafiltration by using technical parameters. J. Food Eng. 92, 226–232 (2009)Santafé-Moros, A., Gozálvez-Zafrilla, J.M.: Nanofiltration study of the interaction between bicarbonate and nitrate ions. Desalination 250, 773–777 (2010)Song, L.: Flux decline in crossflow microfiltration and ultrafiltration: mechanisms and modeling of membrane fouling. J. Membr. Sci. 139, 183–200 (1998)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Gozálvez Zafrilla, J.M., Bergantiños, Rodríguez E.: Modelling of flux decline in crossflow ultrafiltration of macromolecules: comparison between predicted and experimental results. Desalination 204, 328–334 (2007a)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Gozálvez Zafrilla, J.M., Bergantiños, Rodríguez E.: Utilization of a shear induced diffusion model to predict permeate flux in the crossflow ultrafiltration of macromolecules. Desalination 206, 61–68 (2007b)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Analysis of membrane pore blocking models applied to the ultrafiltration of PEG. Sep. Purif. Technol. 62, 489–498 (2008a)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Fouling dynamics modelling in the ultrafiltration of PEGs. Desalination 222, 451–456 (2008b)Vincent Vela, M.C., Álvarez, Blanco S., Lora, García J., Bergantiños, Rodríguez E.: Analysis of membrane pore blocking models to crossflow ultrafiltration in the ultrafiltration of PEG. Chem. Eng. J. 149, 232–241 (2009)Vincent-Vela, C., Cuartas-Uribe, B., Álvarez-Blanco, S., Lora-García, J., Bergantiños-Rodríguez, E.: Analysis of ultrafiltration processes with dilatant macromolecular solutions by means of dimensionless numbers and hydrodynamic parameters. Sep. Purif. Technol. 75, 332–339 (2010)Wang, L., Song, L.: Flux decline in crossflow microfiltration and ultrafiltration: experimental verification of fouling dynamics. J. Membr. Sci. 160, 41–50 (1999)Yee, K.W.K., Wiley, D.E., Bao, J.: A unified model of the time dependence of flux decline for the long-term ultrafiltration of whey. J. Membr. Sci. 332, 69–70 (2009

Application of electric fields to clean ultrafiltration membranes fouled with whey model solutions

In this work, the effectiveness of electric fields to clean two ZrO2 TiO2 ultrafiltration (UF) membranes fouled with three types of whey model solutions was investigated. Membranes tested had different molecular weight cut-offs (MWCOs) (15 and 50 kDa). Whey model solutions consisted of aqueous solutions of bovine serum albumin (BSA) at 10 g/L, a mixture of BSA (10 g/L) and CaCl2 (1.65 g/L) and whey protein concentrate (WPC) (total protein content 45%) solutions at different concentrations (22.2, 33.3 and 150.0 g/L). The hydraulic cleaning efficiency (HCE) achieved by means of the application of the electric fields was evaluated as a function of the membrane MWCO and the operating conditions of the cleaning technique (applied potential, temperature of the cleaning solution and concentration of NaCl). The results demonstrated that the presence of NaCl favoured the removal of protein deposits on the membrane layer. On the other hand, the higher the temperature of the cleaning solution and the applied potential were, the higher HCE was achieved. Regarding the membrane MWCO, the permselective properties of the 15 kDa membrane were completely recovered after the cleaning procedure by electric field for all the feed fouling solutions tested, whereas this technique could not completely remove the protein deposits on the 50 kDa membrane when BSA solutions were used as feed.The authors of this work wish to gratefully acknowledge the financial support from the Spanish Ministry of Science and Innovation through the project CTM2010-20186 and the company MAGNETO Special Anodes B.V. for supplying the Ti-Ir electrode.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC.; Ortega Navarro, EM.; Pérez-Herranz, V. (2016). Application of electric fields to clean ultrafiltration membranes fouled with whey model solutions. Separation and Purification Technology. 159:92-99. https://doi.org/10.1016/j.seppur.2015.12.039S929915

Determination of fouling mechanisms in polymeric ultrafiltration membranes using residual brines from table olive storage wastewaters as feed

[EN] In this work, the fouling mechanisms that dominate the ultrafiltration of residual brines from table olive packing plant wastewaters were investigated. For that purpose, Hermia's models adapted to crossflow filtration, resistance-in-series model and a model combining intermediate blocking and cake formation mechanisms were fitted to the experimental data. Tests were performed with a 5 kDa polyethersulfone membrane at transmembrane pressures between 1 and 3 bar and crossflow velocities between 2.2 and 3.7 m s(-1). Results demonstrated that the resistance-in-series model was the most accurate to predict permeate flux evolution with time. The predominant fouling mechanism was cake formation followed by intermediate blocking/adsorption. The fouling resistances that were determined by means of the resistance in series model were tested using a well-established mathematical model proposed by Mondal and De that also combines both fouling phenomena (intermediate pore blocking and cake formation). Results demonstrated that the predicted resistances are consistent with those determined by Mondal and De's model. (C) 2016 Elsevier Ltd. All rights reserved.The authors of this work wish to gratefully acknowledge the financial support of CDTI (Centre for Industrial Technological Development) depending on the Spanish Ministry of Science and Innovation (INNPRONTA program, ITP-20111020).Carbonell Alcaina, C.; Corbatón Báguena, MJ.; Alvarez Blanco, S.; Bes-Piá, M.; Mendoza Roca, JA.; Pastor Alcañiz, L. (2016). Determination of fouling mechanisms in polymeric ultrafiltration membranes using residual brines from table olive storage wastewaters as feed. Journal of Food Engineering. 187:14-23. https://doi.org/10.1016/j.jfoodeng.2016.04.016S142318

Evaluación mediante encuestas al alumnado de la adecuación del uso de simuladores de procesos para mejorar el aprendizaje en ingeniería química

[Otros] Utilization of commercial process simulators in Engineering courses has increased in the last years as a teaching tool for students. In this work, the influence of the commercial simulator CHEMCAD in the learning process of third-year students of Chemical Engineering is evaluated. By means of their responses in surveys, the general satisfaction of students concerning the methodology followed during the practical lessons is determined. The results demonstrates that most of the students agree the fact that CHEMCAD simulator is useful to calculate complex systems in a faster and easier way, to extrapolate results from lab scale to industrial scale and to understand more easily how several equipments from the chemical industries work. Regarding to the methodology, students opinions were divided although most of them consider it adequate[ES] El uso de simuladores comerciales de procesos en diversas asignaturas de Ingeniería ha aumentado considerablemente en los últimos años como refuerzo en la enseñanza de los alumnos. En este trabajo, se evalua la influencia del simulador comercial CHEMCAD en el aprendizaje de los alumnos de tercer curso del Grado en Ingeniería Química. Mediante la respuesta de los alumnos a distintas preguntas formuladas en encuestas se ha determinado la satisfacción general de los mismos respecto a la metodología seguida durante la realización de las clases prácticas. Los resultados indican que la mayoría de los alumnos destacan la utilidad del simulador CHEMCAD para realizar cálculos de sistemas complejos de una manera más rápida y sencilla, para extrapolar sistemas de escala laboratorio a escala industrial y para comprender más fácilmente el funcionamiento de distintos equipos propios de la industria química. En cuanto a la metodología, existe una mayor división de opiniones entre el alumnado, aunque la mayoría la considera adecuada.Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC.; Lloret, J. (2014). Evaluación mediante encuestas al alumnado de la adecuación del uso de simuladores de procesos para mejorar el aprendizaje en ingeniería química. Editorial Universitat Politècnica de València. 1065-1073. http://hdl.handle.net/10251/167121S1065107

Comparison between artificial neural networks and Hermia's models to assess ultrafiltration performance

In this work, flux decline during crossflow ultrafiltration of macromolecules with ceramic membranes has been modeled using artificial neural networks. The artificial neural network tested was the multilayer perceptron. Operating parameters (transmembrane pressure, crossflow velocity and time) and dynamic fouling were used as inputs to predict the permeate flux. Several pretreatments of the experimental data and the optimal selection of the parameters of the neural networks were studied to improve the fitting accuracy. The fitting accuracy obtained with artificial neural networks was compared with Hermia pore blocking models adapted to crossflow ultrafiltration. The artificial neural networks generate simulations whose performance was comparable to that of Hermia's models adapted to crossflow ultrafiltration. Considering the computational speed, high accuracy and the ease of the artificial neural networks methodology, they are a competitive, powerful and fast alternative for dynamic crossflow ultrafiltration modeling.The Spanish Ministry for Science and Innovation (Project OPTIMEM CTM2010-20248) is kindly acknowledged.Corbatón Báguena, MJ.; Vincent Vela, MC.; Gozálvez-Zafrilla, JM.; Alvarez Blanco, S.; Lora-García, J.; Catalán Martínez, D. (2016). Comparison between artificial neural networks and Hermia's models to assess ultrafiltration performance. Separation and Purification Technology. 170:434-444. https://doi.org/10.1016/j.seppur.2016.07.007S43444417

Salt cleaning of ultrafiltration membranes fouled by whey model solutions

In this work, three ultrafiltration (UF) membranes were fouled with whey model solutions that contained BSA (1% w/w) and CaCl2 (0.06% w/w). These membranes were cleaned with NaCl solutions. Temperature, crossflow velocity and concentration were varied. The membranes considered were a polyethersulfone (PES) membrane, a ceramic ZrO2–TiO2 membrane and a permanently hydrophilic polyethersulfone (PESH) membrane. Their molecular weight cut-offs (MWCOs) are 5, 15 and 30 kDa, respectively. The cleaning efficiency was related to the MWCO, membrane material and operating conditions. The results obtained demonstrated that NaCl solutions were able to clean the membranes tested. In addition, the higher the temperature and the crossflow velocity of the cleaning solution, the higher the cleaning efficiency was. However, there was an optimum value of NaCl concentration to clean the membranes effectively. When concentration was higher than the optimum, the cleaning efficiency decreased. The relationship between the cleaning efficiency and the operating conditions was obtained with statistical and optimization analysis.The authors of this work wish to gratefully acknowledge the financial support from the Spanish Ministry of Science and Innovation through the project CTM2010-20186 and the Generalitat Valenciana through the program "Ayudas para la realizacion de proyectos I+D para grupos de investigacion emergentes GV/2013".Corbatón Báguena, MJ.; Alvarez Blanco, S.; Vincent Vela, MC. (2014). Salt cleaning of ultrafiltration membranes fouled by whey model solutions. Separation and Purification Technology. 132:226-233. https://doi.org/10.1016/j.seppur.2014.05.029S22623313