Effect of Turbulence on Limiting Current in Electrodialysis Cells

Organic acids are increasingly used for various industrial applications. Their production is mainly achieved by fermentation. Precipitation or extraction stages, which generate big amount of effluents, are then traditionally used to get the acid in a suitable form. To lower the impact on the environment, the implementation of cleaner operations are investigated. In this context, a complete process targeted around membrane operations for clarification, concentration and conversion was studied. The present paper is devoted to the study of the concentration step, carried out by conventional electrodialysis (EDC). A model, based on the description of the solute and solution fluxes through the membranes is developed. Dedicated procedures are proposed to determine the different contributions, i.e. electromigration and diffusion, to these fluxes so as to feed the model. This approach is then applied to the concentration of sodium lactate solutions. The preponderance of electromigration is thus demonstrated as well as the existence of a maximum achievable concentration, the predicted value of which is confirmed experimentally. Comparison between EDC of sodium and ammonium lactate solutions shows that the counter ion has negligible influence on the transport of lactate. The influence of the membrane characteristics is also drawn from comparison with previously published results. Finally, the predictions of the model are compared with the experimental results concerning the concentration of a fermentation broth and a good agreement is stated. The approach proposed in this paper can be used as well to design EDC concentration of any other organic acid salt than lactate.

Section: Experimental Procedures and Operating Conditionsmentioning

confidence: 99%

Production processes of fermented organic acids targeted around membrane operations: design of the concentration step by conventional electrodialysis

Bailly

2001

“…Moreover, it is usually accompanied by the generation of acidic effluents as a consequence of the increased exposed area of sulfur-bearing rocks during mining. This phenomenon allows for an excess of acid generation beyond the natural buffering capabilities found in host rock and water resources, thus aggravating the impacts of mining on aquatic ecosystems [18]. Among those impacts are included the Chapter 1.…”

Section: Introductionmentioning

confidence: 99%

Determination of transport properties of Ni(II) through a Nafion cation-exchange membrane in chromic acid solutions

Martí-Calatayud

García-Gabaldón

Pérez-Herranz

et al. 2011

Acknowledgements / Agradecimientos / AgraïmentsEn primer lugar quisiera agradecer a Valentín y a Montse por haberme dado la oportunidad de investigar con ellos, por introducirme en un mundo que me ha fascinado, por haberme dirigido, por haberme ayudado en momentos de desasosiego; porque, en definitiva, creo que hemos formado un gran equipo.Quisiera agradecer a la Universitat Politècnica de València la financiación recibida para realizar la tesis. En general, he de agradecer al sistema de educación pública que ha permitido que un hijo de trabajadores como yo haya podido llegar hasta aquí. Además, quiero aprovechar para exigir un sistema de educación público, de calidad, e igualitario, que forme a personas con espíritu crítico y libre; puesto que sólo así se conseguirá que progresemos como sociedad.I would also like to thank to all the people from the group of Chemical Process Engineering of the RWTH Aachen University, especially to Matthias Wessling and Said Abdu, for accepting me in their research group. They have been very kind to me and I have learnt a lot from them and from this fruitful and unforgettable experience in Aachen.También quisiera agradecer a Daniella Buzzi por haberme dejado ser su "chefinho", por tantos momentos buenos y algún que otro momento crítico vividos juntos, porque es bonito saber que tengo una gran amiga al otro lado del charco.Gracias al Grupo IEC, en especial a mis compañeros, con los que he pasado más momentos juntos. Ellos han sido mi familia investigadora. Gracias a Isaac y Carlos, porque han sido para mí un referente, a Jordi y Ramón, porque han estado desde el principio, han sido como mis hermanos, y a Vir y Tepe, ellas han contribuido a que haya un ambiente de trabajo inmejorable! Quiero también dar las gracias al resto de componentes del grupo por su ayuda, en especial a Emma Ortega, a José Luis Guiñón por su ayuda con los equilibrios, y a Anna Igual porque con su energía consigue contagiar su pasión por la investigación.El fruto del trabajo de todos estos años tampoco sería posible sin los momentos vividos junto a mis amigos, el "Kanchy". Ellos son "los de toda la vida", los que siempre han estado, están y estarán ahí. Quisiera hacer mención especial a Lidia por su ayuda con la Tesis, y cómo no, a Sergio, porque juntos hemos arreglado el mundo un millón de veces… ¡para volverlo a destrozar otras tantas! No quiero olvidarme de ninguna de las personas con las que he coincidido y he pasado buenos momentos tanto en Valencia, como en Berlín o en Aachen… Maite, Laura, Guillaume… es imposible nombrarlos a todos… pero quiero agradecer en especial a Tania, porque con ella no existe el tiempo ni la distancia, sé que siempre está ahí a mi lado.Ha arribat el moment d'agrair a les quimixiques els grans moments viscuts. Amb elles hem format una gran família. Em sent molt afortunat d'haver caigut en un grup tan de "puça mare": gràcies a les Silvies, Elena, Gabriel·la, Angeleta, Rosa de Xeraco, Alicia, i en especial a Susana, la meua companya de batalles, i a Ingrid, una gran amiga.Per últim...

“…To complete the characterization of the reactor it is necessary to know the limiting current density (j lim ) [5,[22][23][24][25][26][27][28]. To this aim, polarization curves at different conductivity of the solutions were carried out.…”

Section: Determination Of Limiting Current Densitymentioning

confidence: 99%

“…The chosen conductivities for plotting the polarization curves were: the initial value, 9 mS cm The limiting current density can be determined by plotting V/I vs. 1/I [5,28]. The appearance of the limiting current density is a phenomenon of the individual membranes, caused by the concentration polarization.…”

Section: Determination Of Limiting Current Densitymentioning

confidence: 99%

Application of electrodialysis for the treatment of almond industry wastewater

Valero

García-García

Expósito

et al. 2015

In this work, electrodialysis has been proved to be a suitable technique for decreasing the conductivity of a real wastewater from an almond industry, which has been previously treated by electrocoagulation (EC) and electrooxidation (EO). A seven-cell electrodialyzer, with total active membrane area of 1400 cm 2 , was employed and several parameters, as the limiting current density, were determined. A method for measuring voltage across the membranes was developed, in order to control membrane fouling. The method consisted of capillaries inserted into the solution compartments and connected to a high impedance voltmeter. A study of the reuse of the concentrate solution was made, and it was stated that it can be concentrated ten times. The treatment of the wastewater was performed at different voltages (7-16 V) to reach values of conductivity of the diluate of 0.5 mS cm -1 . After that, the scaling up to a pre-industrial scale was performed by using a seventy-cell electrodialyzer, with total active membrane area of 3.5 m 2 . The process was performed by applying voltages of 20-70 V and a final conductivity of the diluate of 0.5 mS cm -1 was achieved. The electric energy consumption was calculated in every case.2