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Khiter_et_al April 2020.pdf (541.16 kB)
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Behavior of Volatile Compounds in Membrane Distillation: The Case of Carboxylic Acids

preprint
submitted on 22.04.2020 and posted on 24.04.2020 by Abdelaziz Khiter, Béatrice Balannec, Anthony Szymczyk, Omar Arous, Noureddine Nasrallah, Patrick LOULERGUE

Thanks to its unique features, membrane distillation (MD) has been particularly applied for desalination but also for niches applications with feed solutions containing a mixture of volatile molecules. For such solutions, the complex interplay of the solutes and solvent physicochemical and operating parameters makes it challenging to predict the separation efficiency by MD. There is thus a need for a better understanding of the behavior of volatile compounds in MD as well as the influence of their physicochemical environment. This study aimed at investigating the influence of different operating parameters on rejection efficiency of air-gap MD towards carboxylic acids (formic, acetic and succinic acids). Acid rejection was found to be highly dependent on the carboxylic acid structure. In addition, it increased with the acid concentration, which could be related to the formation of acid dimers in the feed solution. This behavior is opposite to what is classically observed for pressure-driven membrane processes thus suggesting that MD can be a suitable alternative to these techniques for the concentration/separation of carboxylic acids. On the other hand, acid rejection decreased with the increase of feed temperature which could be explained by the calculation of the apparent energies of activation of both the water and carboxylic acids using an Arrhenius-type model. Finally, the acid dissociation rate played a key role in the acid rejection. Taking advantage of this observation, it was demonstrated how a simple pH adjustment can be used to successfully achieve the selective separation of ethanol (compared to acetic acid) from an acetic acid/ethanol aqueous mixture (typical case of the extraction of bioethanol from a fermentation broth).

Funding

Ministère de l'enseignement supérieure et de la recherche scientifique Algérienne, direction de la coopération et des échanges inter-universitaires (Grant 378/PNE/FRANCE/2016/2017)

History

Email Address of Submitting Author

Patrick.loulergue.1@univ-rennes1.fr

Institution

Univ Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, France

Country

France

ORCID For Submitting Author

0000-0003-3121-5533

Declaration of Conflict of Interest

none

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