Determination of limiting current density and current efficiency in electrodialysis units

Risultato della ricerca: Articlepeer review

35 Citazioni (Scopus)

Abstract

A crucial parameter for the design and operation of electrodialysis (ED) units is the limiting current density (LCD). This is often identified with the diffusion-limited current density, which corresponds to the complete solute depletion in the layer adjacent to the membrane. Current-voltage curves obtained from measurements with electrodes in contact with the solution (i.e. without membranes) are consistent with this interpretation and exhibit a horizontal plateau identifying LCD. However, real ED systems show more complex behaviours, with a reduced-slope tract instead of a plateau and a third region in which the current increases more markedly (overlimiting current). The phenomena involved in the limiting region are not yet totally characterized and the determination of LCD in ED units is still ambiguous. In the present work, we explore the issues related to the identification of LCD, by measurements on ED units, assessing the influence of operating conditions and validating a simplified process simulator. A new method to determine LCD, based on the current efficiency, is proposed and compared with other methods presented in the literature. A second limiting quantity is also identified, i.e. the critical current density, below which diffusion phenomena prevail on migration and a method for its assessment is proposed.
Lingua originaleEnglish
pagine (da-a)138-148
Numero di pagine11
RivistaDESALINATION
Volume445
Stato di pubblicazionePublished - 2018

All Science Journal Classification (ASJC) codes

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  • ???subjectarea.asjc.1500.1500???
  • ???subjectarea.asjc.2500.2500???
  • Water Science and Technology
  • Mechanical Engineering

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