ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of limiting current density for different electrodialysis modules

Natália Káňavová, Lubomír Machuča, and David Tvrzník

MemBrain s.r.o., Pod Vinicí 87, 471 27, Stráž pod Ralskem, Czech Republic

E-mail: Natalia.Kanavova@membrain.cz

Abstract: Limiting current density of ammonium nitrate solution in laboratory-, pilot-, and industrial-scale electrodialysis modules were determined to provide a method for the prediction of the limiting current density of ammonium nitrate solutions at any conditions. The current-voltage curve was measured in each case and the limiting current density was evaluated using the dependence of the derivative, dI/dU, on the electric current, I. The limiting current was determined as a current at which the derivative dI/dU equals zero. The developed method enables not only the prediction of the limiting current density but the limiting cut and limiting flux can be determined concurrently at any linear flow velocity of the diluate and inlet ammonium nitrate concentration. It could help to prevent working in the overlimiting region and to avoid undesirable decrease of current efficiency and pH changes. The limiting cut is the maximal cut that can be obtained at certain linear flow velocity and module geometry irrespective of the inlet ammonium nitrate concentration and it is very useful information when designing a new electrodialysis unit for specific application.

Keywords: desalination – electrodialysis – ion exchange membrane – current-voltage curve – limiting current density

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0456-z

Chemical Papers 68 (3) 324–329 (2014)