Data underlying the publication: Water content of ion-exchange membranes: Measurement technique and influence on the ion mobility
Authors: Alaaeldin A.E. Elozeiri (a), Rob G.H. Lammertink (b), Huub H.M. Rijnaarts (a), Jouke E. Dykstra (a, *)
(a) Environmental Technology, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, the Netherlands
(b) Membrane Science and Technology, Faculty of Science and Technology (TNW), University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
(*) Corresponding author. E-mail address: jouke.dykstra@wur.nl



Description:

This dataset was collected at the Laboratory of Environmental Technology, Wageningen University & Research in 2023/2024. It is supplementary data for the PhD thesis of Alaaeldin Elozeiri and the publication of "Water content of ion-exchange membranes: Measurement technique and influence on the ion mobility. We studied the following properties of commercial cation-exchange membranes: the membrane water content, the membrane water volume fraction, the membrane resistance, the ion-exchange capacity, the membrane thickness, the ionic charge density, and the ion mobility inside the membrane.

This research was performed within the framework of the research program AquaConnect, funded by the Dutch Research Council (NWO, grant-ID P19-45) and public and private partners of the AquaConnect consortium and coordinated by Wageningen University and Research.

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File (water_content):
Sheet (WC_Method_A_B_C_D): It contains the water content measurements for single membrane sheets equilibrated at 0.5 M NaCl where the surface water film was removed via methods: (A) Shaking the membrane in air three times (B) Drying membrane surface with a thick tissue (thickness 160 ?m) (C) Drying membrane surface with a thin tissue (thickness 100 ?m, lower absorption capacity) (D) Drying membrane surface with a dry paper (thickness 103 ?m)

Sheet (WC_stacking): It contains the water content measurements via the stacking technique at different electrolyte solutions. M_dry_T: total dry membrane mass in the stack where the mass is corrected for the corresponding counter-ion form. Ms_wet_T: total wet mass of the stack.

Sheet (dry-wet_swelling): It contains the dry and wet (at 0.5 M NaCl) membrane dimensions used to calculate the membrane swelling along its length

Sheet (dry_mass): It contains the measured dry membrane mass after different drying steps.

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File (exchange):
It contains the exchange percentage of the counter-ions inside the membrane from one species to another.
	
Sheet (Na+ to K+): Exchange of the counter-ions in samples of commercial ion-exchange membranes from Na+ to K+ by submerging the samples in a 200 mM KCl solution for a total duration of 2.5 h. The exchange solution was refreshed twice, i.e. three exchange steps. We analyzed the overall exchange solution as well as the solution of each exchange step.

Sheet (K+ to Mg2+): Exchange of the counter-ions in samples of commercial ion-exchange membranes from K+ to Mg2+ by submerging the samples in a 100 mM MgCl2 solution for a total duration of 3 h. The exchange solution was refreshed twice, i.e. three exchange steps. We analyzed the overall exchange solution as well as the solution of each exchange step.

Sheet (Mg2+ to Ca2+): Exchange of the counter-ions in samples of commercial ion-exchange membranes from Mg2+ to Ca2+ by submerging the samples in a 10 mM CaCl2 solution for a total duration of 3 h. The exchange solution was refreshed twice, i.e. three exchange steps. We analyzed the overall exchange solution as well as the solution of each exchange step.

Sheet (Ca2+ to H+): Exchange of the counter-ions in samples of commercial ion-exchange membranes from Ca2+ to H+ by submerging the samples in a 1 M HCl solution for a total duration of 18 h. The exchange solution was refreshed once after 17 h. We analyzed the overall exchange solution.

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File (DC):
It contains the current-voltage response of different membranes at 0.5 M NaCl as measured via linear potential sweep (direct current) using a 6-compartment electrodialysis cell. The active membrane area was 5.4  0.1 cm2. The solutions were recirculated at 0.25  0.3 L/min through the cell and heat exchangers to keep the temperature at 20 ?C (1).

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File (EIS):
It contains the real (Z1) and imaginary (Z2) impedance of different membranes at 0.5 M NaCl(and a blank) as measured via electrochemical impedance spectroscopy (EIS) using a 6-compartment electrodialysis cell at 0.5 M NaCl. The active membrane area was 5.4  0.1 cm2. The solutions were recirculated at 0.25  0.3 L/min through the cell and heat exchangers to keep the temperature at 20 ?C (1). Sine waves of amplitude 10 mA at open circuit voltage were applied to scan the frequencies from 1E+5 to 1E-1 Hz.
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