title: Effect of Solution Composition on the Energy Production by Capacitive Mixing in Membrane-Electrode Assembly.
abstract: In this work, we consider the extent to which the presence of multivalent ions in solution modifies the equilibrium and dynamics of the energy production in a capacitive cell built with ion-exchange membranes in contact with high surface area electrodes. The cell potential in open circuit (OCV) is controlled by the difference between both membrane potentials, simulated as constant volume charge regions. A theoretical model is elaborated for steady state OCV, first in the case of monovalent solutions, as a reference. This is compared to the results in multi-ionic systems, containing divalent cations in concentrations similar to those in real seawater. It is found that the OCV is reduced by about 25% (as compared to the results in pure NaCl solutions) due to the presence of the divalent ions, even in low concentrations. Interestingly, this can be related to the "uphill" transport of such ions against their concentration gradients. On the contrary, their effect on the dynamics of the cell potential is negligible in the case of highly charged membranes. The comparison between model predictions and experimental results shows a very satisfactory agreement, and gives clues for the practical application of these recently introduced energy production methods.
authors.affiliation: Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ahualli
authors.affiliation: Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain.
authors.forename: M Mar
authors.initials: MM
authors.lastname: Fernández
authors.affiliation: Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Iglesias
authors.affiliation: Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain.
authors.forename: María L
authors.initials: ML
authors.lastname: Jiménez
authors.affiliation: WETSUS, Centre of Excellence for Sustainable Water Technology , 8900 CC, Leeuwarden, The Netherlands.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: WETSUS, Centre of Excellence for Sustainable Water Technology , 8900 CC, Leeuwarden, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Wagterveld
authors.affiliation: Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain.
authors.forename: Angel V
authors.initials: AV
authors.lastname: Delgado
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