Assembly of Soft Electrodes and Ion Exchange Membranes for Capacitive Deionization
Metadatos
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Ahualli Yapur, Silvia Alejandra; Orozco Barrera, Sergio; Fernández, María del Mar; Delgado Mora, Ángel Vicente; Iglesias Salto, Guillermo RamónEditorial
MDPI
Materia
Capacitive deionization Polyelectrolytes Salt adsorption Soft electrodes Ion exchange membranes
Fecha
2019-09-25Referencia bibliográfica
Ahualli, S., Orozco-Barrera, S., Fernández, M. D. M., Delgado, Á. V., & Iglesias, G. R. (2019). Assembly of Soft Electrodes and Ion Exchange Membranes for Capacitive Deionization. Polymers, 11(10), 1556.
Patrocinador
This research was funded by MINECO, Spain, grant number PGC2018-098770-B-I00 and RYC-2014-16901Resumen
The responsible use of water, as well as its reuse and purification, has been a major problem
for decades now. In this work, we study a method for adsorbing ions from aqueous solutions on
charged interfaces using highly porous electrodes. This water purification process is based on the
electric double layer concept, using the method known as capacitive deionization (CDI): If we pump
salty solutions through the volume comprised between two porous electrodes while applying a
potential difference to them, ions present in the solution are partially removed and trapped on the
electrode surfaces. It has been well established that the use of carbon electrodes in combination with
ion exchange membranes (membrane-CDI) improves the efficiency of the method above that achieved
with bare activated carbon. Another approach that has been tested is based on coating the carbon
with polyelectrolyte layers, converting them into “soft electrodes” (SEs). Here we investigate the
improvement found when combining SEs with membranes, and it is shown that the amount of ions
adsorbed and the ratio between ions removed and electrons transported reach superior values, also
associated with a faster kinetics of the process. The method is applied to the partial desalination of up
to 100 mM NaCl solutions, something hardly achievable with bare or membrane-covered electrodes.
A theoretical model is presented for the ion transport in the presence of both the membrane and the
polyelectrolyte coating.