Divalent Ion Selectivity in Capacitive Deionization with Vanadium Hexacyanoferrate: Experiments and Quantum-Chemical Computations

Singh, Kaustub, Li, Guanna, Lee, Juhan ORCID: 0000-0001-5036-3449, Zuilhof, Han, Mehdi, Beata L ORCID: 0000-0002-8281-9524, Zornitta, Rafael L and de Smet, Louis CPM (2021) Divalent Ion Selectivity in Capacitive Deionization with Vanadium Hexacyanoferrate: Experiments and Quantum-Chemical Computations. ADVANCED FUNCTIONAL MATERIALS, 31 (41). p. 2105203.

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Official URL: http://dx.doi.org/10.1002/adfm.202105203

Abstract

<jats:title>Abstract</jats:title><jats:p>Selective removal of ions from water via capacitive deionization (CDI) is relevant for environmental and industrial applications like water purification, softening, and resource recovery. Prussian blue analogs (PBAs) are proposed as an electrode material for selectively removing cations from water, based on their size. So far, PBAs used in CDI are selective toward monovalent ions. Here, vanadium hexacyanoferrate (VHCF), a PBA, is introduced as a new electrode material in a hybrid CDI setup to selectively remove divalent cations from water. These electrodes prefer divalent Ca<jats:sup>2+ </jats:sup>over monovalent Na<jats:sup>+</jats:sup>, with a separation factor, β<jats:sub>Ca/Na </jats:sub>≈3.5. This finding contrasts with the observed monovalent ion selectivity by PBA electrodes. This opposite behavior is understood by density functional theory simulations. Furthermore, coating the VHCF electrodes with a conducting polymer (poly‐pyrrole, doped with poly‐styrenesulphonate) prevents the contamination of the treated water following the degradation of the electrode. This facile and modular coating method can be effortlessly extended to other PBA electrodes, limiting the extent of treated water contamination during repeated cycling. This study paves the way for tunable selectivity while extending the library of electrodes that can be successfully used in (selective) CDI.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	capacitive deionization, density functional theory, intercalation, ion selectivity, Prussian blue analogs, simulations
Divisions:	Faculty of Science and Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	20 Dec 2021 15:16
Last Modified:	04 Sep 2023 10:19
DOI:	10.1002/adfm.202105203
Open Access URL:	https://onlinelibrary.wiley.com/doi/10.1002/adfm.2...
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3145699