Low porosity, high areal-capacity Prussian blue analogue electrodes enhance salt removal and thermodynamic efficiency in symmetric Faradaic deionization with automated fluid control

•New colloid-inspired fabrication with calendering improved electrode utilization.•FDI system used automatic water recirculation with calibrated valve timing.•Water recirculation with dense electrodes improved salt removal.•System removed 90% of salt from 100 mM NaCl brackish water.•System can remov...

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Bibliographic Details
Published in:Water research X 2021-12, Vol.13, p.100116-100116, Article 100116
Main Authors: Reale, Erik R., Regenwetter, Lyle, Agrawal, Adreet, Dardón, Brian, Dicola, Nicholas, Sanagala, Sathvik, Smith, Kyle C.
Format: Article
Language:English
Subjects:
Colloids
Desalination
Faradaic deionization
Thermodynamic energy efficiency
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Summary:•New colloid-inspired fabrication with calendering improved electrode utilization.•FDI system used automatic water recirculation with calibrated valve timing.•Water recirculation with dense electrodes improved salt removal.•System removed 90% of salt from 100 mM NaCl brackish water.•System can remove 80% of salt with thermodynamic energy efficiency of 80%. Prussian blue analogues (PBAs) show great potential for low-energy Faradaic deionization (FDI) with reversible Na-ion capacity approaching 5 M in the solid-state. However, past continuous-flow demonstrations using PBAs in FDI were unable to desalinate brackish water to potable levels using single-pass architectures. Here, we show that recirculation of effluent from a symmetric cation intercalation desalination cell into brine/diluate reservoirs enables salt removal exceeding 80% at thermodynamic efficiency as high as 80% when cycled with 100 mM NaCl influent and when controlled by a low-volume, automated fluid circuit. This exceptional performance is achieved using a novel heated, alkaline wet phase inversion process that modulates colloidal forces to increase carbon black aggregation within electrode slurries to solidify crack-free, high areal-capacity PBA electrodes that are calendered to minimize cell impedance and electrode porosity. The results obtained demonstrate the need for co-design of auxiliary fluid-control systems together with electrode materials to advance FDI beyond brackish salinity.
ISSN:2589-9147
2589-9147
DOI:10.1016/j.wroa.2021.100116