Revealing intrinsic differences between static and flow electrode capacitive deionization by introducing semi-flow electrodes
Flow electrode capacitive deionization (FCDI) was an emerging technology because of its distinctive benefits. However, understanding for effects of electrode mobility was limited. In this study, we designed semi-flow electrode mode as an intermediate state between static and flow electrode mode. The advantages of FCDI were revealed since it could be considered as extreme condition of semi-flow mode with infinite time interval and full volume replacement. It was demonstrated by semi-flow electrode mode that deionization capacity was directly and proportionally recovered. Higher volume of fresh carbon slurry accounted for higher adsorption capacity as well as lower energy consumption. Timely regeneration of FCDI electrode slurry enhanced salt adsorption rate (3 times) and reduced specific energy consumption (4.5±0.2 J/mg Na in FCDI while 7.0±1.4 J/mg Na in semi-flow electrode and 7.6±0.8 J/mg Na in static mode) in deionization condition of this study (500 mg Na/L, 1.2 V, 5 wt%). This research provided insights into fundamental understanding for FCDI technology, enhancing its performance via timely regeneration of the electrode materials and maintaining system in high efficiency deionization state.
- This article is part of the themed collection: Capacitive Deionisation 2020