The energy-water nexus poses an integrated research challenge, while opening up an
opportunity space for the development of energy efficient technologies for water remediation.
Capacitive Deionization (CDI) is an upcoming reclamation technology that uses a small applied
voltage applied across electrodes to electrophoretically remove dissolved ionic
impurities from wastewater streams. Similar to a supercapacitor, the ions are stored in the
electric double layer of the electrodes. Reversing the polarity of applied voltage enables
recovery of the removed ionic impurities, allowing for recycling and reuse. Simultaneous
materials recovery and water reclamation makes CDI energy efficient and resource conservative,
with potential to scale it up for industrial applications. The efficiency of the technology
depends on the architectural design of the CDI cell, control of operating conditions, and the
nature of the electrodes used. In this project we report on the performance of Ti3C2Tx
MXenes flow electrodes in a CDI cell design. MXenes are a novel class of two-dimensional (2D)
transition metal carbides, nitrides and carbonitrides with the general formula Mn+1XnTx
where M is an early transition metal, X is carbon and/or nitrogen, Tx represents the surface
terminations. Ti3C2Tx MXenes synthesized at Boise State, were
employed as a flow electrode solution in an established CDI cell for targeted and selective ion
removal. Performance metrics of achieved adsorption capacity, ion removal efficiency, regeneration
efficiency, energy consumption, and charge efficiency, exceed those of currently prevalent electrode
systems. In addition, rheological properties of the Ti3C2Tx MXenes
colloidal solution were evaluated. This work establishes the deionization performance of
Ti3C2Tx MXene based flow electrodes while providing further insight
towards understanding the effect of structure and surface functionalization on the resultant
deionization efficiency.
Asymmetric electrode capacitive deionization for energy efficient desalination
