Abstract
Flow-electrode capacitive deionization (FCDI) can be improved via enhanced charge transfer by increasing the flow-electrode (FE) conductivity. Since water is the main component of FE (>70%), the key to improving the electroconductivity lies in the properties of carbon materials. In this work, three types of carbon powders, i.e., activated carbon (AC), mesoporous carbon, and carbon nanotubes (CNTs), were employed in FEs to investigate the influence of powder properties on the FCDI performance. The morphology and structure of powders and electrochemical behavior and rheology of FEs were investigated to reveal the relationship between FE properties and desalination performance. Results show that, due to their unique electrosorption behavior, excellent conductivity, and enhanced conductivity through a bridging effect, CNT-based FE (carbon loading: 3 wt %) achieved the fastest (8.3 mg s-1 m-2) and the most stable desalination (charge efficiency: 93.3%). A faster desalination (13.2 mg s-1 m-2), due to significantly improved electroconductivity (13.2 times) with only a slight viscosity increase (1.1 times), was achieved by adding CNTs into 6.91 wt % AC-based FE for a 7.41 wt % total carbon concentration. This study highlights the importance of the intrinsic properties of carbon materials, especially electroconductivity, in promoting FCDI desalination performance.
| Original language | English |
|---|---|
| Pages (from-to) | 1085-1094 |
| Number of pages | 10 |
| Journal | ACS Sustainable Chemistry and Engineering |
| Volume | 7 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 7 2019 |
Funding
This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/ downloads/doe-public-access-plan). The authors would like to thank the School of Civil and Environmental Engineering of the Georgia Institute of Technology and the National Natural Science Foundation of China (NSFC) for financial support via Grants 51425405 and 21377130. K.T. appreciates financial support from China Scholarship Council (CSC, 201606250079). C.T. acknowledges support from the Laboratory Directed Research and Development Program of the Oak Ridge National Laboratory. The authors thank Alexander Wiechert for editing the manuscript.
| Funders | Funder number |
|---|---|
| School of Civil and Environmental Engineering | |
| Oak Ridge National Laboratory | |
| Georgia Institute of Technology | |
| National Natural Science Foundation of China | 51425405, 21377130 |
| China Scholarship Council | 201606250079 |
Keywords
- Carbon nanotubes
- Charge/ion transfer
- Desalination
- Electrochemical impedance spectroscopy
- Flow-electrode capacitive deionization
