Comparing Intercalation Electrodes for Energy Efficient Brackish Water Desalination
Open Access
- Author:
- Pothanamkandathil, Vineeth
- Graduate Program:
- Environmental Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 16, 2019
- Committee Members:
- Christopher A Gorski, Thesis Advisor/Co-Advisor
Bruce Logan, Committee Member
Fred Scott Cannon, Committee Member
Patrick Joseph Fox, Program Head/Chair - Keywords:
- Electrochemical Desalination
Intercalation Electrodes
Energy Demand
Desalination Rate
Electrode Stability - Abstract:
- One approach for desalinating brackish water is to use electrode materials that electrochemically remove salt ions from water. Recent studies found that sodium-intercalating electrode materials (i.e., materials that reversibly insert Na+ ions into their structures) have higher salt storage capacities (mg·g-1) than carbon-based capacitive electrode materials. These observations have led to the hypothesis that the energy demands of electrochemical deionization systems can be decreased by replacing capacitive electrodes with intercalating electrodes. To test this hypothesis quantitatively and directly compare different intercalation materials, we examined several sodium-intercalation electrode materials in an electrochemical flow cell with respect to their volumetric energy demands (W·h·L–1) and thermodynamic efficiencies as a function of productivity (i.e., the rate of water desalination, L·m-2·h-1). We also examined how the materials’ charge storage capacities declined over repeated cycles. Intercalation materials deionized brackish water more efficiently than capacitive carbon-based electrodes when we assumed no energy recovery occurred (i.e., no energy was recovered when the cell had a positive voltage during cycling) and exhibited similar efficiencies when we did assume complete energy recovery. Nickel hexacyanoferrate exhibited the lowest energy demand among all the materials and exhibited good stability over 50 cycles.