Clarkson University
Department of Chemical and Biomolecular Engineering
SEMINAR (ZOOM)
Gowri Mohandass (Ph.D. Candidate, Clarkson University) will speak on:
“Fe(III)/Fe(II) Redox Flow Batteries for Brackish Water Desalination”
Redox Flow batteries (RFBs) can store a large amount of electrical energy by reducing the anode electrolyte and oxidizing the cathode electrolyte, separated by an ion-exchange membrane. By introducing additional channels, in between the anolyte and catholyte, for the flow of saltwater, RFBs can perform both desalination and energy storage. We have developed redox flow batteries based on aqueous, near-neutral-pH electrolytes suitable for freshwater production from brackish water. Iron citrate catholyte and iron cyanide anolyte were incorporated in a four-channel asymmetric RFB with aqueous NaCl feed solutions (3 g/L) in the middle channels. Upon the application of current in a continuous flow process, the RFB simultaneously stored energy in the redox electrolytes and produced freshwater with NaCl concentration below 0.5 g/L. A separate two-channel RFB was used to extract the energy stored in the redox electrolytes. A peak power density of 6 mW/cm2 was achieved. The cell voltage utilized to desalinate the feed solution was minimized in a symmetric RFB with iron citrate as both catholyte and anolyte. At throughput productivity of 41.1 LMH (L-freshwater per m2-membrane area per h-operation time) and water recovery (desalinated to feed water volume ratio) of 50 %, the symmetric RFB consumed 0.48 kWh/m3 for producing freshwater. For a slightly higher energy input of 0.56 kWh/m3, a significantly higher water recovery of 91 % could be achieved, which reduces the volume of brine to facilitate its disposal or valorization. In comparison with some previous studies, the symmetric RFB produced freshwater at around three times the productivity for the same energy demand. The symmetric RFB substantially reduced the cell potential (0.4 V) relative to that needed in a single-cell-pair electrodialysis system driven by water electrolysis (3.4 V). This low voltage requirement of the symmetric RFB is ideally suitable for using single junction silicon solar cells with a typical open circuit voltage of 0.5–0.7 V. The RFB system could be the sustainable path for energy conversion, storage and brackish water desalination.
Wednesday, September 28th, 2022 at 3:00 pm
