US 12,662,401 B2
Hybrid electrodialysis and electrolysis systems and processes
Joun Lee, Coralville, IA (US); and Timothy Alan Young, Santa Barbara, CA (US)
Assigned to PANI CLEAN, INC., Coralville, IA (US)
Filed by PANI CLEAN, INC., Coralville, IA (US); and University of Iowa Research Foundation, Iowa City, IA (US)
Filed on Jun. 11, 2021, as Appl. No. 17/345,982.
Claims priority of provisional application 63/038,625, filed on Jun. 12, 2020.
Prior Publication US 2021/0387874 A1, Dec. 16, 2021
Int. Cl. C02F 1/469 (2023.01); B01D 61/42 (2006.01); B01D 61/46 (2006.01); B01D 61/52 (2006.01); C02F 1/461 (2023.01); C02F 1/467 (2023.01); C02F 101/16 (2006.01); C02F 103/00 (2006.01)
CPC C02F 1/4693 (2013.01) [B01D 61/422 (2013.01); B01D 61/463 (2022.08); B01D 61/52 (2013.01); C02F 1/46109 (2013.01); C02F 1/4676 (2013.01); B01D 2311/2684 (2013.01); B01D 2313/345 (2013.01); C02F 2001/46142 (2013.01); C02F 2101/163 (2013.01); C02F 2103/001 (2013.01); C02F 2201/46115 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A method of removing and electro-reducing nitrate anion from a feedwater comprising nitrate solutes, the method comprising:
providing an integrated electrodialysis and electrolysis hybrid system that includes
a first electrode,
a second electrode disposed opposite the first electrode, and
an anion exchange membrane adjacent to the first electrode and a cation exchange membrane adjacent to the second electrode and between the first and second electrodes to define (i) a feedwater compartment between the respective membranes, (ii) an anion concentration compartment adjacent to the anion exchange membrane, said anion exchange membrane and first electrode defining the anion concentration compartment therebetween, and (iii) a cation concentration compartment adjacent to the cation exchange membrane, said cation exchange membrane and second electrode defining the cation concentration compartment therebetween, and
wherein said first electrode is comprised of a planar electrically conductive material capable of operating as an electrodialysis electrode when operated as an anode and as a catalytically electro-reductive electrode capable of selectively electro-reducing nitrate anion transferred from the feedwater when operated as a cathode; and
wherein said first electrode is the only electrode adjacent to or in direct contact with the anion concentration compartment;
passing the feedwater into the feedwater compartment and providing water to the anion and the cation concentration compartments, and
operating the hybrid system for a first time period in an electrodialysis mode by imposing an anodic polarity across the first electrode and a cathodic polarity across the second electrode to produce a concentration of nitrate ion in the feedwater compartment that is lower than the incoming feedwater, and producing a water in the anion concentration compartment that includes the nitrate anions passing through the anion exchange membrane and
operating the hybrid system, for a second time period, in an electrolysis mode by reversing the polarity across the first and second electrodes, such that the first electrode becomes cathodic with respect to the second electrode, and whereby the nitrate in the anion concentration compartment is electro-reduced such that the Faradaic efficiency for conversion of nitrate to nitrite is higher than the Faradaic efficiency for conversion of nitrate to nitrogen gas.