Public Abstract

DE-SC0022237: Electrochemical Hydrogen Isotope Fractionation - Fundamental Insights Leading to Process Scale Up.

Award Status: Inactive

Institution: Vanderbilt University, Nashville, TN
UEI: GTNBNWXJ12D5
PM: Balkin, Ethan

Most Recent Award Date: 09/07/2021
Number of Support Periods: 1
PI: Kidambi, Piran Ravichandran

Current Budget Period: 08/01/2021 - 06/30/2023
Current Project Period: 08/01/2021 - 06/30/2023

Public Abstract

Electrochemical hydrogen isotope fractionation - fundamental insights leading to process scale up Steve Xiao, Savannah River National Laboratory (Principal Investigator) Stephen Creager, Clemson University (Co-Investigator) Piran R Kidambi, Vanderbilt University (Co-Investigator) Project Summary The project will have impact through the scientific knowledge that will be gained from the project work and also through improvements that may be enabled for cost-effective production and recycling of deuterium and tritium isotopes. Tritium is used as a radiolabel in drug binding and pharmacology research, as an autoradiography label in medical imaging, and in emerging self-powered lighting and betavoltaic battery applications. Applications in cost-effective removal of tritium from natural waters and from nuclear reactor process waters are also needed and could be enabled by this research. We propose research on hydrogen isotope separation using graphene in the Membrane Electrode Assemblies (MEAs) of Proton Exchange Membrane (PEM) electrochemical hydrogen pump cells to address technical challenges leading to practical implementation of this process. The study will investigate quantum understanding of H/D/T selectivity, characterize the large-area graphene membranes and solve isotope transport issues that can enable scale-up of separation processes. In a recent study, the Clemson/SRNL team surpassed prior results at 14:1 H/D selectivity, and also demonstrated a 5000X increased proton flux using an improved cell design. The H/T selectivity was predicted to be higher at 59:1 but needs to be experimentally verified. An elegant method to scale-up the water isotope separation process has been proposed using PEM hydrogen pumping through a 2-D membrane in a counter-current flow in a circulation loop. Studies on H/D/T selectivity help to understand the isotope sieving mechanism in which a quantum tunneling hypothesis explains well that the isotope selectivity is independent of the type of membrane (e.g., graphene vs hBN). This proposal focuses on developing fundamental insights that would eventually lead to scale-up and allow efficient staged membrane separations. The project is a collaboration among Savannah River National Lab, Clemson University and Vanderbilt University. Studies on tritium will be pursued at SRNL using graphene-containing electrochemical cells from Clemson with graphene from Vanderbilt University. SRNL will also develop a quantum tunneling mechanism on the isotopic sieving and start investigation to identify key technical needs for process scale up. Development of PEM-style electrochemical hydrogen pump cells with graphene included in the MEA will be pursued at Clemson. Clemson will also investigate mass transport in MEA cells that would eventually enable process scale-up with the circulation loop concept. Vanderbilt will develop and fabricate monolayer graphene and graphene/polycarbonate assembly to characterize the graphene lattice over centimeter-scale and probe the influence of diffusive transport on H/D selectivity in liquid state. The principal project objective will be to test the following hypothesis: “Hydrogen isotope selectivity increased by graphene in a proton-exchange membrane (PEM) electrolysis cell is the result of quantum tunneling due to mass differences of H/D/T and how this selectivity can be maintained during scale-up.”

Electrochemical hydrogen isotope fractionation - fundamental insights leading to process scale up

Steve Xiao, Savannah River National Laboratory (Principal Investigator)

Stephen Creager, Clemson University (Co-Investigator)

Piran R Kidambi, Vanderbilt University (Co-Investigator)

Project Summary

The project will have impact through the scientific knowledge that will be gained from the project work and also through improvements that may be enabled for cost-effective production and recycling of deuterium and tritium isotopes. Tritium is used as a radiolabel in drug binding and pharmacology research, as an autoradiography label in medical imaging, and in emerging self-powered lighting and betavoltaic battery applications. Applications in cost-effective removal of tritium from natural waters and from nuclear reactor process waters are also needed and could be enabled by this research.

We propose research on hydrogen isotope separation using graphene in the Membrane Electrode Assemblies (MEAs) of Proton Exchange Membrane (PEM) electrochemical hydrogen pump cells to address technical challenges leading to practical implementation of this process. The study will investigate quantum understanding of H/D/T selectivity, characterize the large-area graphene membranes and solve isotope transport issues that can enable scale-up of separation processes.

In a recent study, the Clemson/SRNL team surpassed prior results at 14:1 H/D selectivity, and also demonstrated a 5000X increased proton flux using an improved cell design. The H/T selectivity was predicted to be higher at 59:1 but needs to be experimentally verified. An elegant method to scale-up the water isotope separation process has been proposed using PEM hydrogen pumping through a 2-D membrane in a counter-current flow in a circulation loop. Studies on H/D/T selectivity help to understand the isotope sieving mechanism in which a quantum tunneling hypothesis explains well that the isotope selectivity is independent of the type of membrane (e.g., graphene vs hBN). This proposal focuses on developing fundamental insights that would eventually lead to scale-up and allow efficient staged membrane separations.

The project is a collaboration among Savannah River National Lab, Clemson University and Vanderbilt University. Studies on tritium will be pursued at SRNL using graphene-containing electrochemical cells from Clemson with graphene from Vanderbilt University. SRNL will also develop a quantum tunneling mechanism on the isotopic sieving and start investigation to identify key technical needs for process scale up. Development of PEM-style electrochemical hydrogen pump cells with graphene included in the MEA will be pursued at Clemson. Clemson will also investigate mass transport in MEA cells that would eventually enable process scale-up with the circulation loop concept. Vanderbilt will develop and fabricate monolayer graphene and graphene/polycarbonate assembly to characterize the graphene lattice over centimeter-scale and probe the influence of diffusive transport on H/D selectivity in liquid state.

The principal project objective will be to test the following hypothesis: “Hydrogen isotope selectivity increased by graphene in a proton-exchange membrane (PEM) electrolysis cell is the result of quantum tunneling due to mass differences of H/D/T and how this selectivity can be maintained during scale-up.”