Hydrogen Isotope Separation from Aqueous Streams using Zeolite Membranes
- Georgia Institute of Technology, Atlanta, GA, 30332-0100 (United States)
- Materials Science and Technology Division, Oak Ridge National Laboratory: Oak Ridge, TN, 37831 (United States)
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States)
- Nuclear Security and Isotope Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States)
Efficient separation of heavy hydrogen isotopes {sup 3}H (or T, tritium) and {sup 2}H (or D, deuterium) from {sup 1}H has been a long-standing endeavor in nuclear fuel cycle research and development. For example, tritium (half-life 12.3 years) is a fission product from nuclear plants and is found as tritiated water (HTO) in effluent streams from nuclear installations. Tritium must be concentrated and removed from such aqueous streams for waste storage. The separation of deuterium from deuterated water (HDO) has applications in heavy water production, and can also be used as a nonradioactive simulant in HTO separation research. Several methods have been explored such as ion exchange/adsorption and membrane permeation. Adsorption by molecular sieving materials such as zeolites can separate tritiated water from water with moderate selectivity (HTO/H{sub 2}O separation factor∼1.2-1.4) due to a subtle difference in adsorption characteristics between the two species. However, there remains a requirement for high-selectivity continuous separation of heavy hydrogen isotopes from water. Here we demonstrate new results on the use of zeolite membranes as a potential high-performance, low-cost, radiation-stable candidate for such separations. In zeolite membranes, separation of HTO (or HDO) from water would take place by a combination of adsorption and diffusion characteristics. Here we describe the hydrogen isotope separation properties of silicoaluminophosphate (SAPO-34) membranes synthesized on porous α-alumina supports. D{sub 2}O/H{sub 2}O feed mixtures of realistic compositions are used as a non-radioactive simulant for tritiated water feeds. Our results show promising applications of zeolite membranes for hydrogen isotope separation and recovery. In summary, SAPO-34 membranes were fabricated and investigated to demonstrate their pervaporative separation properties for D{sub 2}O-H{sub 2}O binary systems. These membrane exhibit high selectivity (up to ∼19) for D{sub 2}O and good permeance (> 600 GPU) even at low concentrations of D{sub 2}O in the feed, making them highly interesting candidates for capture of heavy hydrogen isotopes (D and T) from aqueous streams encountered in the nuclear fuel cycle. The mechanism of separation appears to involve both diffusivity and adsorption differences as expected in nanoporous materials, even though detailed identification of their respective contributions is a subject of future work. We also hypothesize that tritiated (T{sub 2}O/H{sub 2}O) mixtures will also show similar performance in relation to the present deuterated mixtures. This is planned to be further investigated through pervaporation measurements. (authors)
- OSTI ID:
- 22991828
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 114, Issue 1; Conference: Annual Meeting of the American Nuclear Society, New Orleans, LA (United States), 12-16 Jun 2016; Other Information: Country of input: France; 10 refs.; Available from American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 United States; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tritium Separation from High Volume Dilute Aqueous Streams- Milestone Report for M3FT-15OR0302092
Investigation of Sorption and Diffusion Mechanisms, and Preliminary Economic Analysis