The release of tritiated water from Cobalt(II) exchanged 4A zeolite into surrounding water

Tritium Separation from High Volume Dilute Aqueous Streams- Milestone Report for M3FT-15OR0302092

“…The membrane could be fully saturated by placing in a desiccator with ammonium chloride solution containing tritium for 14 days at ambient temperature. 9 Another approach to increase the preferential diffusion of HTO is to vary the self-diffusion coefficient of water in zeolite pores by incorporating cations such as cobalt or cesium (Co 2+ , Cs + ). According to the literature, 9 diffusion coefficient of water can be tuned by several orders of magnitude when the zeolite structure was exchanged with other cations mentioned above.…”

“…9 Another approach to increase the preferential diffusion of HTO is to vary the self-diffusion coefficient of water in zeolite pores by incorporating cations such as cobalt or cesium (Co 2+ , Cs + ). According to the literature, 9 diffusion coefficient of water can be tuned by several orders of magnitude when the zeolite structure was exchanged with other cations mentioned above. This is based on the hypothesis that one should expect slower diffusion of water when monovalent cation such as Na + is replaced with smaller divalent cation such as Co 2+ .…”

“…Traditional tritium separation technologies include combined electrolysis and catalytic exchange (CECE), palladium membrane reactor, and the highly energy intensive cryogenic distillation. [4][5][6][7][8][9][10] An alternative technology utilizing zeolite molecular sieve membranes was evaluated, which may demonstrate significant, low energy improvement over the available technologies for tritium separation. It was recently shown that silico alumino phosphate (SAPO-34) layered on porous alumina supports can perform separations by taking advantage of the differences in the rates of adsorption, molecular weight, and kinetic diameter of the molecules being separated.…”

“…The self-diffusion of several isotopic species of water such as H 2 O, HDO/D 2 O (heavy water) and HTO/T 2 O (tritiated water) has been reported. 9,11 The self-diffusion coefficients of H 2 O and HTO in sorbents such as zeolite 4A can differ by several orders of magnitude depending on the type of cations (Co, Ni, Cs, etc.) that replace Na in the zeolite structure.…”

“…that replace Na in the zeolite structure. 9 The goal in this proof of concept study is to evaluate the feasibility of separating tritium by taking advantage of the differences in adsorption and diffusion rates through the zeolite molecular sieve membranes.…”