Nanostructured ceramic membranes for hydrogen isotope separation

A process for removal of a heavy hydrogen isotope from an aqueous stream, the process comprising:

• contacting a hydrated separation phase with a first aqueous stream comprising the heavy hydrogen isotope, wherein the first aqueous stream is at a temperature of about 100° C. or less, the hydrated separation phase comprising a proton-conducting ceramic having an average grain size of about 500 nm or less, wherein upon the contact, the heavy hydrogen isotope of the first aqueous stream is exchanged with a first lighter hydrogen isotope of the hydrated separation phase and adsorbed to the hydrated separation phase, thereby purifying the first aqueous stream;
• subsequently, contacting the hydrated separation phase comprising the adsorbed heavy hydrogen isotope with a second aqueous stream, wherein the second aqueous stream is at a temperature that is greater than that of the first aqueous stream, wherein upon the subsequent contact, the adsorbed heavy hydrogen isotope of the hydrated separation phase is exchanged with a second lighter hydrogen isotope of the second aqueous stream.