SALT SPLITTING USING CERAMIC MEMBRANES

Inorganic ceramic membranes for salt splitting of radioactively contam inated sodium salt solutions are being developed for treating U.S. Dep artment of Energy tank wastes. The process consists of electrochemical separation of sodium ions from the salt solution using sodium(Na) Sup er Ion Conductors (NaSICON) membranes. In contrast to conventional org anic-based bipolar or ion exchange membranes used in salt splitting, N aSICON membranes are resistant to gamma/beta radiation and are highly selective for sodium ions. Potential applications include 1) caustic r ecycle for sludge leaching, regeneration of ion exchange resins, inhib ition of corrosion in carbon steel tanks, or retrieval of tank wastes; 2) pH adjustment and reduction of competing cations to enhance cesium ion exchange processes; 3) sodium reduction in high-level waste sludg es; and 4) sodium removal from acidic wastes to facilitate calcining. Initial experiments with dysprosium-based NaSICON membranes have demon strated the feasibility of the process.