Highly selective separation of pertechnetate from waste water

This work addresses the challenging problem of separating pertechnetate (TcO₄ ⁻) ions from huge (˜10¹⁰ times) NO₃ ⁻ background, which is very important for nuclear waste water treatment. It describes the facilitated transport based selective removal of ^99mTcO₄ ⁻ from aqueous feed solutions through a Tetraphenylarsonium perchlorate loaded polypropylene based supported liquid membrane. Keeping in mind the possible aqueous waste compositions in the nuclear industry, the transport selectivity of ^99mTcO₄ ⁻ has been studied in the presence of varying concentrations of NO₃ ⁻, CO₃ ^2- and OH⁻ ions. As NO₃- is the major anion in aqueous nuclear waste solutions, major importance has been given to study the selectivity of ^99mTcO₄ ⁻ over NO₃ ⁻. The transport selectivity has been studied using radiotracer technique as well as ion chromatography technique. Results indicate that the membrane is highly selective towards ^99mTcO₄ ⁻ considering even high concentration of NO₃ ⁻ does not hinder its transport appreciably. High decontamination factor for ^99mTcO₄ ⁻ over NO₃- and other anions has been obtained in all the cases. The promising results show the possibility of using this membrane-based fast process for nuclear waste treatment.