Cobalt ion species in water as an active homogeneous catalyst for oxidative decomposition of ammonium ion with ozone

粟飯原 はるか; 渡部 創; 柴田 淳広; 神谷 裕一*

no journal, , 

Treatment of accumulated radioactive liquid waste in laboratories is urgent task not only for effective utilization of the research fields but also for safety management of the facilities. Since the liquid waste has to be treated inside shielded devices such as concrete cell or grove box due to its radioactivity, easy operations for the treatment are preferred to prevent any unexpected accidents during the treatment. Decomposition of ammonium ion under mild reaction conditions has been successfully achieved in the presence of CoO4, which acts as a heterogeneous catalyst. We have demonstrated that cobalt(II) nitrate acted as a homogeneous catalyst for the reaction and chloride ion in water was indispensable for the catalyst to effective promote the reaction. In-situ XAFS were measured during blowing ozone. Conversion ratio of ammonium ion was significantly increased when both cobalt and chloride ions existed. Cobalt ion was keeping divalent, these ion assumed to produce OH radical to decompose ammonium ion.