Oxidative decomposition of ammonium ion with ozone in the presence of cobalt and chloride ions for the treatment of radioactive liquid waste

粟飯原 はるか; 渡部 創; 柴田 淳広; Mahardiani, L.*; 大友 亮一*; 神谷 裕一*

Progress in Nuclear Energy, 139, p.103872_1 - 103872_9, 2021/09

AA2020-0412.pdf:1.22MB

https://doi.org/10.1016/j.pnucene.2021.103872

To prevent unexpected accidents at nuclear facilities caused by accumulated ammonium nitrate in an aqueous liquid waste containing ammonium salts and nitric acid, NH in the liquid waste must be decomposed under mild reaction conditions. In this study, we investigated the oxidative decomposition of NH with O at 333 K in the presence of a homogeneous Co catalyst and Cl in the wide pH range of the test solution. The reaction behavior was greatly affected by pH of the test solution. In a basic solution at pH 12, high conversion of NH was obtained even in the absence of Co and Cl and the main product was NO . However, Co and Cl in the solution greatly enhanced the decomposition rate of NH in acidic to mild basic solutions (pH 1-8), while only low conversion of NH was observed unless both Co and Cl were present. For the reaction with Co and Cl in the solutions, NH was transformed mainly into chloramines (NH Cl , x = 1-3) by the reaction with HClO, which was formed by the reaction of Cl with O catalyzed by the homogeneous Co catalyst, and led to the high decomposition rate of NH . Cl suppressed the formation of the precipitate CoO(OH) during the reaction and consequently the Co catalyst stably existed in the reaction solution, which was another reason for the high decomposition rate of NH in the presence of Cl. Owing to the swift decomposition of NH under mild reaction conditions and small formation of secondary waste, the oxidative decomposition of NH in the presence of the homogeneous Co catalyst and Cl is suitable and applicable for the treatment of the aqueous liquid waste containing ammonium salts and nitric acid.

Initial oxidation of Si(001) induced by translational kinetic energy of O supersonic molecular beams

吉越 章隆; 佐野 睦; 寺岡 有殿

Japanese Journal of Applied Physics, Part 1, 39(12B), p.7026 - 7030, 2000/12

https://doi.org/10.1143/JJAP.39.7026

超音速O分子線を用いて、O分子の並進運動エネルギーを変化させ、それによって誘起されるSi(001)表面酸化過程をXPS及び散乱分子線測定により明らかにしたので発表する。SiOの脱離を伴う酸化(Active oxidation)では、O分子の運動エネルギーが、3.0eV及び2.0eVの場合、基板温度700において、SiOの脱離及びO分子の散乱割合に大きな変化が見られた。しかし、並進運動エネルギーが、0.5及び1.0eVではこれらの現象がみられないことから、O分子の並進運動エネルギーがActive oxidationを増強する効果があることを見いだした。SiOの脱離を伴わない酸化(Passive oxidation)においても並進運動エネルギーの効果が見いだされた。酸化が、1.0eV及び2.6eVの並進運動エネルギーで増加した。これらは、Si表面の第1層のback bond及び第2-第3層間の酸化に対応することが、理論計算のこれまでの報告との比較よりわかった。