Platinum-modified titanium anodes for the electrolytic destruction of nitric acid

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• 作者：C. Mallika ; B. Keerthika ; U. Kamachi Mudali
• 关键词：Pt plated Ti anode ; Oxide coated Ti anode ; Surface characterization ; Electrolysis ; Nitric acid destruction
• 刊名：Electrochimica Acta
• 出版年：2007
• 出版时间：1 August 2007
• 年：2007
• 卷：52
• 期：24
• 页码：6656-6664
• 全文大小：843 K

文摘

Three sets of electrodes, namely Pt electroplated Ti (PET) and diffusion annealed PET (DAPET) of plating thickness 3, 5, 7 and 10 μm and thermochemically glazed mixed oxide coated titanium anode (MOCTA-G) were evaluated for their performance, with a view to optimizing the current density conditions for maximum efficiency during the electrolytic destruction of nitric acid. In the acid killing by electro-reduction process, concentration of nitric acid in the high level waste (HLW) from the spent nuclear fuel reprocessing plant was brought down from about 4 to 0.5 M in order to reduce the amount of HLW by subsequent evaporation and to minimise the corrosion in waste tanks during storage of the concentrated waste solution. The electrochemical reduction of 4 and 8 M nitric acid to near neutral conditions was carried out with the above-said anodes and Ti cathode at various cathodic current densities ranging from 10 to 80 mA cm⁻². At current densities below 15 mA cm⁻² MOCTA-G electrode worked satisfactorily, whereas PET and DAPET electrodes could withstand and function well at much higher cathodic current densities (up to 80 mA cm⁻²). The life assessment of a 3 μm thick PET electrode at a cathodic current density of 60 mA cm⁻² in 8 M HNO₃ for a period of 110 h showed no failure. Phase identification of the plated electrodes was done by XRD measurements and their surface morphology was investigated by SEM.