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Ag(II)‑mediated electrochemical oxidation technique for organic radioactive waste treatment and analytical applications Gitika Saheb Singh1 · D Banerjee2 · C Srinivas1  Received: 8 July 2020 / Accepted: 23 November 2020 © Springer Nature Switzerland AG 2020

Abstract Present paper reports development of Ag(II)-mediated electrochemical oxidation technique for the management of radioactive organic wastes namely cation, anion & mixed ion exchange resins, tributyl phosphate in n-dodecane and its vacuum distillation residue, generated in nuclear facilities. Best conditions are found out for highly efficient mineralization of these wastes at normal temperatures using this technique. Additionally, the non-selective oxidizing power of Ag(II) is utilized to develop analytical methods for environmentally important parameters, viz., total organic carbon, chemical oxygen demand in waters, sulfur content of products like paper. These results are also presented. Keywords  Mediated electrochemical oxidation · Organic radioactive waste · Purex solvent · Total organic carbon and Chemical oxygen demand

1 Introduction Oxygen is a non-selective oxidant at high temperatures (800–1000 °C) and this property is used in incineration process to manage different organic solid and liquid wastes with high volume reduction. However, incineration is losing its importance rapidly, in the recent decades, because of the emission of toxic furan, dioxin and other air pollutants in improperly controlled incineration process. Presence of radioactive materials and corrosive gases such as S­ O2, ­NOx, ­P2O5 in the off gas makes the incineration process more complex for the management of organic radioactive wastes such as ion exchange resins and tributyl phosphate solvent [1]. Eco-friendly alternative options to incineration are in various stages of development. Metal ion mediated electrochemical oxidation (MEO) is one such promising benign option, especially for treatment of organic radioactive wastes. MEO is a lowtemperature mineralization reaction in aqueous medium at atmospheric pressure. Ag(II),Co(III) and Ce(IV)-mediated

MEO methods have been studied for mineralization of different organic wastes arising from nuclear and defense facilities [2–7]. In the present study, MEO of cation, anion, mixed ion exchange resins, 30% TBP in n-dodecane solvent (hereinafter, TBP solvent) and its vacuum distillation residue (hereinafter, pot residue) using Ag(II) as mediator catalyst was carried out to arrive at the best conditions. Literature information, to the best of authors’ knowledge, is not available for the listed organic materials in detail. Our MEO studies led to development of novel analytical methods for environmentally important parameters. These results are also presented.

2 Theory Electrolytic and chemical reactions in the MEO with Ag(II) as mediator catalyst are described below: All the standard electrode potentials shown in this paper are with respect to standard hydrogen electrode.

*  C Srinivas, [email protected] | 1SIES Indian Institute