Comparison of silver(II), cobalt(III), and cerium(IV) as electron transfer mediators in the MEO mixed waste treatment process
Mediated electrochemical oxidation (MEO) has been developed as a method to treat mixed hazardous waste. The technology has for the most part been targeted toward wastes generated by the nuclear industry, consisting of a hazardous or non-hazardous organic material contaminated by a radioactive substance. The MEO process consists of the electrochemical generation of a powerful oxidizing agent, which serves as an electron transfer mediator to bring about the oxidation of the organic component. Numerous studies on a variety of organic substrates have demonstrated complete oxidation to carbon dioxide can be realized under the proper reaction conditions, with water serving as the source of oxygen. The radioactive component, usually an actinide element or heavy metal isotope, can then be recovered from the resulting organic free aqueous solution by standard methods such as ion exchange or solvent extraction. In addition to the variety of organic compounds tested, investigators have also looked at a number of process parameters including choice of mediator, temperature, concentration of mediator, current density, anode material, acid concentration, and cell separator material. From these studies it would appear that for a given organic substrate, the two most important process parameters are choice of mediator and temperature. The purpose of this work is to evaluate these two parameters for a given organic material, holding all other parameters constant. The organic material chosen for this study is the industry standard sulfonated styrene-divinyl benzene based cation exchange resin. This material is ubiquitous throughout the nuclear complex as a process residue, and is very resistant to chemical attack making it an ideal substrate to evaluate MEO capability. A high acid concentration is necessary to solubilize the mediator in its higher oxidation state, 6 M nitric acid was chosen since it is compatible with existing subsequent actinide element recovery processes.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 548643
- Report Number(s):
- LA-UR-97-2810; CONF-9709118-; ON: DE98000805; TRN: 99:002040
- Resource Relation:
- Conference: I&EC symposium, Pittsburgh, PA (United States), 15-17 Sep 1997; Other Information: PBD: [1997]
- Country of Publication:
- United States
- Language:
- English
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