Mediated electrochemical oxidation process: Electro-oxidation of cerium(III) to cerium(IV) in nitric acid medium and a study on phenol degradation by cerium(IV) oxidant

Cerium(III) in nitric acid medium was oxidized electrochemically using a flow type electrochemical cell fabricated in our laboratory. The variation of applied cell current, temperature and the concentration of the electrolyte were studied to determine the oxidation efficiency of Ce(III) in the electrochemical cell. The conversion yield of cerium(IV) in nitric acid was 97% in a short duration of 90 min. A bench scale degradation of phenol has been carried out by mediated electrochemical oxidation process using this oxidised Ce(IV) species. The influence of the concentration of phenol, temperature, amount of cerium, and the concentration of the electrolyte were studied on phenol destruction in a batch type reactor. It was found that nearly 70% of phenol was found to be destructed within 10 min. A good degradation yield was obtained above 70 ◦C. The effects of concentrations of cerium and nitric acid on phenol degradation were found to be moderate within the range investigated. The course of the reaction was followed by TOC analysis, estimating the CO2 evolved, and also measuring the potential of the Ce(IV)/Ce(III) redox couple.