Destruction of organic pollutants by cerium(IV) MEO process: A study on the influence of process conditions for EDTA mineralization

The mediated electrochemical oxidation (MEO) process with cerium(IV) and nitric acid as the oxidizing medium was employed for the destruction of various model organic pollutants in continuous organic feeding mode. A near complete destruction was observed for all the organics studied. The effects of various experimental conditions were evaluated with respect to EDTA mineralization. The key parameters varied in the process were concentration of EDTA (67-268 mM), temperature (70, 80 and 95 °C), concentrations of Ce(IV) (0.7, 0.8 and 0.95 M), nitric acid (2, 3 and 4 M) and duration of organic addition (30 and 120 min). Under the experimental conditions of 80 °C and 0.95 M Ce(IV) in 3 M nitric acid, nearly 90% destruction was achieved based on CO2 production and 95% based on TOC analyses for all the organic compounds studied. The in situ regeneration of mediator ion by the electrochemical cell was found to be good during the organic destruction within the range of experimental conditions studied. In the case of long term organic feeding (120 min) the destruction was calculated after the CO2 evolution attained the steady state and under this condition the destruction efficiency was found to be 85% based on CO2 evolution.