Accelerated lifetime of Ti/RuO2 electrodes in environments with high concentrations of ammonia, chloride and organic matter

Electrooxidation has proven to be an efficient technique for treating effluents containing ammoniacal nitrogen and organic matter. In the present study, electrooxidation trials were conducted with an ammoniacal effluent generated at a fertilizer depot, containing 0.24 mol L−1 of N-NH3 and 0.90 mol L−1 of Cl−. The Ti/RuO2 electrodes were used in a stirred batch electrochemical reactor. The results obtained, employing a current density of 60 mA cm−2, showed degradation rates of 99.9% for ammoniacal nitrogen and 75.6% for organic matter. Accelerated anode degradation tests with the same solution, maintaining a constant current density of 1,000 mA cm−2, indicated that after 300 h, a partial dissolution of the RuO2 coating was observed, along with the formation of a passive TiO2 film and an increase of approximately 24% of the initial anodic potential value. Considering a working current density of 60 mA cm−2, the estimated service life of the Ti/RuO2 anode is 6 years.