Electrochemical oxidation of humic acid and sanitary landfill leachate: Influence of anode material, chloride concentration and current density

The influence of applied current density and chloride ion concentration on the ability of Ti/Pt/PbO2 and Ti/Pt/SnO2–Sb2O4 anodes for the electrochemical oxidation of humic acid and sanitary landfill leachate samples was assessed and compared with that of BDD anode. For the experimental conditions used, results show that both organic load and nitrogen removal rates increase with the applied current density and chloride ion concentration, although there is an optimum COD/[Cl−]0 ratio below which there is no further increase in COD removal. Metal oxide anodes present a similar performance to that of BDD, being the results obtained for Ti/Pt/PbO2 slightly better than for Ti/Pt/SnO2–Sb2O4. Contrary to BDD, Ti/Pt/PbO2 promotes lower nitrate formation and is the most suitable material for total nitrogen elimination. The importance of the optimum ratio of Cl−/COD/NH4+ initial concentrations is discussed. [Display omitted] •Ti/Pt/PbO2 and Ti/Pt/SnO2–Sb2O4 anodes have similar performance to that of BDD.•Ti/Pt/PbO2 presents better performance than Ti/Pt/SnO2–Sb2O4 for pollutants removal.•Ti/Pt/PbO2 promotes the lowest nitrate formation and the highest TN elimination rate.•Optimum COD/[Cl−] for maximum chloride indirect oxidation performance•COD and TN removals increase with current density and in the presence of Cl−.