Exploring Disposal Efficiency of COD, NH₃-N, and Turbidity in Diluted Real Leachate Using Ti/PdO-CoO Electrodes in an Electrooxidation Cell: An Investigation into Oxidation Mechanism and Reaction Kinetics Studies

In this study, Pd and Co metal oxides, electrochemically deposited on a titanium (Ti) substrate, were utilized to remove chemical oxygen demand (COD), NH 3 -N, and turbidity from diluted Bingöl leachate. The plating bath was prepared with 7 mM palladium chloride (PdCl 2 ) and 1 mM cobalt chloride (CoCl 2 ), along with 1.68 M NH4Cl, and 0.16 M H 3 BO 3 . In the electrooxidation (EO) cell, the anode consisted of a Ti/PdO-CoO electrode, while the cathode was a stainless-steel electrode. The Ti/PdO-CoO electrode demonstrated an actual functional life of 96 h, as determined through accelerated life testing. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy examinations revealed that the surface of the Ti substrate was coated with PdO and CoO. Turbidity, NH 3 -N, and COD were electrooxidized indirectly due to the high chloride content (718 mg l −1 ). In the presence of 10 mM NaCl, the highest removal efficiency for NH 3 -N, COD, and turbidity was 60.5%, 64.9%, and 96.5%, respectively. The removal of COD, NH 3 -N, and turbidity fit pseudo-second-order (PFO) kinetics (R 2 0.97–0.99). For a COD efficiency of 60.5% at 25 mA cm −2 , the corresponding energy consumption, unit energy consumption, and electrode cost were 56.25 kWh m −3 , 200.89 kWh/kg-COD, and 2.37 ($/kg-COD), respectively.