Abstract
The increasing discharge of cobalt ions into the environment, driven by industrial and urban development, poses significant ecological challenges. This study optimized a chemical-free dielectric barrier discharge (DBD) plasma process to remove cobalt from water. Key parameters, including plasma treatment time (5–30 min), applied power (30–50 W), and gas flow rate (1–2 L/min), were systematically investigated for their impact on cobalt removal efficiency. Optimal conditions such as 25 min treatment time, 50 W power, and a 1.5 L/min flow rate achieved a maximum cobalt removal efficiency of over 99%, with an energy efficiency (EE) of 190.1 mg/kWh. Characterization via UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) revealed the formation of cobalt oxide particles (Co 3 O 4 and CoO) with an average size of 2.5 µm, suitable for catalytic applications. The oxidation of cobalt (II) ions to cobalt oxides was primarily driven by reactive oxygen species, such as hydroxyl radicals, generated during nonthermal plasma discharge.