Towards green magnesium preparation using a recyclable argon plasma anode for continuous electrolysis in molten chlorides

During the magnesium electrolysis process, graphite anodes are prone to consumption and fragmentation, disrupting normal operations and releasing greenhouse gases. In this study, we introduce a continuous, carbon-free approach to magnesium electrolysis using a stable argon plasma as the anode. The argon plasma anode operates via two distinct electrochemical stages: argon ionization at an average potential of 347.3 ± 95.3 V and chlorine evolution at 124.5 ± 9.0 V. A protective boron nitride (BN) coating on the tungsten collector filament significantly reduces corrosion. Atomic emission spectroscopy confirms the presence of Ar⁺ ions, whose concentration increases with current. Thermodynamic calculations and reaction analysis demonstrate that Ar⁺ facilitates chloride oxidation via the reaction: 2Ar⁺ + 2Cl^- → 2Ar + Cl₂. This research demonstrates the feasibility of argon plasma as an inert anode for chloride-based molten salt electrolysis, offering a sustainable alternative for magnesium production and potential applications in other high-temperature corrosive environments.