Molten salt oxidation process of strontium hazardous waste in Li2CO3-Na2CO3-K2CO3 melt

To address the disposal challenge of radioactive cellulose-based protective equipment (e.g., gloves) from nuclear power plants, this study evaluated the oxidation behavior of Sr-doped gloves via Molten Salt Oxidation (MSO) technology, comparing three molten salt systems (chloride, carbonate, nitrate). Key analysis focused on oxidation efficiency, residue characteristics, and Sr immobilization mechanisms. Experimental results identified the ternary eutectic carbonate system (Li₂CO₃-Na₂CO₃-K₂CO₃) as the optimal, featuring a low eutectic temperature (393 °C), high Destruction Removal Efficiency (DRE), high Capacity Reduction Efficiency (CRE), good thermal stability, and non-corrosiveness. Resource conservation and oxidation efficiency were balanced at a salt-to-waste mass ratio of 1:2. Sr showed two temperature-dependent effects: it accelerated cellulose degradation and decreased activation energy (from 98.194 kJ·mol −1 to 94.942 kJ·mol −1 ) at >450 °C, but it hindered oxidation at <400 °C (molten salt not totally molten). In order to achieve atomic-level immobilization, Sr first produced SrO at 400–450 °C. At ≥500 °C, a spontaneous reaction (Gibbs free energy <0) converted Sr into thermally stable SrCO₃ (decomposition Gibbs free energy >0), at 800 °C, the Sr interception rate reached 95.1%. This study confirmed MSO with the ternary carbonate system (1,2 ratio) achieves deep mineralization of organic matter in radioactive gloves while efficiently immobilizing Sr. It overcomes defects of traditional methods (incineration causing nuclide volatilization, vitrification consuming high energy, cement solidification having a high leaching rate), providing a safe, efficient, and eco-friendly solution for radioactive personal protective equipment disposal in nuclear power plants.