Acid-regulated electron flux in recycled ZVMg for nitroglycerin reduction: Mechanistic elucidation and kinetic modeling

Energetic materials (EMs) bound to propellant residues pose potential environmental and public health risks without effective treatment. Considering the proven efficacy of zero-valent magnesium (ZVMg) in EM reduction and the increasing emphasis on recycling manufacturing waste from granular magnesium processing lines, in this study, wasted ZVMg activated by acetic acid was used for the reductive degradation of nitroglycerin (NG). Batch NG reductive degradation experiments were carried out for a range of ZVMg solid to liquid ratio (S/L) ratios (between 0.5% and 10%) and initial acetic acid concentrations (between 0.1% and 3%). NG removal ranged between 11% and 100% within 20 min across all experiments, and Mg^{2 +} analysis suggested that the reductive degradation of NG was controlled by the electron flux originating from the reaction between ZVMg and acetic acid. A comprehensive kinetic model was developed and globally fitted to experimental observations of NG and Mg²⁺ by solving a system of ordinary differential equations (ODEs). The developed model was capable of capturing the trends of measured NG and Mg²⁺ concentrations with a coefficient of determination (R²) exceeding 98%. The developed kinetic model offers a practical approach to describing and predicting NG removal under varying conditions in a ZVMg-catalyzed acetic acid system.