Performance optimization and mechanism of HMX degradation by Fenton oxidation method

Abstract

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) has been widely used in rocket propulsion, military, artillery manufacturing, and mining industries. However, HMX exhibits high toxicity and is difficult to biodegrade, which may cause serious environmental pollution. In this study, Fenton oxidation was employed to treat HMX wastewater, and the degradation performance under different conditions, as well as the degradation mechanism and toxicity changes, were investigated. The results showed that the degradation performance reached its optimum under reaction conditions of pH = 3.0, H₂O₂ concentration of 30.0 mmol/L, and Fe²⁺ concentration of 0.7 mmol/L, with a removal rate of up to 90.8%. The degradation followed pseudo-first-order kinetics. The degradation intermediates of HMX in the Fenton oxidation system were analyzed by tandem mass spectrometry (MS/MS), and possible pathways for the Fenton oxidation degradation of HMX were proposed. The molecular toxicity level of HMX wastewater, represented as the transcriptional effect level index, increased to 1.69 in the early stage of degradation and gradually decreased to 1.46 (non-toxic) during the degradation process. Molecular-level toxicity analysis revealed significant dysregulation of functional genes related to oxidative stress, possibly caused by H₂O₂ present in the Fenton process and the generated highly oxidative ·OH. This study provides new insights into the Fenton degradation mechanism and molecular-level toxicity evolution during HMX degradation, and offers scientific basis for the health risk assessment and control measures of energetic material wastewater.