Removal of HMX, RDX, and TNT in water treatment process using alkaline sonolysis

HMX, RDX, and TNT are representative materials widely used in the manufacture of explosives. These compounds are recalcitrant organic contaminants that can persist in aquatic environments and contaminate water systems, leading to potential ecotoxicological impacts and risks to human health. Sonochemical reactions offer an effective alternative for the decomposition of these refractory compounds compared to conventional physicochemical treatments; toxic byproducts were also less likely. This study investigated the removal of these compounds using ultrasound, optimized conditions (frequencies and pHs), and analyzed byproducts with LC-MS/MS. Collaboration with alum coagulation was also reviewed. Ultrasound, particularly high-frequency (580 kHz), effectively degraded the explosives HMX, RDX, and TNT, although only approximately 30 % of the compounds were removed under these conditions. A high pH (>12) significantly improved removal, exceeding 95 % with 5-20 mM of NaOH, achieving complete removal of RDX and TNT within 60 min and HMX within 150 min. LC-MS/MS analysis showed degradation via OH radical hydroxylation and nitro-group reduction. Combining alkaline sonolysis pretreatment with alum coagulation was proposed for improved water treatment.