DEGRADATION OF DIMETHYL METHYLPHOSPHONATE IN AQUEOUS SOLUTION BY OZONE

Dimethyl methylphosphonate (DMMP), which acted as a simulant of nerve warfare agent, was degraded by ozone in this study. Several operation parameters such as initial pH value, ozone flow, ozone concentration, temperature and initial concentration of DMMP were investigated. Experimental results showed that DMMP could be degraded rapidly by ozone. In the optimum working conditions, 99% 50 mg/L DMMP were degraded in 16 min, and 44% total organic carbon of the solution were reduced. Moreover, the free radical accelerant, Fe2+, and inhibitors, 2-propanol and tert-butanol significantly influenced the degradation efficiency of DMMP. Free radicals were the most important oxidants for the DMMP degradation reaction in this system. The following instrumental quality analyses, such as gas chromatogrphy-mass-spectrometry (GC-MS), ion chromatography (IC) and infrared spectroscopy (IR) indicated that methyl methylphosphonate, methyl phosphoric acid, formic acid, phosphate anion and carbon dioxide, etc. were formed after the treatment. Ozone could be decomposed to form hydroxyl radical, which could attack DMMP to start the degradation reaction. Furthermore, DMMP would probably be mineralized. Fi-nally, three reaction pathways were predicted for the DMMP degradation by ozone.