Degradation of RDX by various advanced oxidation processes: II. Organic by-products

This study resulted in the detection and identification of several organic by-products that were formed upon photolysis or oxidation of RDX by various advanced oxidation processes (AOPs). Photolysis of RDX by UV showed evidence of formation of two by-products, probably by the successive elimination of two equivalents of nitrous acid. These were tentatively identified as I, S-dinitro-l, 3, 5-triazacyclohex-5-ene and I-nitro-l, 3, 5-triazacyclohex-3, 5,-ene. Both of these compounds were present as intermediates and disappeared upon further photolysis. Three other by-products were also detected which persisted for the entire duration of the photolysis process. These were identified by derivatization with O-pentafluorobenzylhydroxylamine (PFBHA) and subsequent extraction and GC/MS. Two of these were positively identified as PFBHA derivatives of formamide and urea. Oxidation of RDX by processes involving ozone also led to the detection of formamide and urea (as PFBHA derivatives) early in the oxidation process. However, these compounds disappeared with the progress of the oxidation process. Four other by-products which were detected only during degradation of RDX by oxidation processes involving ozone. Two were tentatively identified as N-hydroxy formamide and nitro formaldehyde, and the apparent molecular weights of the others were 88 and 102. (C) 1998 Elsevier Science Ltd. All rights reserved.