Comparison between o/vuv, o/ho, vuv and o processes for the decomposition of organophosphoric acid triesters

O 3 /vacuum ultraviolet (VUV, ultraviolet radiation by a low pressure mercury lamp at 185 and 254 nm), O 3 /H 2 O 2 and VUV processes rapidly decomposed organophosphoric acid triesters (OPEs) dissolved in distilled water as compared to simple ozonation. The O 3 /VUV process was the fastest of the three advanced oxidation processes (AOPs) for the decomposition of 1 mg/l of OPEs in pH 7.5 phosphate buffer solution (0.5 mM). However the difference between the pseudo-first-order rate constants of the O 3 /VUV and O 3 /H 2 O 2 processes decreased in the condition of increasing OPEsw concentration, and the efficiencies of the two processes were almost the same at an initial concentration of 20 mg/l. Contrary to results in distilled water, in an effluent from a solid waste landfill site, the O 3 /H 2 O 2 process was the fastest. This is manily due to the absorption of VUV radiation by nitrate ion. WE confirmed that nitrate ion of more than a few mg/l strongly interfered with the generation of hydroxyl (OH) radicals from VUV radiation while the O 3 /H 2 O 2 process was not affected. The use of an ESR-spin trapping technique revealed that AOPs generated more OH radicals than ozonation alone, and the detection of hydrogen atom confirmed that VUV radiation directly generated OH radicals from water.