Comparison between O-3/VUV, O-3/H2O2, VUV and O-3 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/H2O2 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/H2O2 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/H2O2 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/H2O2 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. Copyright (C) 1996 IAWQ. Published by Elsevier Science Ltd.