Degradation of octylbenzene sulfonate photoinduced by iron(III) aquacomplexes: Evidence for the fragmentation of the alkyl chain

Abstract

The degradation of octylbenzene sulfonate (OBS) photoinduced by iron(III) aquacomplexes was investigated upon irradiation at 365 nm and by solar light. The photochemical degradation appears to be due to HO• radicals arising from the electron transfer in Fe(OH)2+. If oxygen does not affect the initial quantum yield of OBS degradation, it is necessary to pursue the reaction up to, first the complete disappearance of OBS and secondly OBS mineralization. The nature of the major photoproducts gives evidence for a competitive attack of HO• radicals on the alkyl chain resulting in a shortening of the chain. Among the possible sites on the chain, hydrogen on the carbon in α position with respect to the aromatic ring was the main point of attack with the formation of 4-acetylbenzene sulfonate and 4-carboxylicbenzene sulfonate.