Degradation of sodium 4-dodecylbenzenesulphonate photoinduced by Fe(III) in aqueous solution

The Fe(III)-photoinduced degradation of 4-dodecylbenzenesulphonate (DBS) in aqueous solution was investigated. The mixing of DBS (1 mm) and Fe(III) (1 mm) solutions immediately led to the formation of a precipitate that conta ined DBS and monomeric Fe(OH)(2+), the predominant Fe(III) species. Both sp ecies were also present in the supernatant. Irradiation of the supernatant solution resulted in a photoredox process that yielded Fe(II) and . OH radi cals. The disappearance of DBS was shown to involve only attack by . OH rad icals; the quantum yield of DBS disappearance is similar to the quantum yie ld of . OH radical formation. A wavelength effect was also observed; the ra te of DBS disappearance was higher for shorter wavelength irradiation. Five photoproducts, all containing the benzene sulphonate group, were identifie d. . OH radicals preferentially abstract hydrogen from the carbon in the al pha position of the aromatic ring. The results show that the Fe(III)-photoi nduced degradation of DBS could be used as an alternative method for pollut ed water treatment. (C) 2000 Elsevier Science Ltd. All rights reserved.