Applied Catalysis B: Environmental 33 (2001) 239–248 Degradation of dibutyl phthalate by homogeneous photocatalysis with Fe(III) in aqueous solution Oliver Bajt a , Gilles Mailhot b , Michèle Bolte b,∗ a Marine Biological Station, Fornace 41, 6330 Piran, Slovenia b Laboratoire de Photochimie Moléculaire et Macromoléculaire, UMR CNRS-Université Blaise Pascal No. 6505, 63177 Aubière Cedex, France Received 25 November 2000; received in revised form 11 March 2001; accepted 31 March 2001 Abstract The degradation of dibutyl phthalate (DBP) photoinduced by Fe(III) in aqueous solution has been investigated under monochromatic irradiation and sunlight. Hydroxyl radicals • OH, responsible of the degradation, are formed via an intra- molecular photoredox process in excited Fe(III) aquacomplexes. The concentration in Fe(OH) 2+ in the starting Fe(III) solution appears to be a controlling parameter of the degradation rate, as already stated in our previous works. The first step of the decomposition of DBP involves the hydrogen abstraction on the butyl chain mainly on the carbon in -position to aromatic ring. The major primary photoproducts are hydroxy, dihydroxy and carboxylic derivatives. For prolonged irradiations, DBP and its photoproducts are completely mineralized due to the regeneration of the absorbing species and the continuous formation of • OH radicals that confers a catalytic aspect to the process. Consequently, the degradation photoinduced by Fe(III) could be an efficient method of DBP removal from water. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Dibutyl phthalate (DBP); Fe(III); Hydroxyl radicals; • OH; Photodegradation 1. Introduction Dialkyl phthalates are widely used as plasticizers in different resins, especially PVC resins [1], in addi- tion, dibutyl phthalate (DBP) is an important additive in special paints and adhesives. As a consequence, di- alkyl phthalates are released into the natural environ- ment during manufacture, use, disposal and leaching from plastic materials. This is the case of the Slovenian coastal area where wastewaters from the local chem- ical industry producing plasticizers, are introduced into river Rizana and subsequently into the Bay of Koper (gulf of Trieste, northern Adriatic). The dialkyl ∗ Corresponding author. Tel.: +33-4-73-40-71-71. E-mail address: michele.bolte@univ-bpclermont.fr (M. Bolte). phthalate concentrations measured in wastewaters of this chemical industry were around 100 mg l -1 . Dialkyl phthalates have been detected in natural waters, marine sediments and biota [2–4] where they appear as toxic compounds [5,6]. Moreover, DBP has been considered as teratogenic compound to aquatic organisms [7]. The toxic properties of DBP are even more important considering its high bioaccumulation rate (range from 100 to 3000) in different organisms [8]. Dibutyl phthalate is a rather stable compound in the natural environment. The hydrolysis half-life was estimated to be about 20 years [8]. Studies of its bio- degradation in fresh waters, marine waters, sediments, wastewaters and sludge revealed rather low degrada- tion rate in the range of several days up to a few months 0926-3373/01/$ – see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0926-3373(01)00179-5