Degradation of tributyltin chloride in water photoinduced by iron(III)

The degradation of tributyltin chloride (TBT) photoinduced by iron(III) was investigated. Upon irradiation at λexcitation >300 nm a photoredox process was observed, yielding iron(II) and ·2OH radicals. The disappearance of TBT was proved to involve only an attack by ·2OH radicals: the quantum yield of TBT disappearance was determined. A wavelength effect was observed; the shorter the excitation wavelength, the higher the rate of TBT disappearance. Most of the photoproducts were identified and the mechanism of degradation was elucidated. The main route to degradation is a stepwise debutylation of TBT to di- and mono-butyltin with final formation of inorganic tin. The complete mineralization of TBT was achieved with long irradiation times, leading to innocuous inorganic tin.