Photoassisted Degradation of n-Butyltin Chlorides in Air-Equilibrated Aqueous TiO₂ Suspension

Abstract

The photoassisted degradation of n-butyltin chlorides in air-equilibrated aqueous TiO2 suspension has been studied. Several factors affecting the degradation rate, such as the extent of adsorption on the surface of catalyst particles and the effect of pH values, were examined. Particular interest is focused on the TiO2-assisted photodegradation of n-butyltin species. The simultaneous photodeposition of tin oxides/metallic tin on the TiO2 surfaces is also addressed as a route to form surface-complexed semiconductors. A mechanism consisting of interfacial trapping of a photogenerated electron−hole pair can explain the observed photoassisted degradation of n-butyltin species and the simultaneous photodeposition of tin onto the TiO2 surface. The results are compared with those, previously reported, on the photolytic degradation of these species in water.

Ultraviolet degradation of methyltins: Elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

“…They proved that the degradation of TBT is due to the attack of OH radicals, and the main route to degradation is a stepwise debutylation of TBT to di-and mono-butyltin with final formation of inorganic tin. In order to accelerate the degradation rate in aqueous solution, TiO 2 was used for photocatalytic degradation of butyltin compounds under UV illumination (Navio et al, 1996). The photodegradation of triphenyltin in water was also studied Crosby, 1978, 1980).…”

The effect of acetic acid on the photocatalytic degradation of catechol and resorcinol

“…Diminishing hole-electron recombination rate favours hydroxyl groups and oxygen molecule reaction on the semiconductor surface and the production of oxidizing radicals, such as OH and O 2 À [12][13][14][15].…”

Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

“…Accordingly, many researchers have focused on the impacts of TBT on living organisms, and also on effective options for TBT degradation. Photo-degradation is one of the techniques of interest for removing TBT from surface water and sediment utilising, UV and solar light radiation [8][9][10][11]. Previous work indicates that neither volatilization nor degradation of TBT species dissolved in water occurs over a period of 2 months in the dark at room temperature [8].…”

“…However, these is only one reported attempt at the photo-assisted degradation of butyltin in aqueous TiO 2 suspension (Degussa P25, 1-5 m) calcined at 500 • C in an UV reactor. This achieved a 30% reduction in TBT concentration within 30 h [10,15]. The lower percentage degradation without catalyst might be due to the specific energy of the UV used in the reactor not being sufficient to generate electron-hole pairs from the catalyst, and the slightly large particle size of catalyst used.…”

“…The band gap energy of TiO 2 corresponds to the wavelength of UV light <400 nm [10,16]. Since sunlight consists mainly of visible wavelengths, these do not fit with TiO 2 band gap.…”