Degradation reaction of monoethanolamine using TS-1 zeolite as a photocatalyst

Abstract

Photocatalytic properties of TS-1 zeolite were examined via a degradation reaction of monoethanolamine (MEA). When TS-1 was mixed with MEA aqueous solution, the MEA molecules were bonded to the Ti atoms in TS-1 since the latter were coordinatively unsaturated. In fact, the Ti atoms in TS-1 were isolated and coordinated by four oxygen atoms. The change in the coordinative situation around the Ti atom shifted the absorption of ultraviolet (UV) light from about 220 nm, which is intrinsic absorption of TS-1, to a longer wavelength, i.e. around 300 nm. When the suspension mixture of TS-1 and MEA aqueous solution was irradiated by UV light with a wavelength of around 300 nm, photo-excitation of the MEA-adsorbed Ti species took place leading to a degradation of MEA molecules. Although a photocatalytic activity per weight of a specimen was lower for TS-1 than for TiO₂, the activity per Ti atom in TS-1 was higher than that in TiO₂. The strong adsorption of MEA to TS-1 and its microporous structure are attributed to the high activity of the photocatalytic reaction. The use of either TS-1 or TiO₂ as a photocatalyst had no effect on the kind of products and the product ratios.