VOC photodegradation at the gas-solid interface of a TiO2 photocatalyst - Part I: 1-butanol and 1-butylamine

The gas-solid heterogeneous photocatalytic oxidation of 1-butanol and 1-but ylamine in air was investigated using supported TiO2 as a catalyst. The sup ported catalyst was prepared using a sol-gel method and irradiated employin g two different light sources, a medium pressure mercury lamp or a xenon-ch loride excimer lamp. The experimental set-up was especially designed for ge nerating a gas stream containing stable and defined concentrations of the m odel pollutants. The gas stream at the reactor exit was analyzed on line by gas chromatography and the structures of the intermediates were establishe d by gas chromatography coupled with mass spectrometry. Six major intermedi ates (butanal, butanoic acid, 1-propanol, propanal, ethanol and ethanal) we re identified in the case of the photocatalytic degradation of 1-butanol. 1 -Butylamine was less efficiently adsorbed on the catalyst and its degradati on was slower. Three intermediates could be identified in this case (N-buty lidene-1-butylamine, N-ethylidene-1-butylamine and N-butylformamide). Based on these results, a degradation mechanism is proposed for both compounds. Mineralization could be achieved under various conditions of concentrations and flow rates and was confirmed by infrared spectroscopy. (C) 2000 Elsevi er Science S.A. All rights reserved.