Investigation on TiO2-coated optical fibers for gas-phase photocatalytic oxidation of acetone

A preliminary optical fiber reactor (OFR) that employs bare quartz fibers a s a light-transmitting support of TiO2 was tested for gas treatment by inve stigating photocatalytic oxidation of acetone in air (50-750 ppmv). Using o ne or four TiO2-coated fibers in a continuous flow photoreactor, a steady-s tate conversion up to 80% was achieved at ambient temperature and pressure. The kinetic behavior of the acetone conversion in this study could be desc ribed by zero-order kinetics. The characteristics of coated-optical fibers were quantitatively analyzed and their use in photocatalytic gas treatment was discussed in detail. All the acetone molecules degraded was quantitativ ely converted to CO2 with no intermediates detected. No noticeable deactiva tion was observed within a few hours' operation under the present experimen tal conditions. The conversion of acetone linearly increased with the incid ent light intensity without showing any sign of saturation. The transmitted light intensity through a TiO2-coated optical fiber exponentially decrease d along the fiber, showing 90% extinction within 30 cm. The photocatalytic conversion measured as a function of the coated-fiber length showed a simil ar trend. An optimal coating thickness was found at around 1.5 mum above wh ich the photocatalytic efficiency was reduced. The presence of water vapor reduced the reactivity due to the competitive adsorption on active surface site with acetone. While a measurable conversion of acetone was observed in the absence of O-2, increasing O-2 concentration up to 15% effectively enh anced the conversion. (C) 2001 Elsevier Science B.V. All rights reserved.