Photocatalytic decomposition of acetaldehyde in air over titanium dioxide

Abstract

The photocatalytic decomposition of acetaldehyde in air at initial concentrations ranging from 3 to 200 mg m À3 has been studied in a semitransparent closed box with an inlet volume of 0.056 m 3 . The photocatalytic reactors consisted of a glass tube, 250 mm long with inside diameters of 28, 35, or 45 mm, whose inner surface was coated with a thin ®lm of titanium dioxide, and a 6-W blacklight uorescent lamp located at the axis of the glass tube. The decomposition of acetaldehyde was almost complete within 1±3 h and its main product was carbon dioxide. A kinetic study showed that the photocatalytic reaction obeys a Langmuir adsorption isotherm. Although the light intensity was certainly decreased with the distance from the light source, the degree of this decrease was much smaller than the degree of the decrease in the kinetic constants, which suggests that the light intensity is not simply proportional to the degree of the photo-excitation of TiO 2 and the rate of the resulting photocatalytic decomposition of acetaldehyde. # 1999 Society of Chemical Industry Keywords: photocatalytic reaction; acetaldehyde; titanium dioxide; photocatalytic reactor; batch recirculation systemVolume of a box (m 3 ) INTRODUCTIONIn highly airtight houses that have little ventilation in order to save on the amount of energy required to maintain the room temperature almost constant throughout the year, various kinds of volatile organic compounds are released from the adhesives and preservatives used in house-building materials or from furniture. These compounds then accumulate in increasing amounts in the airtight room, which leads, in turn, to the discomfort of the inhabitant and to health-related complaints.

Adsorption and Photocatalytic Decomposition of Volatile Organic Compounds on Photocatalyst of TiO2—Silica Beads

“…However, kinetic studies on photocatalytic decomposition of VOCs were limited. The Langmuir-Hinshelwood kinetic model was often used to explain the photocatalytic decomposition rate of VOCs (Kim and Hong, 2002;Bouzaza and Laplanche, 2002;Obuchi et al, 1999;Jian-Hua et al,1999;Xu and Shiraishi, 1999;Sopyan et al, 1996;El-Maazawi et al, 2000;Sauer and Ollis, 1996). However, photocatalytic decomposition rate was influenced by many factors such as activity and surface area of photocatalyst, light intensity, adsorption and desorption of reactants/products, presence of oxygen, humidity, etc.…”

Decomposition of gaseous formaldehyde in a photocatalytic reactor with a parallel array of light sources

“…The photocatalytic treatment of environmental pollutants is mostly carried out in a batch-recirculation mode [6,7,[9][10][11]. However, it should be noted here that when the reactor volume is much smaller than the volume of the air to be treated and the conversion of HCHO per one pass of the air through the photocatalytic reactor is very small, the batch-recirculation mode can be approximated by a batch mode [11].…”

Fabrication of TiO2 Nanotube by Electrochemical Anodization: Toward Photocatalytic Application

“…Recently, owing to the diverse application of titanium dioxide TiO 2 , a thorough research and experiments have been devoted to the preparation of titanium dioxide TiO 2 and the considerable number of parameters determining its formation. There is a vast amount of literature on the titanium dioxide application such as photoelectrochemical water splitting [1], water [2,3] and air purification [4], solar energy conversion [5], medical applications [6], gas sensors [7], and supercapacitors [8]. These applications rely on the specific semiconductor nature of TiO 2 , in particular anatase, which is an n-type semiconductor with a large band gap of about 3.2 eV [9].…”