The effect of photon source on heterogeneous photocatalytic oxidation of ethanol by a silica–titania composite

Abstract

Abstract:The objective of this study was to distinguish the effect of photon flux (i.e., photons per unit time reaching a surface) from that of photon energy (i.e., wavelength) of a photon source on the silica-titania composite (STC)-catalyzed degradation of ethanol in the gas phase.Experiments were conducted in a bench-scale annular reactor packed with STC pellets and irradiated with either a UV-A fluorescent black light blue lamp (Amax=365 nm) at its maximum light intensity or a UV-C germicidal lamp (Amax=254 nm) at three levels of light intensity. The STC-catalyzed oxidation of ethanol was found to follow zero-order kinetics with respect to CO 2 production, regardless of the photon source. Increased photon flux led to increased EtOH removal, mineralization, and oxidation rate accompanied by lower intermediate concentration in the effluent. The oxidation rate was higher in the reactor irradiated by UV-C than by UV-A (38.4 vs. 31.9 nM S-I) at the same photon flux, with similar trends for mineralization (53.9 vs.43.4%) and reaction quantum efficiency (i.e., photonic efficiency, 63.3 vs. 50.1 nmol CO 2 ~mol photons-I). UV-C irradiation also led to decreased intermediate concentration in the effluent . compared to UV -A irradiation. These results demonstrated that STC-catalyzed oxidation is enhanced by both increased photon flux and photon energy.

Photocatalytic degradation of saccharin under UV‐LED and blacklight irradiation

“…41 That means that increase in light intensity enhances to a lesser extent the process efficiency, thus lowering the photonic efficiency. This tendency has been also reported by Chen et al and Coutts et al 40,42 and highlights the need for the right balance between removal efficiency and energy consumption when it comes to the determination of light intensity.…”

“…This tendency has been also reported by Chen et al . and Coutts et al . and highlights the need for the right balance between removal efficiency and energy consumption when it comes to the determination of light intensity.…”

Photocatalytic performance of highly amorphous titania–silica aerogels with mesopores: The adverse effect of the in situ adsorption of some organic substrates during photodegradation

“…[14]The photocatalytic activity of mesoporous titania and titania-silica composites synthesized by the sol-gel method is recently a hot topic of materials research. [15,16,17,18,19,20,21,22]Pure titania aerogels were shown to be more efficient photocatalysts than titania-silica aerogels.However, it should be emphasized, thatcomposite aerogels usually lack the structural homogeneity of TiO 2 and SiO 2 phases on the atomic scale. [23,24] In other words, some micro-or nanocrystalline TiO 2 , usually in the form of anatase, is always present dispersed in the structure, and this crystalline phase is responsible for the photocatalytic effect.In this work we present a family of titaniasilica aerogels in which no crystalline TiO 2 can be detected by X-ray diffraction methods.…”

Photocatalytic Selectivities of Ethane, Methane and Dimethylether Controlled by Reaction Conditions and TiO2 Structure in the Degradation of Acetic Acid

“…However, with the variation of residence time, pollutant types and their concentrations, the amount of products as well as intermediates could be decreased, or increased with light intensity . In accordance with this, for example, Vincent et al .…”