Efficiency Factors in Photocatalytic Reactors: Quantum Yield and Photochemical Thermodynamic Efficiency Factor

Abstract

Photocatalytic efficiency is evaluated using quantum yields (QYs) and the photochemical thermodynamic efficiency factor (PTEF). The PTEF allows establishing reactor efficiency as the ratio of utilized enthalpy for the formation of consumed OH . free radicals over the absorbed photon energy. A key consideration for the evaluation of efficiency factors is the establishment of macroscopic energy balances together with an accurate assessment of evolved and absorbed photons. Of considerable help are the experimental devices developed at the Chemical Reactor Engineering Centre (CREC)/University of Western Ontario (UWO) laboratories. Photoconversion kinetics is required for calculation of the OH . consumption rates and establishment of the related kinetic parameters. PTEFs and QYs have been applied by CREC-UWO researchers for efficiency calculations in photocatalytic reactors for the decontamination of air, water, and hydrogen production.

Photoreduction of a Pd-Doped Mesoporous TiO2 Photocatalyst for Hydrogen Production under Visible Light

“…The QY is defined as the formed H• molar rate over the absorbed photons molar rate. Thus, it describes the extent of the photochemical utilization for hydrogen production of absorbed photons [34]. The QY is calculated according to the following equation: dt is the rate of moles of hydrogen radicals formed at any time during the photocatalyst irradiation.…”

“…It is shown, that the near-UV light photoreduced mesoporous Pd-TiO 2 displays a 2.51 eV energy band gap. The near-UV light photoreduced Pd-TiO 2 photocatalyst is evaluated in a Photo-CREC Water-II Reactor (PCW-II Reactor) under visible light [34]. Ethanol is employed as an organic scavenger to help with electron-hole separation [33].…”

Degradation of Atenolol in a Rectangular Staircase Photocatalytic Reactor with Immobilized ZnO

“…A GMBE represents the kinetics of ATL degradation as a function of the contact time and of the initial concentration, as proposed after the substitution of Eqs. (14) and (15)…”

“…Many studies are available on the development of various types of solar photocatalytic reactors, where the semiconductor catalyst is generally in the form of powder suspended in a liquid medium [12][13][14][15][16]. The inconvenience of this as a large-scale approach is the catalyst recovery step from the solution at the end of operation.…”

Light Sources for Photochemical Processes – Estimation of Technological Potentials

“…The radiation is emitted in every direction along the arc. To ensure that a maximum of emitted photons is absorbed, the lamps are often submerged within the reaction mixture . Because light sources produce heat, a cooling finger is necessary to prevent the lamps and the reaction from overheating.…”