Reaction Rate Study of the Photocatalytic Degradation of Dichloroacetic Acid in a Black Body Reactor

Abstract

The light-induced degradation of dichloroacetic acid in aqueous suspensions containing the TiO2 photocatalyst Hombikat UV 100 was investigated. The reactions were performed in a black body reactor in which the rate of conversion, defined as the time derivative of the extent of conversion, is not affected by the light scattering properties of the photocatalysts. At sufficiently high concentrations of both the probe compound and the photocatalyst the rate of conversion was found to be unswayed by the initial concentration of the probe compound, the mass concentration of the photocatalyst, and the suspension volume. Thus, the chosen experimental conditions enable the determination of the rate of conversion and the quantum yield of the light induced degradation of dichloroacetic acid in aqueous photocatalyst suspension with sufficiently good reproducibility. The experimental procedure employed here seems to be generally applicable to determine rates of conversion and quantum yields that possibly allow a comparison of the activities of photocatalysts in aqueous suspensions.

Role of Hydrogen-Related Defects in Photocatalytic Activity of ZnO Films Grown by Atomic Layer Deposition

“…At such saturation coverage, any change in the concentration does not influence the photocatalytic kinetics . While the most photocatalytic data on ZnO in literature were analyzed using the first order kinetics, , there are several reports on the zero order reactions for different photocatalytic materials, including TiO 2 , SrTiO 3 , or Fe 3 O 4 …”

TiO2 Photocatalysis for the Transformation of Aromatic Water Pollutants into Fuels

“…The photocatalytic oxidation of organic pollutants proceeds either by the direct attack of the photogenerated holes or via the attack of the highly reactive hydroxyl radicals generated at the surface of the photocatalyst [110]. The photocatalytically generated OH • radicals can abstract hydrogen atoms from the organic molecules, causing a chain of reactions toward lower molecular in- By far, heterogeneous photocatalysis has gained the most attention as one of the most realistic and viable solutions due to its ability to clean-up a wide range of environmental pollutants besides the use of low-cost and chemical stable photocatalysts [101][102][103][104][105][106][107][108]. This promising approach relies on the excitation of a semiconductor with suitable light, e.g., the sunlight, to drive different redox reactions.…”

Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark

“…13,15,20,23 Alternatively, other novel hardware-based approaches can be also found in the literature to screen F directly, such as the integrating sphere embedded reactor 17,23 and the black-body reactor. 22,24,25 When compared with the optimal photonic efficiency approach, hardware-based approaches are useful and even more powerful complementary techniques to quantify F functions directly if the locally absorbed photon flux profile along the photoreactor cell is accessible. Nevertheless, typical applications of the black-body reactor design suffer from unaccountable light distributions, 24,25 which is key to reporting a meaningful F function, 21,25,26 whereas the integrating sphere design restrictions in terms of photoreactor design make it less amenable to the comprehensive standardization of photocatalytic rates.…”

“… 22 , 24 , 25 When compared with the optimal photonic efficiency approach, hardware-based approaches are useful and even more powerful complementary techniques to quantify Φ functions directly if the locally absorbed photon flux profile along the photoreactor cell is accessible. Nevertheless, typical applications of the black-body reactor design suffer from unaccountable light distributions, 24 , 25 which is key to reporting a meaningful Φ function, 21 , 25 , 26 whereas the integrating sphere design restrictions in terms of photoreactor design make it less amenable to the comprehensive standardization of photocatalytic rates. 17 , 23 In this context, if Φ (or IQE) quantification is technically not possible, a possible methodology to reflect experimental discrepancies in different groups without imposing a particular photoreactor design is to include an internal standard material in the optimal photonic efficiency approach, assuming that its intrinsic Φ is measurable and universally consistent.…”