The Influence of Light Irradiation on the Photocatalytic Degradation of Organic Pollutants

Abstract

The design of a photocatalytic process must consider intrinsic and extrinsic parameters affecting its overall efficiency. This study aims to outline the importance of balancing several factors, such as radiation source, total irradiance, photon flux, catalyst substrate, and pollutant type in order to optimize the photocatalytic efficiency. Titanium oxide was deposed by the doctor blade technique on three substrates (microscopic glass (G), flour-doped tin oxide (FTO), and aluminum (Al)), and the photocatalytic properties of the samples were tested on two pollutants (tartrazine (Tr) and acetamiprid (Apd)). Seven irradiation scenarios were tested using different ratios of UV-A, UV-B + C, and Vis radiations. The results indicated that the presence of a conductive substrate and a suitable ratio of UV-A and Vis radiations could increase the photocatalytic efficiency of the samples. Higher efficiencies were obtained for the sample Ti_FTO (58.3% for Tr and 70.8% for Apd) and the sample Ti_Al (63.8% for Tr and 82.3% for Apd) using a mixture of three UV-A and one Vis sources (13.5 W/m2 and 41.85 μmol/(m2·s)). A kinetic evaluation revealed two different mechanisms of reaction: (a) a one-interval mechanism related to Apd removal by Ti_FTO, Ti_Al (scenarios 1, 4, 5, and 7), and Ti_G samples (scenario 7) and (b) a two-interval mechanism in all other cases.

Development of Photocatalytic 3D-Printed Cementitious Mortars: Influence of the Curing, Spraying Time Gaps and TiO2 Coating Rates

“…The similar photocatalytic efficiency for all the series up to 4 h of light irradiation may be ascribed to the accumulation of adsorbed pollutants and the produced dye decomposition products onto the specimens' surface, which could partially inactivate the reaction sites [44]. Nonetheless, by increasing the light exposure period up to 8 h, the The similarity of the results reveals that the difference in coating time does not extensively influence the photocatalytic efficiency.…”

“…The similar photocatalytic efficiency for all the series up to 4 h of light irradiation may be ascribed to the accumulation of adsorbed pollutants and the produced dye decomposition products onto the specimens' surface, which could partially inactivate the reaction sites [44]. Nonetheless, by increasing the light exposure period up to 8 h, the reaction products generated by the degradation mechanism had enough time to be removed from the surface of the specimen, and the TiO 2 nanoparticles could be reactivated in order to degrade a higher quantity of pollutants.…”

Heterogeneous Photocatalysis of Metronidazole in Aquatic Samples

“…From the data presented, it can be observed that the time required to remove MET from solution decreases with increasing irradiance. The increase in MET photodegradation efficiency can be explained by the conversion of total irradiance to photon flux, which was involved in the photocatalytic radical generation processes OH • and O •− 2 [65]. The application of irradiance of 250 W m −2 , corresponding to the daily GHI for Poland, does not allow the complete removal of MET from the solution within 60 min.…”

Special Issue: Photocatalytic Materials for Environment Treatment and Energy Production

“…Three of the total eight articles [ 1 , 2 , 3 ] are focused on TiO 2 -based photocatalysts, as TiO 2 has been extensively studied as a low-cost and environmentally friendly material with relatively high photocatalytic activity and excellent chemical stability.…”

“…In Reference [ 1 ], TiO 2 (Degussa P25) films were deposited using the doctor blade technique on three different substrates: microscopic glass (G), flour-doped tin oxide (FTO) and aluminum (Al). The photocatalytic properties of the samples were tested on two pollutants, tartrazine (Tr) dye and acetamiprid (Apd) insecticide, under UV-A, UV-B + C and VIS irradiations (seven scenarios) for 8 h. In order to optimize the photocatalysis efficiency, the influence of several parameters (irradiation source, total irradiance value, photon flux, catalyst substrate and pollutant type) were studied.…”