Characterization and Comparative Performance of TiO2 Photocatalysts on 6-Mercaptopurine Degradation by Solar Heterogeneous Photocatalysis

Abstract

The crystallographic properties of two titanium dioxide (TiO2) photocatalysts, P25, and commercial C1-TiO2 reactive grade, were analyzed by X-ray diffraction (XRD) and the band-gap was calculated with UV–Vis spectrometry with integration sphere. Then, their performance was tested in the degradation of 6-mercaptopurine (6-MP) by heterogeneous photocatalysis with solar radiation under different pH conditions and the addition of hydrogen peroxide (H2O2); the degradation efficiency was monitored by UV–Vis spectrophotometry. The XRD analysis showed that both photocatalysts studied have anatase phase, while only P25 contains rutile; the band gap values were lower, in both catalysts, than those reported for catalysts obtained by the sol-gel method. With both photocatalysts, degradation experiments showed efficiency greater than 98% in experiments in the presence of H2O2 regardless of pH. The properties of the photocatalysts, along with the data obtained from the experimentation, helped determine the best semiconductor for the degradation of 6-MP with these operating conditions in this work.

Methylthionine chloride degradation on pilot UV-C reactors: Kinetics of photolytic and heterogeneous photocatalytic reactions

“…One of these processes is heterogeneous photocatalysis, which mainly uses TiO 2 as a semiconductor and UV radiation as activation energy, achieving the degradation of recalcitrant substances when destroying their chemical bonds, by generating gaps in electron pairs as there is a reaction between the organic substances and water (López-Ojeda et al, 2011). In this way, the complete mineralization of these pollutants can be achieved thanks to their degradation in a fast and non-selective manner to non-toxic substances (Bokare and Choi, 2014;González-Burciaga et al, 2020). Reactions taking place on the photocatalyst surface are (Gottschalk et al, 2000;Wang and Xu, 2012):…”

“…Photocatalysis technique has been used for the degradation of different recalcitrant substances of this type present in water, obtaining positive results (Lachheb et al, 2002;Akpan and Hameed, 2009;Rauf and Ashraf, 2009;Rauf et al, 2010;Kaur and Singhal, 2014;Muhd et al, 2014). Photocatalytic waste water treatments use different reactors where the semiconductor is fixed in a specific place in the system where it receives the UV radiation, which can be artificial by means of a lamp or natural solar, necessary for the reaction to occur (Pantoja-Espinoza et al, 2015;Abreu-Zamora et al, 2016;Núñez-Núñez et al, 2018;Cruz, 2019;González-Burciaga et al, 2020). To monitor the degradation of the pollutant in aqueous solution, the most widely used reactors are those that have TiO 2 supported on an immobile material, as long as the photocatalyst is in a phase of aggregation different from that of the compound to be degraded (De Felipe, 2008;Amador-Hernández et al, 2011).…”

“…One of the reactors that has been best adapted to the needs of degrading organic matter present in wastewater is the Japanese patent UBE reactor, which uses a photocatalytic material (TiO 2 /SiO 2 ) in its structure and applies UV-C radiation (λ = 254 nm) by lamp, achieving positive results in short reaction times (Pantoja-Espinoza et al, 2015;Núñez-Núñez et al, 2018;Cruz, 2019;González-Burciaga et al, 2020).…”

The Influence of Photoactive Heterostructures on the Photocatalytic Removal of Dyes and Pharmaceutical Active Compounds: A Mini-Review

“…The photogenerated electrons from the second photocatalytic systems will migrate to the electron medium, in order to recombine with the photogenerated holes from the first photocatalytic system. In this way, the opposite electrons and holes are involved in the reduction and oxidation reactions, which assure a highly efficient charge separation [ 57 , 58 , 59 ].…”

Solar Heterogenous Photocatalytic Degradation of Methylthionine Chloride on a Flat Plate Reactor: Effect of pH and H2O2 Addition

“…− (1.59 eV), among many others [35]. The OH redox potential is greater even than that generated by the holes (h + ) produced in the photocatalyst band jump (2.53 eV) [36,37]. These reactive species can degrade pollutants in a fast and non-selective manner until mineralization to produce non-toxic substances [38].…”