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The preparation of anodic TiO2 nanotube layers has been performed using electrochemical anodization of Ti foil for 4 h at different voltages (from 0 V to 80 V). In addition, a TiO2 thin layer has been also prepared using the sol–gel method. All the photocatalysts have been characterized by XRD, SEM, and DRS to investigate the crystalline phase composition, the surface morphology, and the optical properties, respectively. The performance of the photocatalyst has been assessed in versatile photocatalytic reactions including the reduction of N2O gas and the oxidation of aqueous sulfamethoxazole. Due to their high specific surface area and excellent charge carriers transport, anodic TiO2 nanotube layers have exhibited the highest N2O conversion rate (up to 10% after 22 h) and the highest degradation extent of sulfamethoxazole (about 65% after 4 h) under UVA light. The degradation mechanism of sulfamethoxazole has been investigated by analyzing its transformation products by LC-MS and the predominant role of hydroxyl radicals has been confirmed. Finally, the efficiency of the anodic TiO2 nanotube layer has been tested in real wastewater reaching up to 45% of sulfamethoxazole degradation after 4 h. [ABSTRACT FROM AUTHOR]

The key role of trivalent manganese (Mn(III)) species in promoting sulfate radical-based advanced oxidation processes (SR-AOPs) has recently attracted increasing attention. This review provides a comprehensive summary of Mn(III) (oxyhydr)oxide-based catalysts used to activate peroxymonosulfate (PMS) and peroxydisulfate (PDS) in water. The crystal structures of different Mn(III) (oxyhydr)oxides (such as α-Mn2O3, γ-MnOOH, and Mn3O4) are first introduced. Then the impact of the catalyst structure and composition on the activation mechanisms are discussed, as well as the effects of solution pH and inorganic ions. In the Mn(III) (oxyhydr)oxide activated SR-AOPs systems, the activation mechanisms of PMS and PDS are different. For example, both radical (such as sulfate and hydroxyl radical) and non-radical (singlet oxygen) were generated by Mn(III) (oxyhydr)oxide activated PMS. In comparison, the activation of PDS by α-Mn2O3 and γ-MnOOH preferred to form the singlet oxygen and catalyst surface activated complex to remove the organic pollutants. Finally, research gaps are discussed to suggest future directions in context of applying radical-based advanced oxidation in wastewater treatment processes. [ABSTRACT FROM AUTHOR]

In this study, we employed nano zero-valent iron catalysts supported on graphitized carbon (GC-nZVI) catalyst to efficiently degrade BPA under circumneutral pH conditions in both dark and UVA radiation. The GC-nZVI catalyst was characterized using specific techniques (XPS, FTIR, BET, etc.), and was used to activate both PS and PMS in solution. Although no significant BPA degradation constant (k BPA) was determined using PS/PMS or GC-nZVI alone, a significant synergistic effect was observed in the system. Under dark conditions, k BPA increased from 0.01 min−1 to 0.17 when PS was used, both in the dark and under UVA. Notably, when PMS was present in the system, the improvement was even higher with k BPA reaching 0.18 and 0.26 min−1 under dark and UVA conditions, respectively. To further support the synergistic effect, it was found that 80% of mineralization was achieved within 2 h of UVA exposure. Chemical quenching experiments were conducted using selective probes and kinetic modelling showed that the activation of PS/PMS produced sulfate radicals (SO 4 •−), hydroxyl radicals (•OH) and ferryl ions (FeIVO2+) in both systems. Additionally, GC-nZVI/PMS system demonstrated good stability in recycling experiments, with up to 70% of BPA still being degraded after 3 cycled in 1 h under UVA. In conclusion, the degradation efficiencies of GC-nZVI/PMS and GC-nZVI/PS systems under dark and UVA radiation were assessed for three different EDCs (BPA, E2, and EE2) in both tap and sewage treatment plant waters. This study has demonstrated that the highly efficient GC-nZVI/PS/UVA or GC-nZVI/PMS/UVA system has significant potential for application in different water matrix, and our findings provide insights into the design of heterogeneous Fenton-like and photo-Fenton-like catalysts. [Display omitted] • GC-nZVI with PS and PMS systems is able to degrade and mineralize BPA in water. • The steady-state concentration of reactive species such as HO.•, SO 4 •- and FeVIO2+ is determined • The main degradation products of BPA are characterized. • Efficient BPA, E2 and EE2 degradation was obtained using GC-nZVI + PMS under UVA. • 60% of EDCs degradation in Tap and STP waters was reached after 90 min. [ABSTRACT FROM AUTHOR]

TiO 2 nanotube (TNT) layers are prepared via electrochemical anodization of Ti foil in ethylene glycol-based electrolyte containing fluoride ions. Using spin-coating of Fe(III) precursor solutions of different concentrations (10 µM to 10 mM), iron surface-modified TNT (Fe-TNT) layers are formed after annealing at 450 °C for 2 h in air. The Fe-TNT layers are comprehensively characterized by XRD, SEM, DRS and XPS. To identify and assess the contribution of photocatalysis and Fenton-based processes that are simultaneously triggered by Fe-TNT layers, degradation of caffeine is investigated in the dark and under UVA with and without the presence of 500 µM H 2 O 2. It has been found that in the presence of H 2 O 2 under UVA, 100 µM Fe-TNT can degrade 67 % of caffeine after 3 h, of which 4 % is from photolysis, 23.5 % from photocatalysis and 39.5 % from Fenton-based processes. It is important to note that Fenton-based reactions are due to the iron leaching, while the main reactive oxygen species are identified as hydroxyl radicals. In addition, the main degradation by-products are identified by LC-MS and IC-MS techniques, thus leading to the proposal of different degradation pathways of caffeine. To sum up, the research's findings provide novel insights into the concept of photochemical versatility, which is only obliquely explored in the corpus of previous research. [Display omitted] • Fe modified TiO 2 nanotube layers trigger simultaneous processes. • Contribution of photocatalysis, Fenton and photolysis is assessed for the first time. • Fenton process is dependent to iron leaching from Fe-TiO 2. • Efficient degradation of caffeine under UVA in the presence of H 2 O 2. • Degradation pathway of caffeine is proposed using LC-MS and IC-MS data. [ABSTRACT FROM AUTHOR]