Conversion of aniline wastes to value-added products is always a promising method to treat aniline wastewater. In this study, a selective oxidation of aniline contaminants by Bi 2·15 WO 6 was carried out under visible light and alkaline conditions. Kinetic results show that the oxidation rates of aniline increase with increasing pH values under visible light. UV–vis absorption spectra and GC-MS analysis confirm that azobenzene is the primary oxidation product with aminophenol and N , N ′-diphenylhydrazine as the secondary products. The analyses from Mott-Schottky, electrochemical impedance spectroscopy (EIS), transient photocurrent and photoluminescence (PL) further indicate that OH − promotes the separation and transfer of photogenerated electron-hole pairs on the surface of Bi 2·15 WO 6 , thus facilitating oxidation of aniline. Quenching experiments and electron spin resonance (ESR) analysis confirm that h + is the predominant specie in the Bi 2·15 WO 6 system and aniline radical cation (PhNH 2 •+ ) is an important intermediate. The Hammett and ΔBDE N-H plots further reveal that e - abstraction from aniline with the formation of PhNH 2 •+ , followed by H + abstraction from PhNH 2 •+ with the formation of anilino radicals (PhNH • ), is the prerequisite for the formation of N , N ′-diphenylhydrazine, which is then oxidized to azobenzene via the hydrogen-abstraction pathway. This work provides a cost-effective method to selectively oxidize aniline to azobenzene.
BiOI/Bi 2 WO 6 /MXene composite was successfully synthesized via a solvothermal method, confirmed by XPS/XRD. • Optimal composite degraded 89.3% ranitidine and mineralized 56.0% in 2 h. • EPR analysis indicated that superoxide radicals (•O₂ − ) dominate the degradation process. Ranitidine, a widely used acid-suppressing drug, can undergo nitrosation in aquatic environments to generate N -nitrosodimethylamine (NDMA), a potent carcinogen that poses a serious threat to aquatic ecosystems. To address its persistence against natural degradation, a ternary BiOI/Bi₂WO₆/MXene composite was fabricated via a one-pot solvothermal synthesis. Heterojunction construction effectively broadened its visible-light harvesting capacity. Characterizations by SEM, TEM, XRD, and UV–Vis DRS confirmed the successful formation of the heterojunction with markedly enhanced visible-light absorption. Combined with band structure analysis and radical trapping experiments, a Z -scheme charge transfer mechanism was proposed. Visible-light photocatalytic tests showed that the optimal sample exhibits a high degradation efficiency of 89.3% for RAN, with a 47% relative enhancement compared with pristine BiOI. Radical identification revealed that superoxide radicals (·O₂ − ) were the dominant reactive species. The synergistic effect between the electron-conductive MXene and the interfacial heterojunction accelerated photogenerated carrier separation and ·O₂ − production. Moreover, the composite retained 72.35% of its degradation efficiency after three cycles, demonstrating good stability. This work provides a novel material design strategy for visible-light-driven ranitidine degradation and offers a theoretical basis for mitigating NDMA formation risks.
Fei Meng,Muhammad Haris Khan,Shafqat Ali,Zareen Zuhra,Dugang Chen,Zhaowei Zhang
The environmental persistence and potential toxicity of microplastics have raised serious concerns regarding their impacts on aquatic ecosystems and human health. Herein, a Z-scheme heterojunction photocatalyst, MIL-53-NH 2 (Fe)/Bi 2 WO 6 , was rationally constructed to promote directional charge separation and enhance redox reactivity under light irradiation. Interfacial coupling between MIL-53-NH 2 (Fe)/Bi 2 WO 6 facilitates an efficient Z-scheme charge-transfer pathway, preserving the strong oxidation ability of photogenerated holes on Bi 2 WO 6 and the high reduction potential of electrons on MIL-53-NH 2 (Fe). When coupled with peroxymonosulfate (PMS), the heterojunction effectively activates PMS via electron-mediated pathways, leading to the generation of reactive oxygen species (ROS), primarily sulphate radicals (SO 4 •⁻ ), accompanied by the generation of hydroxyl radicals ( • OH) and superoxide radicals( • O 2 ⁻ ). As a result, polystyrene (PS) microplastics undergo accelerated oxidative chain scission, surface oxidation, and mass loss, achieving a weight reduction of 45.36% in the presence of 5 mM PMS. Radical quenching experiments and electron paramagnetic resonance (EPR) spectroscopy collectively confirm the dominant role of PMS-derived ROS and validate the proposed Z-scheme-driven degradation mechanism. This study elucidates the synergistic interplay between heterojunction charge dynamics and PMS activation, offering mechanistic insights into the design of efficient photocatalytic systems for microplastic degradation in aquatic environments.
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