Jiehong He,Lanfang Han,Weiwei Ma,Liying Chen,Chuanxin Ma,Chao Xu,Zhifeng Yang
Photocatalytic microplastics (MPs) conversion into valuable products is a promising approach to alleviate MPs pollution in aquatic environments. Herein, we developed an amorphous alloy/photocatalyst composite (FeB/TiO 2 ) that can successfully convert polystyrene (PS) MPs to clean H 2 fuel and valuable organic compounds (92.3% particle size reduction of PS-MPs and 103.5 μmol H 2 production in 12 h). FeB effectively enhanced the light-absorption and carrier separation of TiO 2 , thereby promoting more reactive oxygen species generation (especially ‧OH) and combination of photoelectrons with protons. The main products (e.g., benzaldehyde, benzoic acid, etc.) were identified. Additionally, the dominant PS-MPs photoconversion pathway was elucidated based on density functional theory calculations, by which the significant role of ‧OH was demonstrated in combination with radical quenching data. This study provides a prospective approach to mitigate MPs pollution in aquatic environments and reveals the synergistic mechanism governing the photocatalytic conversion of MPs and generation of H 2 fuel.
Xueyan Li,Lei Wang,Xin Zheng,Xiang Tu,Anhong Cai,Jing Deng
In this study, a UV-driven photocatalytic activation of peroxymonosulfate (PMS) system was constructed using bimetallic metal-organic frameworks to degrade pharmaceuticals and personal care products (PPCPs). Mn-MIL-53(Fe) was successfully synthesised by adjusting the doping ratio of Mn using solvothermal method. The removal of ibuprofen (IBP) by UV/Mn-MIL-53(Fe)/PMS process was as high as 79.7% in 30 min with a Mn doping ratio of 1.0 (molar ratio of Mn to Fe), and the reaction rate constant was 26.9% higher than undoped. Mn-MIL-53(Fe) had been systematically characterized in terms of its physical structure, microscopic morphology, surface functional groups and photoelectric properties. The mechanism investigation revealed that the cycling of Mn and Fe accelerated the rate of electron transfer in the system, which significantly increased the activation efficacy of PMS to generate more hydroxyl and sulfate radicals for IBP degradation. A total of 13 transformation products were detected during the degradation of IBP by the UV/Mn-MIL-53(Fe)/PMS process. Theoretical calculations were used to predict the sites on the IBP molecule that were vulnerable to attack, and four possible degradation pathways were deduced. The excellent stability and efficient catalytic properties of Mn-MIL-53(Fe) provided a promising solution to the problem of water treatment contaminated with PPCPs.
Exploring effective approach to promote more comprehensive charge transfer and efficient spatial charge separation is considered to be a prospective strategy to reinforce photocatalytic degradation activity. Herein, the oxygen vacancy modified Bi 2 WO 6 /NH 2 -MIL-68(In) Z-scheme heterojunction photocatalyst was successfully fabricated via a facile solvothermal method. The chemical structure, morphology, and optical properties of the photocatalyst were characterized in detail. The optimized Bi 2 WO 6 /NH 2 -MIL-68(In) Z-scheme heterojunction displayed the maximum photocatalytic efficiency (84.3 %) for the degradation of levofloxacin (LEV), which was significantly higher than that of pure Bi 2 WO 6 (45.1 %), oxygen vacancy modified Bi 2 WO 6 (69.4 %), and NH 2 -MIL-68(In) (49.3 %). Importantly, the high-resolution mass spectrometry (HRMS), three-dimensional excitation-emission matrix (3D EEMs) fluorescence spectra, the photo-electrochemical and photo-luminescence measurement, radical trapping test, and electron spin resonance (ESR) technique were carried out to illuminate the probable degradation pathway and mechanism of the LEV. The improved photocatalytic efficiency can be ascribed to the synergetic effect between oxygen vacancy and the Z-scheme heterojunction, which can serve as trapping centers to enhance the generation of photoexcited electrons and accelerate the charge transfer. Meanwhile, the effects of pH, photocatalyst dose, LEV concentration and different kinds of harmful organic pollutants were systematically explored from the practical application. This study offers a novel perspective for the integration of defect engineering and Z-scheme heterojunction in efficient organic pollutants degradation.
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