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Visible-light-driven Photocatalytic Removal of PPCPs using Magnetically Separable Bismuth Oxybromo-iodide Solid Solutions: Mechanisms, Pathways, and Reusability in Real Sewage
摘要： In testing a series of bismuth oxybromo-iodide (BiOBrxI1-x; 0 ≤ x ≤ 1) solid solutions, BiOBr0.9I0.1, due to its superior charge-carriers separation, exhibited the best performance in the visible-light-driven photocatalytic degradation of pharmaceutical and personal care products (PPCPs). Subsequently, its superparamagnetic version, BiOBr0.9I0.1/Fe3O4@SiO2, possessing a mesoporous hierarchical morphology, was solvothermally developed, and completely degraded the two model PPCPs, ibuprofen and benzophenone-3, in 1 and 2 h, respectively. Scavenger studies revealed that the ibuprofen degradation was dominated by e–, ?O2–, and h+, while the benzophenone-3 degradation was dominated by e– and ?O2–. Hydroxylation, decarboxylation, and demethylation were found to be the major reactions involved in the degradation pathways. The aquatic toxicity of the intermediates ― estimated using the ECOSAR software ― was found to be lower than for the parent PPCP molecules, indicating a reduced environmental risk after photocatalytic degradation. The solution matrix study elaborated the varying extent of the interacting roles of the co-present anions, cations, and NOM. The reusability and stability of BiOBr0.9I0.1/Fe3O4@SiO2 was examined in real secondary treated sewage in a prototype photocatalytic reactor equipped with a magnetic separator. Due to the interferences and unwanted interactions caused by the co-present constituents in secondary treated sewage, a gradual loss in the photocatalytic performance of BiOBr0.9I0.1/Fe3O4@SiO2 was observed during consecutive rounds of recycling.
关键词： visible-light-driven photocatalysis,magnetic photocatalyst,Bismuth oxyhalide,pharmaceuticals and personal care products,solid solution
更新于2025-09-19 17:15:36
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Reusable magnetic Ag/Fe, N-TiO2/Fe3O4@SiO2 composite for simultaneous photocatalytic disinfection of E.?coli and degradation of bisphenol A in sewage under visible light
摘要： A visible-light-driven and magnetic photocatalyst Ag/Fe,N-TiO2/Fe3O4@SiO2 (AgFeNTFS) was synthesized through a multi-step method. AgFeNTFS was tested for the photocatalytic disinfection of Escherichia coli (E. coli) and degradation of bisphenol A (BPA) under visible light irradiation, separately and simultaneously. The results showed that a 6.3-log reduction in cell density of E. coli was achieved and BPA (2 mg/L) was completely removed by AgFeNTFS in the separated photocatalytic processes within 120 min. In the simultaneous process, the photocatalytic disinfection of E. coli was not influenced in the presence of BPA, but the efficiency of BPA degradation was dropped by 10%. This was likely due to the competition for the same dominant reactive species of ?O2? and H2O2 between E. coli and BPA in the simultaneous process, as evidenced by the scavenger study and the interactions between the pollutants and AgFeNTFS. Moreover, the simultaneous photocatalytic activity of E. coli disinfection and BPA degradation by AgFeNTFS was investigated in the sewage obtained from a local wastewater treatment plant. The photocatalysis treated sewage could meet with the local disinfection discharge standard with a 3-log reduction of E. coli after 90 min, and a complete removal of BPA was achieved simultaneously after 360 min. Moreover, AgFeNTFS showed high magnetic separation efficiency and had a good reusability over three cycles for the simultaneous photocatalytic disinfection and degradation of BPA in both synthetic water and sewage. This study provides insights on the application of a reusable magnetic photocatalyst for simultaneous disinfection and degradation of BPA in sewage.
关键词： Simultaneous process,Visible-light-driven photocatalyst,Magnetic photocatalyst,Bisphenol A,Disinfection
更新于2025-09-11 14:15:04
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Magnetically Separable BiOBr/Fe3O4@SiO2 for Visible-light-driven Photocatalytic Degradation of Ibuprofen: Mechanistic Investigation and Prototype Development
摘要： The increasingly ubiquitous release of emerging refractory pollutants into water is a serious concern due to associated risks. In this study, mesoporous hierarchical BiOBr/Fe3O4@SiO2 ― a solvothermally synthesized visible-light-driven magnetic photocatalyst ― not only exhibited fast kinetics (t1/2 = 8.7 min) in the photocatalytic degradation of ibuprofen in water but also achieved almost complete mineralization over a prolonged irradiation of 6 h. Various reactive species, including ?O2?, ?OH, and H2O2, were detected, while the scavenging experiments revealed that eCB?-mediated reactions and direct-hole oxidation are the major degradation routes. The magnetically recycled BiOBr/Fe3O4@SiO2 maintained ~80% of its initial photocatalytic activity even after five consecutive cycles. The typically co-present wastewater constituents, including NOM and anions, inhibited the photocatalytic performance to varying extents, and hence necessitated an increase in the photocatalyst dosage to achieve complete ibuprofen degradation in real sewage. Based on the findings of batch experiments, the process was scaled up by developing a 5 L prototype photocatalytic reactor integrated with an electromagnetic separation unit. The results of prototype photocatalytic experiments were comparable to those of batch experiments, and an electromagnetic separation efficiency of ~99% was achievable in 5 min.
关键词： Magnetic photocatalyst,Photocatalytic reactor,Bismuth oxyhalide,Hierarchical photocatalyst,Pharmaceuticals and personal care products
更新于2025-09-10 09:29:36
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Preyssler-based nanocomposite as a magnetic photocatalyst: synthesis, characterisation and its photocatalytic activity for decolourisation of rhodamine B
摘要： In this work, the authors prepared a novel magnetic photocatalyst by grafting of Preyssler-type polyoxometalate, H14 [NaP5 W30 O110] onto Fe3O4 nanoparticles via an internal layer of silver nanoparticles. The obtained nanocomposite has been characterised by electron dispersive X-ray, transmission electron microscopy and scanning electron microscopy. The activity of the synthesised nanomagnetic photocatalyst was tested by the photocatalytic decolourisation of rhodamine B under UV light irradiation in the study’s designed reactor. It was found that, compared to pure Preyssler, decolourisation of rhodamine B was occurred four times faster using the synthesised magnetic nanocomposite with easy separation. The magnetic nanocatalyst was separated after ending the reaction and recycled. It just showed 2–3% decrease in catalytic activity after four recycling.
关键词： Preyssler-type polyoxometalate,Fe3O4 nanoparticles,photocatalytic decolourisation,rhodamine B,magnetic photocatalyst,silver nanoparticles
更新于2025-09-09 09:28:46
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Synthesis and photocatalytic activity of composite magnetic photocatalyst Mn <sub/>x</sub> Zn <sub/>1-x</sub> Fe <sub/>2</sub> O <sub/>4</sub> /α-Bi <sub/>2</sub> O <sub/>3</sub>
摘要： In this paper, a new magnetic photocatalyst MnxZn1-xFe2O4/α-Bi2O3 is synthesized by the dip-calcination technology, using manganese zinc ferrite as a magnetic substrate. It is beneficial to separate the composite from liquid solution under an extra magnetic field. This heterojunction of composite MnxZn1-xFe2O4/α-Bi2O3 presents remarkable photocatalytic activity and prominent photocatalysis for degradation of Rhodamine B (RhB), far exceeding the pure α-Bi2O3. Especially, the introduction of MnxZn1-xFe2O4 not only reduces the bandgap of photocatalyst α-Bi2O3, but also improves its response in the visible region. Importantly, the magnetic photocatalyst is capable of being used repeatedly, and the photocatalytic activity would remain above 90% after 3 cycles. Such an outstanding stability and retrievability of composite are mainly ascribed to the soft-magnetic material MnxZn1-xFe2O4, enhancing separation of photoinduced electron hole pairs. This work will replace the traditional semiconductor photocatalyst for a convenient recycling and removal of contaminants from wastewater in the future.
关键词： MnxZn1-xFe2O4,α-Bi2O3,photocatalytic activity,magnetic photocatalyst
更新于2025-09-09 09:28:46