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Oxidation of off flavor compounds in recirculating aquaculture systems using UV-TiO2 photocatalysis
摘要： Geosmin (GSM) and 2-methylisoborneol (MIB) are secondary metabolites of cyanobacteria that are often present in recirculating aquaculture systems (RAS) and are problematic, even at low (ng L-1) concentrations, due to their taste and odor effects on water and accumulation in the lipid tissue of fish. Removal of these compounds is difficult due to their extremely low concentrations and advanced treatment technologies, such as advanced oxidation processes (AOPs) have to be employed. In this study, a novel AOP consisting of immobilized TiO2 in a UV reactor was tested at bench scale for removal of GSM and MIB in both batch and continuous flow modes. Batch reactor application at a full-scale RAS resulted in average GSM and MIB removal efficiencies of 61% and 72%, respectively, with a 6 hour treatment time. No significant removal of GSM and MIB was observed in continuous flow mode, most likely due to both lower residence time and low initial concentrations of both compounds. No negative effects were observed on downstream biological wastewater treatment processes, indicating that the proposed UV-TiO2 process can be safely integrated into RAS.
关键词： Titanium dioxide,Photocatalysis,Geosmin,Off-flavor compounds,Recirculating Aquaculture Systems,2-methylisoborneol
更新于2025-09-09 09:28:46
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Characterization of perovskite LaFeO3 synthesized by microwave plasma method for photocatalytic applications
摘要： Perovskite LaFeO3 nanoparticles were successfully synthesized by microwave plasma method combined with high temperature calcination at 700–1000 °C. The influences of calcination temperature on morphology, crystalline structure, purity and the atomic compositions of samples were studied. The photocatalytic performance of LaFeO3 was evaluated though the photodegradation of Rhodamine B (RhB) under visible light. In this research, the orthorhombic LaFeO3 nanoparticles showed band gaps in the range of 2.15–2.30 eV. The particle size increased with increasing in the calcination temperature, leading to the decreasing in the surface area. The LaFeO3 sample calcined at 900 °C showed the highest photodegradation of 77.8% and the apparent rate constant of 0.0077 min?1 within 180 min because of the narrower of band gap and the higher crystalline degree and oxygen adsorption.
关键词： Photocatalysis,LaFeO3,Microwave plasma
更新于2025-09-09 09:28:46
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One-step synthesis of hollow BaZrO3 nanocrystals with oxygen vacancies for photocatalytic hydrogen evolution from pure water
摘要： It is very challenging to synthesize perovskite oxides with controlled morphology and defect states at the same time. In this work, the BaZrO3 hollow nanostructures with oxygen vacancies were facilely synthesized through one-step solvothermal method using ethylenediamine (EDA) as solvent. The as-synthesized BaZrO3 could split pure water into H2 without addition of sacrificial agent under UV light irradiation. The photocatalytic H2 production rate is about 15 times than that of the commercial BaZrO3 (BZO-C). It is believed that the presence of oxygen vacancies and the hollow morphology made contribution to the improvement of photocatalytic performance. This work provides a reference for microstructure and defect modification of photocatalysts at the same time to enhance the photocatalytic performance.
关键词： BaZrO3,Photocatalysis,Oxygen vacancy,Pure water,Hollow structure
更新于2025-09-09 09:28:46
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Effect of thickness of Cr layer on Ag cocatalyst surface for highly selective photocatalytic conversion of CO <sub/>2</sub> by H <sub/>2</sub> O
摘要： In this study, we developed a Ag–Cr core–shell-structured (Ag@Cr) cocatalyst that modified the surface of the Ga2O3 photocatalyst. Compared to results provided by modifications with Ag cocatalysts and M–Cr dual cocatalysts (M = Au, Cu, Pd, and Pt), this change significantly improved the formation rate of CO and selectivity toward CO evolution in the photocatalytic conversion of CO2 by the electron donor H2O. As a result of this modification, the Cr(OH)3?xH2O shell changed to Cr(OH)x(CO3)y during the photocatalytic conversion. Furthermore, the thickness of the Cr(OH)3?xH2O shell was found to influence the photocatalytic performance. More specifically, Cr(OH)3?xH2O shells that were too thick or too thin were not beneficial to the CO evolution and suppression of H2 evolution. Notably, the highest photocatalytic activity (525.3 μmol h?1), selectivity toward CO evolution (85.2 %), and turnover number of CO to Ag (167) was achieved over 0.25 mol% (Ag@Cr)/Ga2O3. In addition to Ga2O3, the Ag@Cr cocatalyst modification strategy can also be applied to other photocatalyst materials such as NaTaO3, ZnGa2O4, and ZnGa2O4/Ga2O3 for the highly effective photocatalytic conversion of CO2 to CO when using H2O as an electron donor.
关键词： carbon dioxide,chromium hydroxide,Photocatalysis,core–shell structure,Ag cocatalyst
更新于2025-09-09 09:28:46
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C(sp <sup>3</sup> )-H Bond Activation by Perovskite Solar Photocatalyst Cell
摘要： Inspired by the efficient perovskite solar cells, we developed a three-component hybrid perovskite-based solar photocatalyst cell - NiOx/ FAPbBr3/TiO2 - for C(sp3)-H bonds activation with high selectivity (~90%) and high conversion rates (3800 μmol g-1 h-1) under ambient conditions. Time-resolved spectroscopy on our photocatalytic cell reveals efficient exciton dissociation and charge separation, where TiO2 and NiOx serve respectively as the electron and hole transporting layers. The photo-generated charge carriers, injected into TiO2 and NiOx drive the challenging C-H activation reaction via the synergetic effects of their band alignment relative to FAPbBr3. The reaction pathway is investigated by controlling the free radical formation and we find that C-H activation is mainly triggered by hole oxidation. Besides aromatic alkanes, also C(sp3)-H bond in cycloalkanes can selectively be oxidised. This work demonstrates a generic strategy for engineering high-performance photocatalysts based on the perovskite solar cell concept.
关键词： photocatalysis,perovskite solar cells,charge separation,C(sp3)-H bond activation,selective oxidation
更新于2025-09-09 09:28:46
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TiO <sub/>2</sub> coating prepared by mechanical alloying treatment for photocatalytic degradation
摘要： In this study, a nanostructured TiO2 coating was successfully prepared on a large-scale titanium plate by a simple one-step surface mechanical alloying (SMA) treatment. The coating was characterised to determine the morphological and composition changes with SMA. The coating was ～60 μm thick and composed of 5 nm diameter rutile TiO2 particles. The photocatalytic activity of the nanostructured TiO2 coating was studied via the ultraviolet–visible (UV–vis) decolorisation of aqueous rhodamine-B. The results showed that the photocatalytic degradation e?ect in 5 h of the f30 mm nanostructured TiO2 coating was comparable to that of 20 mg raw TiO2 under similar UV–visible light irradiation. One-step SMA was demonstrated as an appropriate method to produce a high-performance photocatalytic plate.
关键词： Photocatalysis,black TiO2,organic dye degradation,nanostructured TiO2 coating,surface mechanical alloying
更新于2025-09-09 09:28:46
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Synthesis, Characterization and Photocatalytic Efficiency of ZnO/MWCNT Nanocomposites Prepared Under Different Solvent Conditions
摘要： Here we report the application of zinc oxide (ZnO) coated multi-walled carbon nanotube (MWCNT) composites in the photocatalytic decomposition of acetaldehyde (AA). Zinc oxide nanoparticles were successfully coated on the multi-walled carbon nanotube via impregnation process using zinc acetate (Zn(CH3COO)2 × 2H2O) as precursor and sodium dodecyl sulfate (SDS) treated multi-walled carbon nanotube as raw material under different solvent conditions. The applied solvents during preparation were ethanol (EtOH) and water (H2O). As-prepared materials were characterized by thermal analysis (TG), X-ray diffraction (XRD), specific surface area measurement (BET) and transmission electron microscopy (TEM) techniques. Photocatalytic efficiencies of as-prepared composites were investigated in a stationary reactor equipped with UV lamp. Decomposition of acetaldehyde was followed by using gas chromatography (GC). Observations revealed that using impregnation method and different solvents the preparation of ZnO/MWCNT nanocomposites can be controlled easily. The highest degradation rate was achieved with the nanocomposite was synthetized using ethanol as solvent. The photocatalytic experiments revealed that the composite has higher photocatalytic activity than that of both the zinc oxide nanoparticles and the mechanical mixture of multi-walled carbon nanotube and zinc oxide.
关键词： Transmission Electron Microscopy,Zinc Oxide,Photocatalysis,Gas Chromatography,Nanocomposite
更新于2025-09-09 09:28:46
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Characterization and Photocatalytic Performance of Potassium-Doped Titanium Oxide Nanostructures Prepared via Wet Corrosion of Titanium Microspheres
摘要： Potassium doped titanium oxide (KTiOx) nanowires were prepared by the wet corrosion process (WCP) and their photocatalytic effects were systematically characterized. For the synthesis of KTiOx, the potassium hydroxide concentration of the WCP was varied in order to obtain nanostructures with different surface area and surface charge. Structural and crystalline properties of KTiOx were studied by means of X-ray diffraction, scanning and transmission electron microscopy. Chemical composition was determined by X-ray fluorescence and energy-dispersive X-ray analysis. Photocatalytic performance was investigated as a function of the surface area, pH, and crystalline structures by studying the degradation of methylene blue, cardiogreen, and azorubine red dyes upon UV irradiation. The negatively charged crystalline KTiOx nanostructures with high surface area showed significantly higher photocatalytic degradation compared to their TiOx counterpart. They also showed high efficiency for recovery and re-use. Annealing KTiOx nanostructures improved structural properties leading to well-ordered layered structures and improved photocatalysis. However, annealing at temperatures higher than 600 °C yielded formation of rutile grains at the surface of nanowires, significantly affecting the photocatalytic performance. We believe that KTiOx nanostructures produced by WCP are very promising for photocatalysis, especially due to their high photocatalytic efficiency as well as their potential for re-use and durability.
关键词： Titanium Core Shell,KTiOx,Wet Corrosion Process,Photocatalysis,Nanostructures
更新于2025-09-09 09:28:46
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mpg-C <sub/>3</sub> N <sub/>4</sub> /Ag <sub/>2</sub> O Nanocomposites Photocatalysts with Enhanced Visible-Light Photocatalytic Performance
摘要： To study the photocatalytic activity under visible light irradiation, a series of mesoporous graphitic carbon nitride (mpg-C3N4)/Ag2O photocatalysts were synthesized. The as-prepared photocatalysts were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption Brunauer-Emmett-Teller method (N2-BET), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (DRS), and photoluminescence spectra (PL) methods to determine their phase structure, purity, morphology, spectroscopic and photoluminescence emission performance, respectively. Photocatalytic degradation of methyl orange (MO) aqueous solution under visible-light irradiation indicated that the mpg-C3N4/Ag2O-50 nanocomposite exhibited the best activity. The degradation rate of MO reached to 90.8% in 120 min onto the mpg-C3N4/Ag2O-50 nanocomposite, and as compared with the pure mpg-C3N4 and Ag2O samples, the photocatalytic activity of the mpg-C3N4/Ag2O-50 nanocomposite was greatly enhanced. The enhancement of photocatalytic activity was mainly ascribed to the enhanced visible-light absorption ability and the formation of p–n heterojunctions between counterparts of the nanocomposites, which promoted the generation and separation of charge carriers.
关键词： mpg-C3N4/Ag2O,MO Degradation,Photocatalytic Activity,Visible-Light Photocatalysis,p–n Heterojunctions
更新于2025-09-04 15:30:14
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Iron Oxide Nanoparticles as Potential Scaffold for Photocatalytic and Sensing Applications
摘要： Herein, we report photocatalytic and ?uorescence sensing applications of iron oxide (α-Fe2O3) nanoparticles synthesized by facile low-temperature simple solution process. The synthesized nanoparticles were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) attached with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), UV-visible spectroscopy and ?uorescence spectroscopy. The detailed analysis revealed that the synthesized nanoparticles were well-crystalline, grown in very high density and possessing rhombohedral α-Fe2O3 crystal structure. The prepared nanoparticles were used as ef?cient scaffold for photocatalytic and sensing applications. The detailed photocatalysis results revealed that in presence of an appropriate amount of α-Fe2O3 nanoparticles as photocatalyst, a signi?cant dye degradation of methyl orange (MO) was observed in 140 min. In addition, the fabricated ?orescence sensor based on α-Fe2O3 nanoparticles exhibited a low detection limit of ～3.33 μM/L towards picric acid. The observed results clearly con?rmed that the synthesized α-Fe2O3 nanoparticles are potential scaffold for photocatalysis and sensing applications.
关键词： Picric Acid,Photocatalysis,Methyl Orange,α-Fe2O3 Nanoparticles
更新于2025-09-04 15:30:14