研究目的
Investigating the photocatalytic degradation kinetics of gaseous formaldehyde using TiO2 nanowires under UV irradiation, focusing on reaction kinetics, factors affecting degradation rate, and catalyst performance.
研究成果
TiO2 nanowires prepared by hydrothermal method exhibit high photocatalytic activity for formaldehyde degradation under UV light, with kinetics following the LHHW model but not first-order. Degradation rate is influenced by light intensity, flow rate, and catalyst properties. The catalyst shows good stability over time. Future work should explore visible light activation and practical application scaling.
研究不足
The study is limited to UV irradiation (365 nm) and may not be efficient under visible light. The homemade reactor setup might not be scalable for industrial applications. The kinetic model assumes specific adsorption conditions that may not hold in all environments. Potential optimizations include extending to visible light catalysts and improving reactor design for higher flow rates.
1：Experimental Design and Method Selection:
The study involved synthesizing TiO2 nanowires via a hydrothermal method to enhance surface area and active sites for photocatalytic efficiency. A homemade tube reactor was used for real-time monitoring of formaldehyde degradation under UV LED irradiation. The Langmuir-Hinshelwood-Hougen-Watson (LHHW) model was applied for kinetic analysis.
2：Sample Selection and Data Sources:
TiO2 nanowires were prepared from titanium(IV) oxide (P25) and annealed at different temperatures (600°C, 650°C, 700°C). Formaldehyde gas at low concentration (0.5 mg/m3) was used as the pollutant source.
3：5 mg/m3) was used as the pollutant source. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included a hydrothermal reactor, ultrasonic stirrer, X-ray diffractometer (XRD, Shimadzu XRD7000), transmission electron microscope (TEM, Libra 200FE, Zeiss), field emission scanning electron microscope (FESEM, JSM-7800F10100), X-ray photoelectron spectrometer (XPS, VG ESCALAB 250), Fourier transform infrared spectrometer (FTIR, Perkin Elmer Frontier), UV-Vis-NIR spectrophotometer (Agilent Cary 5000), photoluminescence spectrometer (PL, Hitachi F-7000), nitrogen adsorption apparatus (Quadrasorbevo 2QDS-MP-30), electrochemical workstation (AUTOLAB PGSTAT 302N), gas chromatography (GC-2018, Shimadzu), and UV LED lamps (365 nm). Materials included titanium(IV) oxide (Aeroxide P25), NaOH, HCl, formaldehyde gas, and asbestos fiber.
4：Experimental Procedures and Operational Workflow:
TiO2 nanowires were synthesized hydrothermally, washed, annealed, and characterized. Photocatalytic degradation tests were conducted in a quartz tube reactor with controlled flow rates and light intensities. Formaldehyde concentration was monitored before and after degradation using gas chromatography.
5：Data Analysis Methods:
Kinetic data were fitted to the LHHW model. Statistical analysis included linear fitting for reaction order determination. Software tools for instrument operation and data processing were not specified.
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X-ray diffractometer
XRD7000
Shimadzu
Analyzing the crystal structure of TiO2 nanowires using Cu Kα irradiation.
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Transmission electron microscope
Libra 200FE
Zeiss
Characterizing the morphology and lattice fringes of TiO2 nanowires.
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Fourier transform infrared spectrometer
Frontier
Perkin Elmer
Analyzing the vibration state of chemical bonds in TiO2 nanowires using KBr pellets.
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UV-Vis-NIR spectrophotometer
Cary 5000
Agilent
Obtaining UV-Vis diffuse reflection spectra of TiO2 nanowires.
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Photoluminescence spectrometer
F-7000
Hitachi
Measuring photoluminescence spectra of TiO2 nanowires with xenon light excitation.
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Electrochemical workstation
PGSTAT 302N
AUTOLAB
Carrying out electrochemical tests in a three-electrode system for photocurrent response and impedance.
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Gas chromatography
GC-2018
Shimadzu
Monitoring formaldehyde concentration in the gas path using molecular sieve columns and TCD detector.
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Field emission scanning electron microscope
JSM-7800F10100
Characterizing the surface morphology of TiO2 nanowires.
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X-ray photoelectron spectrometer
VG ESCALAB 250
Analyzing the chemical state and composition of TiO2 nanowires using Al Kα radiation.
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Nitrogen adsorption apparatus
Quadrasorbevo 2QDS-MP-30
Conducting nitrogen adsorption-desorption isotherms at 77 K to characterize specific surface area and pore size.
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UV LED lamp
Irradiating the photocatalyst with 365 nm light for photocatalytic degradation.
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Titanium(IV) oxide
Aeroxide P25
Used as a precursor for synthesizing TiO2 nanowires.
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