Lek Sikong

Photocatalytic Antibacterial Performance of Glass Fibers Thin Film Coated with N-Doped SnO2/TiO2

Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600°C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency.

Facile preparation of magnetic C/TiO2/Ni composites and their photocatalytic performance for removal of a dye from water under UV light irradiation.

Development of a photocatalyst with high efficiency and separability is still a challenging task in the field of wastewater treatment. In this study, new magnetic separable C/TiO2/Ni composite as a photocatalyst was prepared by a facile pyrolysis reaction, using powdered activated carbon (PAC), TiO2 and Ni(Ac)2 as precursors. The results proved that the photocatalyst (C/TiO2/Ni) synthesized in this work exhibited greater removal activity for Methyl Orange (MO) dye from water as compared with the commercially available well reported TiO2 nanoparticles (P25). This significant enhancement in the photocatalytic activity for wastewater treatment due to the combination of PAC and TiO2 could be presumed as the synergetic effect on the contacting interface of TiO2 and PAC, and such effect was initially demonstrated by electrochemical impedance measurements. Furthermore, the trait that it consists of magnetic properties and therefore is easy to be recycled, which could be harnessed by an external magnet and may have many advantages over pure metal oxides (like TiO2) especially in the industrial procedures.

Photocatalytic Degradation of Glyphosate in Water by N‐Doped SnO2/TiO2 Thin‐Film‐Coated Glass Fibers

Photocatalytic degradation of glyphosate contaminated in water was investigated. The N‐doped SnO2/TiO2 films were prepared via sol–gel method, and coated on glass fibers by dipping method. The effects of nitrogen doping on coating morphology, physical properties and glyphosate degradation rates were experimentally determined. Main variable was the concentration of nitrogen doping in range 0–40 mol%. Nitrogen doping results in shifting the absorption wavelengths and narrowing the band gap energy those lead to enhancement of photocatalytic performance. The near optimal 20N/SnO2/TiO2 composite thin film exhibited about two‐ and four‐folds of glyphosate degradation rates compared to the undoped SnO2/TiO2 and TiO2 films when photocatalytic treatment were performed under UV and solar irradiations, respectively, due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and smallest crystallite size influenced by N‐doping.

P. aeruginosa Inactivation with Silver and Nickel Doped TiO2 Film Coat on Glass Fiber Riving

The photocatalytic Ag and Ni doped TiO2 films were prepared by sol-gel method and coated on glass fiber roving. The films were calcined at 500 °C for 1 hour with a heating rate of 10°C/min. The surface morphology and properties of synthesized TiO2 films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and UV-vis diffuse reflectance spectroscopy (DRS). The results show that TiO2-1Ag and TiO2-1Ag-1Ni films give rapidly kill P.aeruginosa bacteria under UV irradiation and TiO2-1Ni films give well kill P.aeruginosa bacteria under visible light.

Phase transformation of VO2 nanoparticles assisted by microwave heating.

The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2 (M) was prepared from NH4VO3 and H2C2O4 · 2H2O by a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180–600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties.

Antibacterial Activity of TiO2 and Fe3+ Doped TiO2 Nanoparticles Synthesized at Low Temperature

Nanocrystalline TiO2 powder with and without Fe3+ doping were successfully synthesized at low temperature by a microwave-assisted sol–gel method. The synthesized TiO2 powders were characterized by XRD, BET, FT-IR and SEM. It was found that anatase phase was formed after refluxed at 80°C using a domestic microwave oven. Antibacterial behavior towards E. coli was then studied under UV and fluorescent irradiation. The synthesized pure TiO2 powder exhibited superior antibacterial activity under fluorescent irradiation compared to the commercial TiO2 (Degussa P25). It can efficiently destroy E. coli bacteria after 20 min with UV irradiation and 3 h with fluorescent light; this good activity is mainly related to the high OH radicals on its surface. It was also observed that the synthesized powders have smaller crystallite size and larger specific surface area than those of Degussa P25 due to the absence of high temperature calcination requirement.

Inactivation of Salmonella typhi Using Fe3+ Doped TiO2/3SnO2 Photocatalytic Powders and Films

The aim of the present study is to synthesize Fe3+-doped TiO2/3SnO2 powder and evaluate its antibacterial performance coated on polyvinylchloride films for fresh food packaging. Fe3+-doped TiO2/3SnO2 nanoparticles were prepared as a photocatalyst through the sol-gel method with concentrations of 0.3-1.2 mol% and a calcination temperature of 400°C. It was found that calcination temperatures strongly affect the phases and phase transformation of TiO2. According to XRD analysis, the anatase crystalline was formed at the calcination temperature of 400°C. In the present work, the photocatalytic performance was determined through methylene blue degradation. The antibacterial activity against Salmonella typhi was investigated with a vitro test, from which the mixture of conidial suspension and Fe3+-doped TiO2/3SnO2 powder was added to Nutrient agar (NA) plates under UV and visible light irradiation, respectively. It was found that Fe3+-doped TiO2/3SnO2 nanoparticles enhance photocatalytic activity and bacterial inactivation efficiency. In addition, Fe3+-doped TiO2/3SnO2 thin films can destroy the cell walls of bacteria within 240 min. Furthermore, the disinfection efficiency of TiO2/3SnO2/0.5 Fe3+ is greater under UV irradiation than it is under visible light.

The Effect of Molar Ratio of TiO2/WO3 Nanocomposites on Visible Light Prepared by Hydrothermal Method

The coupled TiO2/WO3 nanocomposites were synthesized by hydrothermal method by using hydrogen titanate and ammonium metatungstate hydrate as the precursors of TiO2 and WO3, respectively. The effects of hydrothermal conditions to prepare hydrogen titanate powders were studied. It was found that the hydrothermal condition at 130 °C for 24h shown the best result. The TiO2/WO3 nanocomposites were carried out as a function of varied molar ratio of TiO2/WO3 for 1:1, 3:1 and 1:3. The coupled TiO2/WO3 nanocomposites are characterized by transmission electron microscopy, UV-vis absorption spectra by UV–VIS spectrometer and photocatalytic activity by degradation of MB solution under visible light. The results show that the absorption spectra of the coupled TiO2/WO3 nanocomposites can be seen in visible light region which higher than pure TiO2 (from hydrothermal method) and P25-Degussa.

Photocatalytic Activity against Penicillium Expansum of Ag-Doped TiO2/SnO2/SiO2

The effect of 0.1-1 mol%Ag doping on crystallite size, morphology, photocatalytic and fungal growth suppression activities of TiO2/SnO2/SiO2 nano-composite powders were investigated. The powder was synthesized by sol-gel method and studied for physicochemical properties by XRD, spectrometric techniques, FTIR, SEM, EDX and BET. The anatase structure was formed after calcination at 500oC. Photocatalytic activities towards Penicillium expansum growth suppression correlated to the amount of sliver doped in TiO2/SnO2/SiO2 nano-composite powder under ultraviolet radiation. Ag 1.0mol% doped in TiO2/SiO2/SnO2 composite has a significant effect on antifungal behaviour. It could completely kill Penicillium expansum within one day of photacatalytic treatment under UV irradiation.

Enhanced Photocatalytic Degradation of Fulvic Acid Using N–Doped SnO2/TiO2 Thin Film Coated Glass Fibers under UV and Solar Light Irradiation for Drinking Water Purification

The degradation of fulvic acid (FA) using N–doped SnO2/TiO2 composite thin films coated on glass fibers prepared by sol–gel and dip–coating methods was investigated. The effects of nitrogen doping on coating morphology, physical properties, and FA degradation rates were experimentally determined. Nitrogen doping has an effect on shifting the optical absorption wavelength to visible light region, narrowing the band gap energy and reducing crystallite size which lead to the enhancement of photocatalytic performance. The optimal FA degradation rates of 40N/SnO2/TiO2 composite thin films under UV and solar irradiation are about 2.4 and 2.0 folds higher than that of TiO2 film, respectively due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and small crystallite size influenced by nitrogen doped.