Sutham Niyomwas

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.

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.

Self-Propagating High-Temperature Synthesis of Si-SiC Composite Powder

Silicon-silicon carbide (Si-SiC) composite powders were synthesized by in-situ self- propagating high-temperature synthesis using rice husk ash (RHA)/carbon/Mg as precursors in argon atmosphere. The as-SHS powders were leached by two leaching steps. The microstructure and chemical composition of the obtained Si-SiC composite powders were examined using scanning electron microscope (SEM) and x-ray diffractometer (XRD), respectively.

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.

The Effect of Rotational Speed on Steel Pipe Lined Fe-WB Based Composite Coating by Centrifugal-SHS Process

The Iron-Tungsten boride based composite was coated on the inner surface of steel pipes by centrifugal-self-propagating high-temperature synthesis (centrifugal-SHS) process. The precursors were prepared by a stoichiometric ratio of wolframite mineral (Fe (Mn)WO4), aluminum (Al) and boron oxide (B2O3). Phase composition and microstructure of composite coating were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). On this study, depending on the rotation speed, the highest rotation speed (2250 rpm) produced highest micro-hardness of the composite (1699 HV).

Effect of NaCl on Synthesis of Si-SiC Nanocomposites by Self Propagating High Temperature Synthesis

The Si-SiC nanocomposites have been synthesized by self-propagating high temperature synthesis (SHS) from natural precursors. The effects of difference amount of added NaCl from 0 to 0.75 moles to the reactants on the Si-SiC conversion and particle size were investigated. The reaction were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The nanocomposite results have been characterized by scanning electron microscope, Transmission Electron Microscopy and X-ray diffraction. The results showed that the production of nano-composite materials using SHS process is feasible and agree well with the thermodynamics calculations.

Self-Propagating High-Temperature Synthesis of Fe-W(B, C) Based Composite

Fe-W based composite have successfully been prepared using natural resource. The ferberite (Fe (Mn, Sn)WO4) tailings mixed with aluminum, carbon and boron oxide powder were used as reactants. The reactants were pressed and followed by oxy-acetylene flame ignition. The products from the self-propagating high-temperature synthesis (SHS) reaction were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) couple with dispersive X-ray (EDS).

Effect of Silica Sources on Synthesis of Alumina-Mullite-Silicon Carbide Composite

Synthesis of alumina-mullite-silicon carbide composite (Al2O3-Al6Si2O13-SiCw) was obtained in situ by carbothermal reduction of a mixture of kaolin and two different silica sources. The carbothermal reduction was carried out in a horizontal tube furnace under flow of argon gas. The synthesized products were mixtures of alumina, mullite and silicon carbide in the form of whiskers. The effects of adding two different silica sources of rice husk ash and silica powder to the mixture of kaolin and activated carbon were investigated. XRD and SEM analyses indicate complete reaction of precursors to yield Al2O3-Al6Si2O13-SiC as product powders, with the SiC having whisker morphology.

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.

Influence of Ar Pressure on Product Characteristics of Self-Propagating High-Temperature Synthesis from WO3/B2O3/Al Reactant System

nfluence of Ar gas pressure on the SHS reaction products from WO3/B2O3/Al system has been investigated. The pressure of Ar gas has a significant effect on the phase separation and microstructures of SHS products. Increase in Ar gas pressure has a effect on the phase compositions of SHS products and results in the increase of the amount of W2B. Furthermore, the crystalize sizes of W2B increase with the increase of Ar gas pressure from 0.3 to 0.5 MPa, respectively.