Papers by Author: Chamorn Chawengkijwanich

Abstract: This study aims to provide the photocatalytic approach for treatment of some hazard air pollutants such as benzene, toluene, ethylbenzene and xylene (BTEX) under visible light. Silver doped titanium dioxide (Ag/TiO₂) thin films with various molar ratios (0.01, 0.05, 0.1 and 0.2 mol) were synthesized via sol-gel method and dipped on polyvinyl chloride (PVC) sheet before curing with UV lamp. The X-ray diffractograms showed the composite of TiO₂ anatase and nanosilver. The effect of silver doping on decreasing of band gap energy of TiO₂ was observed from the absorption edge shift to higher wave length, analyzed by UV-visible spectrometer. The results from hydrophilicity test indicated that hydrophilicity of TiO₂ thin film was increased by doping silver. The morphology of the Ag/TiO₂ thin film studied by Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer revealed well dispersed nanosilver on the smooth thin film. The BTEX degradation was carried out in a batch reactor with the initial concentration of mixed BTEX gas [25 ppm]. The remaining BTEX was examined by Gas Chromatography equipped with flame ionization detector. Among Ag/TiO₂ thin films, the 0.1 Ag/TiO₂ thin films exhibited the best performance for gaseous BTEX degradation under visible light. The maximum degradation efficiency was belong to xylene (89%), followed by ethylbenzene (86%), toluene (83%) and benzene (79%).

Abstract: In this work, TiO₂ thin films were deposited on borosilicate glass substrates by sol-gel dip coating method and calcined at 500 °C for 15 min(heating rate3°C /min). The TiO₂ sol was prepared by fixing concentration of titaniumtetraisopropoxide(TTIP), TritonX-100 surfactant, ethanol and conc hydrochloric acid but amounts of acetyl acetone (Acac ) were various as 4, 6 and 8 mole respectively. After calcination process, all the TiO₂ thin films were homogeneous and transparent. Several techniques , such as X-ray diffraction (XRD), UV-Vis spectroscopy, Environment Scanning Electron Microscope (E-SEM), atomic force microscopy (AFM) and BET surface area analysis were used to characterize the prepared TiO₂ thin film. Spectra of XRD showed that the crystal structure was anatase phase with the crystal sizes of 9.05 – 12.57 nm. According to BET surface area analysis, the surface area , pore volume and pore size of TiO₂ were in the range of 66.35-82.53 m²/gm , 0.1194-0.1301 cm³/g and 57-71 A⁰ respectively. The photodegradation of Reactive Blue 19 by the prepared TiO₂ thin films showed decomposition rate of 97.58% , 95.03 % and 94.48% for the thin films prepared by using 4, 6 and 8 mole AcAc respectively.

Abstract: Dipping borosilicate glass in modified sol-gel solution was used to prepare thin film TiO₂. The sol was prepared from titaniumtetraisopropoxide(TTIP), hydrochloric acid (conc. HCl), ethanol(EtOH), TritonX-100 surfactant and acetic acid(AcOH). The mole ratios of the starting solution were surfactant: EtOH: AcOH: TTIP: conc.HCl= R: 45: 6: 1: 0.1. The amounts of surfactant (R value) were varied as 0, 0.5, 1, 2, 3 and 4 moles, respectively. After dip-coated, the borosilicate glasses were dried at room temperature and heated for 15 minutes at 500 ^°C (rate3^°C/min). The obtained films were uniform; however, varied in transparency, decreasing when the TritonX-100/TTIP mole ratios had been increased. The crystal structure, optical property and the morphology of thin films TiO₂ were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, Environment Scanning Electron Microscope (E-SEM) and Atomic Force Microscopy (AFM). Spectra of XRD showed that all the TiO₂ thin films were anatase phase. From UV–Vis technique, it was found that their UV absorption edges were approximately 380 nm. A cracking on the surface of TiO₂ thin films appeared when the amounts of the surfactant were increased. From AFM image, TiO₂ particles were spherical size, ranged from 11.2 to 35.5 nm and the roughness of the films increased with the increasing of TritonX-100/TTIP mole ratios. Under UV illumination, the photodegradation results of Reactive Yellow17 was pseudo the first order reaction and the film of TritonX-100/TTIP mole ratio = 1 : 1 was the highest removal efficiency with the apparent rate constant (k) = 2x10^-2 min^-1 and half life (t_1/2) = 34.65 min.