Papers by Keyword: Photocatalytic Oxidation

Abstract: Design and development of nanostructure of titanium dioxide (TiO₂) assemblies has gained significant scientific interest and become the most studied material as it exhibits promising functional properties. Nevertheless, formation of TiO₂ nanocomposite thin film, especially WO₃-loaded TiO₂ nanotubes without bundling is essential for high efficiency in many potential applications, including photocatalytic oxidation related applications, solar cell related applications, electrochromic devices and sensing related applications. Thus, this chapter aims to summarize on the development of an efficient WO₃-loaded TiO₂ nanotubes catalyst for the improving the performance for charge carriers transportation and extended the spectral response of TiO₂ to visible spectrum. In fact, coupling TiO₂ with W⁶⁺ species will lead to an additional electronic state in the band-gap of nanocomposite thin film, which in turn affect a change in the electronic and functionality of TiO₂ itself. As a result, band gap narrowing effects could expand the range of excitation light to the visible region and provide sites that slow down the recombination of charge carriers. To bring more TiO₂ related applications to the point of commercial readiness and viability in terms of performance and cost, substantial research on the development of high efficient nanocomposite thin film (WO₃-TiO₂) is necessary. In this chapter, different synthesis strategies and research findings for WO₃-TiO₂ nanocomposite thin film as well as its prospects in potential applications will be reviewed in detail.

Abstract: Carbon nitride is a representative metal-free photocatalyst for green chemical technology. In this study, synthesized g-C₃N₄ carbon nitride was employed to study effect of pH and potassium salt loading on photocatalytic oxidation of benzyl alcohol. The result indicated that the maximum conversion could be achieved to 20.75% at a pH of 8.66 with a concentration of K₂HPO₄ of 0.6 mmol Suitable pH and salt concentration were important factor for promoting of proton on surface and electronic conductivity to separate electron in photocatalysis.

Abstract: Visible light responsive CoTiO₃ nanoparticles with average diameter of 100 nm were successfully synthesized by sol-gel method and were firstly applied to catalytic activation of peroxymonosulfate (PMS) for degradation of organic pollutants (Rhodamine B (RhB)). Photocatalytic experiments illustrated that CoTiO₃ nanoparticles reveal good photocatalytic activity and excellent ability to activate PMS, the synergistic effect of visible light photocatalysis and sulfate radical generated from activated PMS can degradate RhB efficiently. Besides, CoTiO₃ nanoparticles maintain their high photocatalytic and activation efficiency after three times recycling.

Abstract: Titania (TiO₂) nanotubes were successfully synthesized via a facile hydrothermal method. The influence of starting material (TiO₂ nanoparticles) content on the conversion of tubular structure during hydrothermal treatment was investigated. Based on the result obtained, it was found minimum 1 g of TiO₂ nanoparticles was required for completing the transformation of nanotubular structure. The photocatalytic activity of TiO₂ nanotubes was evaluated by degradation of organic methyl orange (MO) dye. Interestingly, one-dimensional TiO₂ nanotubes exhibited high photocatalytic oxidation rate (78% degradation) under UV irradiation for 5 hours. The reason was attributed to the high active surface area to generate more hydroxyl radicals (∙OH) for triggering photocatalytic oxidation reactions on the inner and outer surface of TiO₂ nanotubular structure.

Abstract: A supported photocatalyst zinc phthalocyanine-calcium alginate gel beads (Zn-MPc-SA) was prepared through the mixture of water-soluble zinc phthalocyanine (Zn-MPc) and sodium alginate was drip into 5% (w/v) CaCl₂ solution. The Zn-MPc-SA was characterized by IR. Methyl orange was selected as a substrate to investigate the photocatalytic activity of Zn-MPc-SA. The results shown that: the surplus of methyl orange was 22.05% at the condition of pH 3, methyl orange 10mg/L 25mL, H₂O₂ 50μL, Zn-MPc-SA 0.1460g and visible light irradiation for 3h. Zn-MPc-SA remains efficient in repetitive test cycles with no obvious degradation of catalytic activity. The reaction mechanism was likely to involve free hydroxyl radicals.

Abstract: Based on phthalocyanines --SnO₂ as a photo catalyst, this paper uses the degrading difference of thiophene by various catalysts under ultraviolet and visible light irradiation conditions to compare the catalytic effects of the different phthalocyanine compounds --SnO₂ photosensitive catalysts, and summarize the reasons and laws to influence the catalysts’ catalytic performance, and analyze the kinetic process of photocatalytic oxidation reaction, and initially discuss kinetics of photocatalytic oxidation reaction and its products.

Abstract: The potential hazard effects of Endocrine Disruptors (EDCs) are drawing growing attention from the public,and the traditional sewage water treat process works in an unstable way in the removal of EDCs and can be influenced by many factors.The membrane technology shows good interception efficiency of EDCs,and the photocatalytic oxidation,with its wide application range of different types of polluted water,can thoroughly convert EDCs to inorganic materials.The combination process of nanofiltration and photocatalytic oxidation can easily extract EDCs from the water at first step,and decompose the EDCs in the concentrated polluted water and the back fluch water collected at the second step.The combination process is a reliable,practical and effective methods for EDCs removal.

Abstract: Titanium dioxide with coupling agent (ETES) was applied as a photocatalyst for a synthesis of the TiO₂/LDPE composite film. The physical properties of TiO₂/LDPE composite film were analyzed by a Scanning Electron Microscope (SEM). TiO₂ particles were impregnated into the polymer matrix film as a LDPE composite film. The results from the X-ray Diffraction (XRD) technique revealed that the structure of TiO₂/LDPE composite film were anatase crystalline. The chemical structure of the TiO₂/ LDPE composite films were analyzed by an ATR-Fourier transforms infrared (ATR-FTIR) spectrometer. Wavenumber of FTIR spectra at 719 cm¹ indicated the Ti-O-Ti bond. Band gap energies of the films ranged from 3.19-3.29 eV. The photocatalytic activity of the film was tested for removal of gaseous acetone in a closed chamber. Experimental conditions were set as follows: a UV light intensity of approximately 2.7 mW.cm^-2, flow rate of 2 L.min^-1, and an initial acetone concentration of about 435±20 ppm. While the catalyst dosage was varied from 3% to 15% (wt. cat/wt. film).The degradation rate of acetone increased when increasing dosage of TiO₂ from 3% to 10%, then decreased a little bit when increasing the dosage to 15%. The TiO₂/LDPE composite film at the dosage of 10% yielded the highest removal efficiency of 75%, followed by the film at the dosage of 15%, 5%, and 3%, respectively.

Abstract: This research aimed to apply the Blown Film Extrusion technique to synthesize the titanium dioxide (TiO₂) bio-composite films incorporated on a thin film as a photocatalyst. The biopolymer materials have great recognition via their renewable and biodegradable characteristic and the green composite has been a new challenge path to replace traditional polymer composite. In this work, TiO₂/Polybutylene succinate (PBS) bio-composite film was developed to be used as a supporter for determining the photocatalytic oxidation activity of the TiO₂ on the chlorinated volatile organic compounds degradation. PBS is a synthetic biopolymer which has a reasonable mechanical strength. The modified-TiO₂/PBS bio-composite films were studied to evaluate the degradation of dichloromethane. In order to improve the distribution of the developed photocatalyst, the TiO₂ powders were modified by 0.05% mole of ethyl triethoxysilane (ETES) and stearic acid (SA), respectively. The 10% wt. TiO₂/PBS bio-composite films with thickness of 30 μm were prepared by blown film technique. To evaluate the dispersion efficacy, the modified-TiO₂/PBS bio-composite films were characterized by Scanning Electron microscopy (SEM). Photocatalytic degradation of dichloromethane in gas phase was determined using an annular closed system photoreactor. The obtained result which was corresponding to the absorption of TiO₂/PBS bio composites film was investigated in a range of 300-400 nm via UV/VIS spectrophotometry. The energy band gap of TiO₂, ethyl triethoxysilane-TiO₂ and stearic acid-TiO₂ bio-composite film was found to be 3.18, 3.21, and 3.26 eV, respectively. The SEM shows that the modified-TiO₂ with both ETES and SA exhibit uniform dispersion, while the only TiO₂ shows an evidence of agglomeration in the PBS matrix. For photocatalyst efficiency, the photocatalytic activity of modified-TiO₂/PBS bio-composite film increased comparing to the TiO₂/PBS bio-composite film. Moreover, the photocatalytic degradation of dichloromethane by ETES-TiO₂/PBS bio-composite film yielded degradation efficiency of 47.0%, whereas SA-TiO₂/PBS bio-composite film yielded the removal efficiency of 41.0% for detention time at 350 min.

Abstract: The sol-gel method is adopted in this study to prepare the TiO₂-composite semiconductor materials doped with ZnO, whose crystal structures are characterized by way of X-ray diffraction and Transmission Electron Microscopy (TEM). It is concluded that the optimal doping amounts of Zn and lanthanum and the calcination temperature are respectively 3%, 0.3% and 500°C. Mixed with water, the photocatalytic oxidation effects of reactive brilliant blue X-BR, taken as the degradation target, was investigated in this study. When the doping amount of lanthanum is 0.3%, the chroma removal rate of the reactive brilliant blue X-BR by lanthanum-modified ZnO-TiO₂ can reach 97.3%. The conditions for optimal decolorization rate are: under ultraviolet light for 2h, using the 100mg / L reactive dyes, controlling pH at about 1 and the chloride concentration at 1mol / L.