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    Preparation, characterization and photocatalytic properties of rubber-TiO2-rGO composite sheets for dye decomposition in wastewater
    (2017-01-01)
    Tejangkura, Worapol
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    In this work, rubber-TiO<inf>2</inf>-rGO (RT-rGO) composite sheets were successfully prepared by a simple latex mixing-casting method using TiO<inf>2</inf> and natural rubber latex with different amounts of rGO loading. The prepared RT-rGO sheet samples were characterized by XRD, FT-IR, Raman, SEM and EDS techniques. The photocatalytic properties of the prepared RT-rGO sheets as catalyst were evaluated using methylene blue (MB) dye solution under UV light irradiation. The result indicated that all the composite sheets loaded with rGO had better photocatalytic activities than the sheet without rGO loading. RT-rGO6.2% sheet showed the highest removal efficiency of 93.3% which has the rate constant (kapp) as 98.2 times higher than the unloaded sheet. Furthermore, the efficiency of the RT-rGO sheet upon the repeated usage was also studied. The result indicated that the sheet could be easily used, recovered and reused many times with no need for the cleaning in between successive uses. Thus, the RT-rGO sheet appears to be an attractive-material for the wastewater treatment or the water purification industry.
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    Item type:Publication,
    Preparation and photocatalytic activities of tio2-rgo nanocomposite catalysts for mb dye degradation over sunlight irradiation
    (2018-01-01) ; ;
    Tejangkura, Worapol
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    Prasanseang, Warot
    This research aims to investigate photocatalytic activities of titanium dioxide (TiO<inf>2</inf>) incorporated with reduced graphene oxide (rGO) nanocomposite catalysts. These TiO<inf>2</inf>-rGO photocatalysts were easily prepared through a direct-mixing of TiO<inf>2</inf> powder suspended in acidic solution under the different amounts of rGO loading (0.25, 0.50, 0.75 and 1.00 wt%). Then, the obtained TiO<inf>2</inf>-rGO samples were characterized by a several techniques. The results demonstrated that the crystalline phases of all samples are corresponding to pristine TiO<inf>2</inf>, whereas the characteristic peaks of rGO in the TiO<inf>2</inf>-rGO nanocomposites could be observed and also confirmed by Raman spectroscopy. TEM results showed that the TiO<inf>2</inf> nanoparticles were well-combined with rGO nanosheets. Moreover, the photocatalytic activities of all TiO<inf>2</inf>-rGO photocatalyst samples were evaluated by photodegrading of methylene blue (MB) dye solution under natural sunlight irradiation. The results revealed that all TiO<inf>2</inf>-rGO nanocatalysts exhibited much higher activity than those of the bare TiO<inf>2</inf>. The improved photocatalytic activity can be attributed to the presence of rGO nanosheets, leading to the decrease of electron (e<sup>-</sup>)-hole (h<sup>+</sup>) recombination of TiO<inf>2</inf> catalyst, increasing charge transfer rate of electrons and surface-adsorbed amount of MB molecules which enhances the photocatalytic activity.
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    Investigation of the influences of reaction temperature and time on the chemical reduction of graphene oxide by conventional method using Vitamin C as a reducing agent
    (2017-01-01) ; ;
    Kongtaweelert, Samart
    The aim of this work is to investigate the synthesis of reduced graphene oxide (rGO) aqueous suspension by a conventional heating method using vitamin C as a reducing agent. The influences of reaction temperatures (70, 90 and 100 °C) and heating times (30, 45 and 60 min) on the chemical reduction of graphene oxide (GO) were studied. Then, the obtained rGO samples were characterized by FT-IR, Raman, UV-Vis, XRD and TEM techniques. The FT-IR and Raman results showed that the reduction degree of GO to rGO was increased with the rising of the reaction temperature and time. Moreover, the UV-Vis spectra demonstrated that the absorption band at around 230 nm (π-π*) of pristine GO had shift to the longer wavelength upon the chemical reduction, indicating that GO is reduced to rGO. The optimal condition of the chemical reduction of GO to achievable rGO was the temperature of 90 °C with the 45 min of heating time. This condition yielded the rGO black aqueous suspension with the high quality and stability. Thus, this method of synthesis has an advantage of the rGO dispersion which led to many potential applications.