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    X-ray characterization, structural analysis, antibacterial activity, and self-cleaning property of Cu-doped TiO2-SiO2 nanocomposite prepared by sonochemical process
    (2024-12-01) ;
    Songpanit, Maneerat
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    Sanyen, Thanyapa
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    Samart, Sutichai
    ;
    TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposites with different copper (Cu) precursor loadings were prepared by a one-step sonochemical process. The mole ratio of Cu precursor in TiO<inf>2</inf>-SiO<inf>2</inf> composite was varied at 0.004, 0.008, 0.020, and 0.040, respectively. The specific X-ray characterization techniques on crystalline structure, chemical composition, and chemical states of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite were carried out by X-ray diffraction technique (XRD), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS), respectively. Surface morphology and chemical bonding of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite were monitored by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectrophotometer (FTIR). For antibacterial properties, the inhibition zone of antimicrobial activity was investigated by varying amounts of Cu precursors in the TiO<inf>2</inf>-SiO<inf>2</inf> composite. After that, Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite powder with different Cu precursor ratios was mixed in PMMA solution and deposited on glass slides to study the optical property and hydrophilicity by UV-VIS-NIR spectrophotometer and contact angle method. XRD patterns of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposites show the formation of the main TiO<inf>2</inf> anatase phase with the ultrafine particles observed by FE-SEM images. FT-IR spectra of the composites are assigned to the prominent peaks of the Ti-O-Ti and Ti-O-Si bond relating to the TiO<inf>2</inf>-SiO<inf>2</inf> host matrix. Meanwhile, TiO<inf>2</inf>-SiO<inf>2</inf> composites with Cu precursor at 0.004 mol ratio can significantly enhance the antibacterial activity with a large inhibition zone. The contact angle value of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposite film at 0.040 Cu precursor mole ratio in the TiO<inf>2</inf>-SiO<inf>2</inf> matrix resulted in the optimized composite ratio for achieving a hydrophilic surface on the substrate.
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    ZnO nanostructures synthesized by one-step sol-gel process using different zinc precursors
    (2024-01-01)
    SONGPANIT, Maneerat
    ;
    ; ;
    Zinc oxide (ZnO) nanopowders have been widely applied in electronics, optics and photocatalytic applications depending on their morphological structure. In the bottom-up process, it is conceived that the different zinc precursors may result in different formations of ZnO nanostructures with exceptional morphology. This work focuses on ZnO material synthesized via the facile sol-gel synthesis using different zinc slat precursors, including zinc acetate, zinc nitrate, zinc sulphate, and zinc chloride. All zinc salt precursors were incorporated with sodium hydroxide and hexamethylenetetramine (HMTA) under mild thermal energy with consistent conditions to investigate ZnO formation. The as-prepared samples appeared in white powders with different aggregation features. The crystalline phase, surface morphologies, and element mapping of all ZnO samples were analyzed using X-ray diffraction technique (XRD) and field emission scanning electron microscope (FE-SEM). The chemical bonding structure of ZnO powders was characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The specific surface area per volume of ZnO nanopowders obtained by different zinc salt precursors was analyzed by Brunauer-Emmett-Teller (BET) method. All ZnO samples obtained from various zinc salt precursors exhibited a high crystallinity of the wurtzite structure without other impurities. The structural properties of ZnO nanopowders demonstrated different sizes and structures with distinguished formation and aggregation depending on the zinc precursor basic strength being used.
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    Characterization and x-ray absorption spectroscopy of ilmenite nanoparticles derived from natural ilmenite ore via acidassisted mechanical ball-milling process
    (2017-09-01)
    Phoohinkong, Weerachon
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    Pavasupree, Sorapong
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    Wannagon, Anucha
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    Sanguanpak, Samunya
    ;
    In this work activated ilmenite nanoparticles were prepared by chemical-assisted in mechanical ball-milling process from ilmenite ore as starting raw material. The effect of milling process on their phase composition, particle size, surface morphology and local structure were investigated. Phase identification and crystalline structure of ilmenite mineral, milled samples and subsequent leached residues were characterized by x-ray diffraction (XRD). Meanwhile, the distorted octahedral structure and the oxidation state of relevant elements in ilmenite ore and activated ilmenite obtained by different process conditions were analyzed by x-ray absorption spectroscopy (XAS). Particle size and morphologies of the samples were monitored by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Three dominant peaks of TiO2 rutile, FeTiO<inf>3</inf>, and Fe<inf>2</inf>TiO<inf>4</inf> are obviously adulterated in XRD patterns after mechanical milling with water and acid solution when comparing to precursor mineral. However, the contaminated phase of FeTiO3 and Fe<inf>2</inf>TiO<inf>4</inf> was readily decreased by acid-assisted mechanical ball-milling. The enhancement in leaching process of ilmenite residue after milling can be obtained with sulfuric acid. This result suggests that iron contaminated phase could be leached from the sample resulting to the decrease in Fe environment around Ti atom.
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    Glucose Conversion to 5-(Hydroxymethyl)furfural (5-HMF) using Microwave Radiation and Titanium Dioxide
    (2022-01-01) ; ;
    Boonyarattanakalin, Siwarutt
    ;
    In this project, the focus is placed on the reaction optimizations to produce 5-hydroxymethylfurfural (5-HMF), a common chemical building block to other industrially useful derivatives. The main objective of this study is to determine the feasibility of using different forms of TiO<inf>2</inf> as a catalyst to acquire 5-HMF from monosaccharides by an efficient, economical, and environment-friendly process. The use of three different forms of TiO<inf>2</inf> (anatase, rutile, and P-25) as a catalyst, for the glucose dehydration process in this study, has never been reported in past literature. The heating by microwave radiation is introduced to the reaction, which requires elevated temperature, to reduce both the required reaction time and temperature. TiO<inf>2</inf>, the heterogeneous catalyst for the dehydration mechanism, was filtered off, while the 5-HMF dissolved and stayed in the aqueous solution. The three TiO<inf>2</inf> catalyst forms are separately utilized to optimize reaction conditions. Anatase form is shown to be the most effective at catalyzing the dehydration process. The reaction temperature of 187 ºC; anatase as a catalyst; and reaction time of 5 minutes led to the optimal outcome in this project. The maximum 5-HMF yield obtained in this study is 12.84%, which is in-between the 6.10-18.60% 5-HMF yield range acquired by Qi et al., 2008. Moreover, a catalyst/substrate weight ratio of 1:10 was used in this study, compared to the 1:2 ratio used by Qi et al., 2008. Hence, this project reduced the amount of catalyst required to obtain a significant 5-HMF yield, and successfully demonstrated that the anatase form of TiO<inf>2</inf> is a viable catalyst for the dehydration of monosaccharides to 5-HMF.
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    The Effect of Polyvinyl Alcohol Addition on the Optical Properties and Oxygen Detection Performance of Titanium Dioxide and Methylene Blue Nanocomposite Colorimetric Indicators
    (2024-05-01) ;
    Rattan, Praphaporn
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    Songpanit, Maneerat
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    Okumura, Hideyuki
    In this study, we investigated the impact of polyvinyl alcohol (PVA) incorporation on the optical properties and oxygen detection performance of a titanium dioxide/methylene blue (TiO<inf>2</inf>/MB) nanocomposite colorimetric indicator for packaging applications. The nanocomposite was synthesized via mechanical milling of TiO<inf>2</inf> nanoparticles with MB and citric acid. PVA, at varying concentrations (0, 3, 9, and 14 wt%), was introduced during the wet milling process to produce a homogeneous composite film. Spin coating was employed to fabricate TiO<inf>2</inf>/MB nanocomposite films for oxygen detection evaluation. The influence of PVA loading on the films’ chemical functionalities and surface morphologies was assessed using Fourier-transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FE-SEM). The indicator’s activation process, involving a color change between bleached and colored states, and its recovery time were monitored via optical imaging and UV-VIS-NIR spectrophotometry. The results revealed that a PVA content of 9 wt% yielded well-defined films with enhanced stability of the TiO<inf>2</inf>/MB nanocomposite’s oxygen detection performance.
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    Tailoring the Emission Behavior of WO3 Thin Films by Eu3+ Ions for Light-Emitting Applications
    (2023-01-01)
    Kavitha, V. S.
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    Biju, V.
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    Gopchandran, K. G.
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    Praveena, R.
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    Jayasankar, C. K.
    The article reports the successful fabrication of Eu<sup>3+</sup>-doped WO<inf>3</inf> thin films via the radio-frequency magnetron sputtering (RFMS) technique. To our knowledge, this is the first study showing the tunable visible emission (blue to bluish red) from a WO<inf>3</inf>:Eu<sup>3+</sup> thin film system using RFMS. X-ray diffractograms revealed that the crystalline nature of these thin films increased upto 3 wt% of the Eu<sup>3+</sup> concentration. The diffraction peaks in the crystalline films are matched well with the monoclinic crystalline phase of WO<inf>3</inf>, but for all the films’, micro-Raman spectra detected bands related to WO<inf>3</inf> monoclinic phase. Vibrational and surface studies reveal the amorphous/semi-crystalline behavior of the 10 wt% Eu<sup>3+</sup>-doped sample. Valence state determination shows the trivalent state of Eu ions in doped films. In the 400–900 nm regions, the fabricated thin films show an average optical transparency of ~51–85%. Moreover, the band gap energy gradually reduces from 2.95 to 2.49 eV, with an enhancement of the Eu<sup>3+</sup>-doping content. The doped films, except the one at a higher doping concentration (10 wt%), show unique emissions of Eu<sup>3+</sup> ions, besides the band edge emission of WO<inf>3</inf>. With an enhancement of the Eu<sup>3+</sup> content, the concentration quenching process of the Eu<sup>3+</sup> ions’ emission intensities is visible. The variation in CIE chromaticity coordinates suggest that the overall emission color can be altered from blue to bluish red by changing the Eu<sup>3+</sup> ion concentration.
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    Effect of Hexamethylenetetramine on Physical, Structural, and Photocatalytic Properties of ZnO Nanostructures Synthesized via One-Step Sol-Gel Process
    (2026-07-01)
    Songpanit, Maneerat
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    Basu, Soumya
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    Okumura, Hideyuki
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    Ishihara, Keiichi N.
    Wastewater contamination with synthetic organic dyes is a significant environmental challenge. Zinc oxide (ZnO) has attracted considerable attention as a non-toxic, multifunctional material for electronics, optics, piezoelectric devices, and photocatalysis, where its performance is strongly governed by morphology. In this work, we investigate the effect of hexamethylenetetramine (HMTA) on the formation and photocatalytic behavior of ZnO nanostructures synthesized from different zinc precursors, namely zinc acetate and zinc nitrate, via a one-step sol–gel process at low temperature without any post-treatment. All samples crystallize in the hexagonal wurtzite phase without detectable impurities, and the incorporation of HMTA leads to smaller, more uniform rod- and flake-like nanostructures. Although ZnO derived from zinc acetate without HMTA exhibits the highest specific surface area, ZnO synthesized in the presence of HMTA shows more favorable crystallinity, morphology, and pore connectivity, which together enhance charge separation and reactive oxygen species generation. As a result, ZnO samples synthesized with HMTA exhibit improved photocatalytic degradation of rhodamine B under UV irradiation.
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    STRUCTURAL, OPTICAL, AND VISIBLE-LIGHT DRIVEN PHOTACATALYTIC PROPERTIES OF Yb-DOPED BiVO4 NANOPARTICLES PREPARED VIA RAPID SONOCHEMICAL PROCESS
    (2023-01-01) ;
    Noinonmueng, Tanisara
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    Kansaard, Thanaphon
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    Wechprasit, Tirapat
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    This work represents the synthesis and structural, morphological, and optical characterization of rare-earth Yb-doped BiVO<inf>4</inf> materials with different Ytterbium (Yb<sup>3+</sup>) contents (0% - 5%). Yb-doped BiVO<inf>4</inf> specimens in form of fine nanoparticles were synthesized by a rapid and facile sonochemical process. The structural and morphological characterizations were observed by X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Important optical properties of the prepared samples were investigated by the diffuse reflectance technique and the corresponding optical band gaps were calculated by the mean of the Kullbelka-Munk equation. From the characterized results, it is acknowledged that incorporated Yb dopant has a significant effect on the crystalline structure of BiVO<inf>4</inf> by reducing in monoclinic phase in the pristine sample while the increasing Yb doping composition resulted in the mixed phases of monoclinic and tetragonal phases since Yb<sup>3+</sup> ions could probably induce the stabilization of the tetragonal phase in BiVO<inf>4</inf> material. Moreover, extensive doping with Yb<sup>3+</sup> exhibits considerable influence on not only structural but also optical and relevant visible - driven photocatalytic properties of BiVO<inf>4</inf> by means of the color degradation of RhB dye solution
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    Effects of Er Dopant on Structural and Optical Properties of BiVO4 Powders Prepared via Sonochemical Process
    (2022-01-01)
    Noinonmueng, Tanisara
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    Kansaard, Thanophon
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    Wechprasit, Tirapat
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    ;
    In this work, we investigate the crucial effect of Er dopant on structural, morphological and optical properties of BiVO<inf>4</inf> prepared by one-step sonochemical process. The Er doping content was varied from 0% to 10%. The structural and morphological characterization were performed by X-ray diffraction technique (XRD), Raman spectroscopy and scanning electron microscopy. XRD and Raman spectra reveal the structural transition from monoclinic to tetragonal structure induced by Er dopant. Optical properties of the prepared samples were investigated by diffuse reflectance technique and the corresponding optical band gaps were calculated indicating two optical band gaps of two major phases of the doped samples. The Er dopant has highly influence on an enhancement in photocatalytic performance under visible irradiation of BiVO<inf>4</inf> as doping content is 8%. This improved performance could be due to the size reduction and morphological change due to phase transformation induced by Er dopant accompanying mixture of optical band gaps that can assist the retardment of electron-hole pair recombination.
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    Particle Morphology and Optical Property of Silicate Powder Prepared from Waste Borosilicate Glass by High Energy Ball Milling Process
    (2022-01-01)
    Naknawa, Pakakul
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    Manivong, Aphisit
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    Chongsri, Krisana
    The aim of this work was focused on the size reduction of waste glass that was obtained from broken beaker glass in the laboratory. The particle size reduction of glass cullet was performed by a high energy ball milling process. Firstly, the obtained beaker glass was smashed into fine particles before the milling process. The milling parameters studied, which had potential effects on the efficiency of the milling process, were rotation speed, milling time and ball sizes. The particle size and morphology of before/after milled silicate powder were evaluated by a particle analyzer and a field emission scanning electron microscope (FE-SEM). It was shown that the particle size of the milled powder had decreased after milling. However, agglomeration occurred after the use of high rotation speeds and longer milling times. Furthermore, functional groups of the milled samples were analyzed by a Fourier transform-infrared (FT-IR) spectrometer. The FTIR spectra of samples of each milled condition displayede similar patterns. Meanwhile, an optical property, the scattering effect of milled samples of different particle sizes, was identified by a luminance meter. The preliminary results suggested that the minimum particle size of the milled glass was reached at 1.33 µm with milling time of 30 min at 500 rpm. Therefore, an increase of light scattering property occurred, and this correspondented to the smaller particle size of milled silicate powder.