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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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    Curcumin-sensitized TiO2for enhanced photodegradation of dyes under visible light
    (2014-01-01)
    Buddee, Supat
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    Wongnawa, Sumpun
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    Sriprang, Pimpaporn
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    Curcumin was coated on P25 TiO<inf>2</inf> by using impregnation method from freshly prepared curcumin solution. The resulting products (Cur-TiO <inf>2</inf>-P25) was studied by several techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectroscopy, specific surface area by the Brunauer-Emmett-Teller method, and UV-Vis diffused reflectance spectroscopy. Experimental results revealed that impregnation of curcumin at 0.5, 3, 5, and 7 wt% did not affect the native phase of anatase and rutile in P25 significantly, however, it caused red shift of absorption onset in all curcumin-coated samples. The Cur-TiO<inf>2</inf>-P25 showed enhanced adsorption efficiency and increased photocatalytic activity under visible light with optimal result at 5 wt% curcumin content. Commercial anatase and rutile coated with curcumin (Cur-TiO<inf>2</inf>-an and Cur-TiO<inf>2</inf>-ru) were also prepared by the same method for the use in comparative studies of photodegradation of dyes. Cur-TiO<inf>2</inf>-an and Cur-TiO<inf>2</inf>-ru were also characterized with some selected equipment above but not as extensively as the Cur-TiO <inf>2</inf>-P25. Curcumin coating helped improve photocatalytic efficiencies of P25 and anatase but not for rutile. The mechanism of photocatalytic reaction was proposed that under visible light irradiation, curcumin molecule could act as dye sensitizing agent that injected electron into the conduction band of TiO<inf>2</inf> leading to photodegradation of dyes. © Springer Science+Business Media 2014.
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    High photocatalytic performance of 3D porous-structured TiO2@natural rubber hybrid sheet on the removal of indigo carmine dye in water
    (2019-08-01) ; ;
    Sriwong, Sukanpirom
    Due to the high efficiency of photocatalytic process for the environmental treatments, titanium dioxide (TiO<inf>2</inf>) is a popular used as photocatalyst material. However, the practical uses of TiO<inf>2</inf> in powder form have some drawbacks as well as the difficult reusability. In this work, 3D porous-structured TiO<inf>2</inf>@natural rubber (TNR) hybrid sheets with high photocatalytic performance were presented. TNR hybrid sheets prepared by a facile and low-cost method, which is based on the mixing of natural rubber (NR) latex (60% high ammonia) and ammoniacal TiO<inf>2</inf> (P25) suspension, followed by vacuum filtration through a sintered glass template to make a 3D porous network structure on the surface of the sheets. The obtained TNR sheet samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), X-ray diffractometer (XRD) and reflection Fourier transformed infrared spectroscopy (FT-IR) techniques. The results showed that the surface morphologies of TNR hybrid sheets appeared as porous-structured which had high roughness and with various tiny pores on the surface. The photocatalytic properties of the prepared TNR hybrid sheets were tested using indigo carmine (IC) dye under UV light irradiation. It was found that the highest photodegradation efficiency was achieved with the TNR_5 wt% hybrid sheet sample. Compared with the sheets reported in previous works, the TNR sheet shows higher efficiencies than those sheets due to its higher amount of TiO<inf>2</inf> particles at the surface, more porous structure with high rough surface, and abundance of tiny pores on the TNR sheet surface. Moreover, the recyclability and stability of TNR sheet indicated that upon using 10 cycles (remains 98% efficiency), in which the stability of the sheet surface well-confirmed by SEM and XRD techniques, as well. From above the study, this 3D porous-structured TNR hybrid sheet could be a new alternative strategy for the water or wastewater treatment in industry concerning with the easy use, recovery, reusability and stability of the photocatalysts.
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    Synthesis of reduced graphene oxide quantum dots from graphene oxide via hydrothermal process and theirs structural, luminescence and magnetic properties
    (2023-01-01)
    Buatong, Nattha
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    Background: Reduced graphene oxide quantum dots (rGO-QDs) have attracted much interest because of its exceptional chemical and physical properties and novel applications in a new technology and devices such as, energy storage, electrochemical, photocatalysis, sensing, drug delivery, bioimaging and anticancer therapy. Methods: In this work, we reported a correlation study of the structural, morphological, luminescence and magnetic behavior of rGO-QDs as a function of hydrothermal reduction temperatures (such as 90 °C, 120 °C, 150 °C and 180 °C) of GO sheets precursor via hydrothermal process. GO precursor and the obtained rGO-QDs samples were confirmed and analyzed by several techniques such as, XRD, Raman, XPS, TEM, PL, UV–Visible, Fluorescence and EPR. Significant findings: Influence of hydrothermal cutting process with different temperatures (90 °C, 120 °C, 150 °C and 180 °C) on the evolution of structural, morphologies, luminescence and magnetic behavior for the changes of large GO sheets into ultra-small rGO-QDs is presented. XRD result confirmed the effect of increasing temperature on the hydrothermal cutting process which led to a decrease in D-spacing values of rGO-QDs products. While Raman results indicates the trend of I<inf>D</inf>/I<inf>G</inf> ratio decreases along with increasing hydrothermal reduction temperatures. XRS analysis revealed that the percentage of carbon content of GO precursor (∼64%) was shifted value to ∼83% for obtained rGO-QDs sample prepared at 180 °C. TEM images shown that a very thin plate-like shape with ultrasmall average diameter of rGO-QDs samples in rage of 22±2 nm to 8 ± 2 nm. The optical and PL results well-confirmed the characteristic quantum size effect of all rGO-QDs samples. Finally, the EPR signals indicate the crossover between paramagnetic and diamagnetic are depended on the reduction temperature. The rGO-QDs prepared at 180 °C do not give any EPR signal, signify the nonmagnetic nature. This indicate that the basal plane of rGO-QDs at 180 °C has nearly perfect sp<sup>2</sup> network of graphene.
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    Preparation, characterization, and supercapasitive properties of CoO-NiO microflowers incorporated with graphene oxide and reduced graphene oxide hybrid materials
    (2018-01-01)
    Saei, Worawee
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    This research investigated the preparation, characterization and supercapacitive properties of cobalt oxide-nickel oxide (CoO-NiO) microflowers incorporated with graphene oxide (GO) and reduced graphene oxide (RGO) nanosheets. These hybrid materials were easily prepared through a direct mixing of CoO-NiO powder suspended in acidic solution with the appropriate amount of GO and RGO loading to make CoO-NiO/GO and CoO-NiO/RGO hybrid samples, respectively. Then, the obtained hybrid samples were characterized by X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The results demonstrated that the crystalline phases and functional groups of all hybrid samples are corresponding to pristine CoO-NiO and RGO. SEM results showed that the CoO-NiO microflowers were impregnated and well-combined with both GO and rGO nanosheets. Moreover, the supercapacitive behavior of pristine CoO-NiO and all hybrid samples were studied using cyclic voltammetry (CV) technique. The results revealed that all hybrid samples exhibited much higher the current density than those of the bare CoO-NiO. Thus, this research indicates that the supercapacitive properties of CoO-NiO incorporated with both GO and RGO hybrid materials are superior to the pure CoO-NiO microflowers.
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    Effect of rGO nanosheet loading in SiO2/rGO hybrid nanocomposites for enhancing optoelectrical, physical, and electrochemical properties
    (2025-05-01)
    Khammahong, Sunisar
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    In this study, silicon dioxide nanoparticles (SiO<inf>2</inf>NPs) mixed with reduced graphene oxide nanosheets (rGONS) and hybrid nanocomposites (S/rGOHNCs) were synthesized to study the opto-electrical, physical and electrochemical properties. S/rGOx%HNCs samples with rGONS at various loadings (10, 30, 50, and 70 wt%) were prepared SiO<inf>2</inf>NPs and rGONS suspensions in ultrasonication process by conventional heating. The SiO<inf>2</inf>NPs, rGONS and S/rGOx%HNCs were characterized and properties confirmed by XRD, Raman spectroscopy, FT-IR spectra, UV–Vis, SEM, EDX and TGA techniques. The electrical conductivity carrier concentration, energy gap, and dielectric constant increased with rGONS loading. The S/rGO30HNCs exhibited the highest thermal conductivity, 0.7 W/m·K, and Vickers microhardness, 41.0 HV. The value of electrochemical capacity of S/rGO70HNCs, 66.95 F/g, was due to the appropriate ratio of rGONS and SiO<inf>2</inf>NPs which significantly contributed to increasing redox reaction. The findings offered SiO<inf>2</inf>NPs mixed rGONS hybrid nanocomposites with enhanced optoelectrical (electrical, optical, dielectric), physical (mechanical, thermal) and electrochemical properties.
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    Removal of methylene blue dye using metal-free g-C3N4 photocatalyst over natural sunlight irradiation
    This work presented the high activity of metal-free g-C<inf>3</inf>N<inf>4</inf> photocatalyst for methylene blue (MB) removing over natural sunlight irradiation. These g-C<inf>3</inf>N<inf>4</inf> photocatalysts materials were synthesized by a conventional thermal condensation method using melamine as a precursor under treated at the various annealing temperatures (450 °C, 500 °C, 550 °C, 600 °C and 650 °C). All assynthesized samples were characterized and confirmed by a several techniques, such as, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectrometer (DRS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) specific surface area. XRD and FTIR results confirmed that the as-synthesized g-C<inf>3</inf>N<inf>4</inf> samples were completely synthesized at annealing temperature of 500 °C. SEM images showed the morphologies of the g-C<inf>3</inf>N<inf>4</inf> samples had more flake-like structures upon the increasing of annealing temperatures. WhileDRS results indicated that the absorption edges of as-synthesized g-C<inf>3</inf>N<inf>4</inf> samples were shifted to visible-light region, except the sample as-synthesized at 650 °C (g-C<inf>3</inf>N<inf>4</inf>-650 °C). Moreover, the photocatalytic properties of metalfree g-C<inf>3</inf>N<inf>4</inf> photocatalyst materials were evaluated by degrading of MB dye solution under natural sunlight irradiation for 100 min. The results revealed that the highest photocatalytic activity was exhibited by the sample synthesized at 600 °C, which the apparent rate constant (kapp.) was 0.0291min<sup>-1</sup>. The orders of activities as:g-C<inf>3</inf>N<inf>4</inf>-600°C > g-C<inf>3</inf>N<inf>4</inf>-650 °C > g-C<inf>3</inf>N<inf>4</inf>-550 °C > g-C<inf>3</inf>N<inf>4</inf>-500°C > g-C<inf>3</inf>N<inf>4</inf>-450°C. Hence, the metal-free g-C<inf>3</inf>N<inf>4</inf> photocatalyst appears to be an attractivematerial for water or wastewater purification applications over activated by sunlight irradiation.
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    Synthesis and electrochemical properties of activated lignite carbons-reduced graphene oxide nanocomposites symmetric supercapacitors
    (2024-08-15)
    Tuichai, Wattana
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    Karaphun, Attaphol
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    Chanlek, Narong
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    Swatsitang, Ekaphan
    Ultra-fast chargeable or rechargeable symmetric carbon-based supercapacitors (SCSs) with high capacity, inexpensive, and non-flammability have attracted much attention for electronics and energy storage devices. However, improving both high redox reaction and ion transport/diffusion processes by enhancing high energy storage performance and rapid ion/electron transport SCSs electrode materials remains challenging. Herein, we presented a successful preparation of activated lignite carbons-reduced graphene oxide (ALC-rGO) nanocomposite (NCp) with the ALC:rGO ratio of 80:20 wt% by a one-pot hydrothermal for high electrochemical performance. Importantly, the matrix of ALC-rGO NCp was primary amorphous carbon with hexagonal graphitic layers and pore structures of plentiful micropores and mesopores. Remarkably, the ALC-rGO NCp electrode exhibited a maximum specific capacitance (C<inf>sc</inf>) of 152.12 F/g at 0.5 A/g. Interestingly, the SCSs-ACL-rGO device could illustrate a good performance at a potential voltage of 1.8 V with C<inf>sc</inf> of 50.90 F/g at 1 A/g and capacity retention of 96.0 % at 5 A/g after 2,000 cycles GCD test.
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    A flow-circulation system incorporating a PVP-BiOBr@rGO assembly for simultaneous degradation and detection of oxytetracycline in fish farm wastewater
    (2025-05-27) ;
    Suknakhin, Nichakarn
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    Sonsaket, Thanamat
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    Teerasong, Wanatchaporn
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    This work focuses on developing a new flow-circulation system for simultaneous detection and degradation of oxytetracycline (OTC) in fish farm wastewater to address a need for antibiotic abatement in wastewater treatment. Polyvinyl pyrrolidone capped bismuth oxybromide assembled with a reduced graphene oxide (PVP-BiOBr@rGO) photocatalyst was solvothermally synthesized and characterized. The prepared photocatalyst exhibited a morphological flower-like structure with a high surface area, 47.59 m<sup>2</sup> g<sup>−1</sup>. Its band gap energy was 2.93 eV. A ternary PVP-BiOBr@rGO composite showed lower charge recombination than its pure form. PVP-BiOBr@rGO was filled inside a catalyst column of a flow system, with a spectrophotometer at the column end. Wastewater was continuously transported through the column and OTC spectrophotometrically examined during its degradation. The wastewater was recirculated until the OTC concentration was minimized. This system achieved 90.3% degradation of OTC within 180 min. The catalyst column could be regenerated for 2 cycles. The proposed flow system offers the advantages of ease of use, inline operation, and real-time sensing. This highlights a potential for real-world sustainable wastewater treatment applications.
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    Immobilization of Silver Doped Titanium Dioxide onto Stainless Steel Wire Mesh for Photocatalytic Degradation of Gaseous Formaldehyde under Visible Light Irradiation
    (2022-03-01) ;
    Klypoo, Akekarat
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    Khingram, Aiyakub
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    Natluecha, Ratima
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    Titanium dioxide (TiO<inf>2</inf>) photocatalysis can degrade air pollutants into nontoxic substances but it can only be excited by UV light. To eliminate this limitation, silver (Ag) and/or graphene oxide (GO) doped TiO<inf>2</inf> are applied to enhance visible light photocatalytic activity. In this study, Ag-TiO<inf>2</inf> (0. 5%, 1%, 2% w/w), GO/TiO<inf>2</inf> and GO/Ag-TiO<inf>2</inf> were synthesized and then coated on stainless steel mesh. Crystalline and molecule structures, chemical compositions and optical properties of the prepared photocatalyst samples were characterized with X-ray diffraction spectroscopy, X-ray fluorescence spectroscopy, Raman spectroscopy, UV-visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, and Scanning electron microscopy equipped with Energy dispersive X-ray spectroscopy techniques. The photocatalytic performances of the various doped catalysts were evaluated according to their abilities to degrade gaseous formaldehyde (HCHO) under visible light. The effect of operational parameters on the photocatalytic degradation of HCHO including layer numbers of photocatalyst, powers of fluorescent lamp and flow rates of HCHO were observed. The results indicated that the presence of Ti, O and Ag elements in Ag-TiO<inf>2</inf> and Ti, O, Ag and C elements in GO/Ag-TiO<inf>2</inf> was confirmed. Proper dispersion of the photocatalyst on the wire mesh was exhibited. Under visible light, the incorporation of Ag and GO in TiO<inf>2</inf> photocatalysts produced higher degradation rates of HCHO than pure TiO<inf>2</inf>. The optimum operating conditions of HCHO degradation at initial concentration of 108.7±1.15 ppm over visible light irradiation for 30 min were 5 layers of 0.5% Ag-TiO<inf>2</inf>, 72 W fluorescent light and 300 ml/ min of HCHO flow rate. Under these conditions, the removal efficiency of gaseous HCHO was 76.70±0.73%.