KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 14

Some of the metrics are blocked by your
consent settings
Synergy of functionalized activated carbon and ZnO nanoparticles for enhancing photocatalytic degradation of methylene blue and carbaryl
(2024-10-01)
Rungsawang, Tipawan
;
Krobthong, Sucheewan
;
Paengpan, Krisanachai
;
Kaewtrakulchai, Napat
;
Manatura, Kanit
This study proposes preparing ZnO and ZnO/activated carbon (AC) for photocatalytic applications. ZnO and AC were synthesized using precipitation and carbonization processes, respectively. Particle sizes of ZnO and ZnO/AC were estimated at 121–135 nm. The crystalline structure analysis confirmed the presence of hexagonal wurtzite structures in ZnO. Microcrystalline graphite and amorphous carbon structures were observed in AC. The combination of these characteristics was observed in ZnO/AC. ZnO/AC exhibited an increase in surface area from 25.36 to 29.86 m2/g and a decrease in pore diameter from 5.66 to 4.31 nm. The chemical states of ZnO and AC remained unchanged. Therefore, the nanocompound structure of ZnO/AC can be inferred. The ZnO/AC nanocompounds were then employed to degrade methylene blue (MB) dye and carbaryl (CBR) insecticide, demonstrating excellent photocatalytic performance compared to pure ZnO. The apparent degradation rate constant reached an average value of 3.49 × 10−3 and 16.25 × 10−3 min−1 for MB and CBR, respectively. AC functions as carrier collectors in the ZnO/AC nanocompound structures due to the suitable energy band level for facilitating electron and hole transfers. This results in recombination suppression and prolonged lifetime, thus enhancing photocatalytic activity. The finding suggests the potential use of ZnO/AC nanocompounds to degrade agricultural chemicals in contaminated natural water under sunlight.
Some of the metrics are blocked by your
consent settings
A novel photocatalyst of Y2O3-BaO-ZnO ternary system for enhanced photocatalytic degradation of carbofuran insecticide
(2024-08-01)
Sujinnapram, Supphadate
;
Krobthong, Sucheewan
;
Moungsrijun, Sasimonton
;
Boonruang, Chatdanai
;
Kaewtrakulchai, Napat
A novel Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system was synthesized via precipitation of a mixture of Y(NO<inf>3</inf>)<inf>3</inf>.6 H<inf>2</inf>O:Ba(NO<inf>3</inf>)<inf>2</inf>:Zn(NO<inf>3</inf>)<inf>2</inf>.6 H<inf>2</inf>O using some Fibonacci sequences. The Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO was applied to the photocatalyst to investigate the degradation of carbofuran insecticide. The Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO prepared at the sequence ratio of 5:8:13 (YBZ5) exhibited the highest photocatalytic performance. Morphological characterization showed that the particle size of the YBZ5 sample was significantly smaller than that of ZnO by over half, possibly providing high surface areas. The crystalline structure, functional group, and surface chemical composition investigations confirmed the presence of Y<inf>2</inf>O<inf>3</inf>, BaO, and ZnO. The fluorescence study exhibited no difference. Based on band gap energy and energy band alignment analysis, the Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system demonstrated a well-aligned valence band. The energy band alignment analysis revealed a good alignment of the valence band for continuous hole transport in the Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system. The alignment induces charge separation which reduces recombination and provides efficient active carriers at the surfaces of the photocatalyst, allowing reactions with toxic molecules. Therefore, the synergistic function of high surface areas and appropriate energy band alignments of the novel Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system is considered the crucial factor in the enhancement of photocatalytic performance.
Some of the metrics are blocked by your
consent settings
Magnetically separable CeO2/CoFe2O4 heterojunction photocatalysts for dye degradation: characterization and mechanism
(2024-01-01)
Seeharaj, Panpailin
;
Pasupong, Patchara
;
Choojun, Kittisak
This study developed magnetically separable CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> heterojunction photocatalysts for dye degradation to reduce water pollution. The CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> nanocomposites with different CeO<inf>2</inf> ratios (10, 20, and 30 wt%) were prepared by a precipitation method. The nanocrystalline 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst with a surface area of 117 m2.g−1, E<inf>g</inf> 2.37 eV, and uniform distribution of quasi-spherical CeO<inf>2</inf> minor phase (cubic fluorite structure with particle size 3 ± 1 nm) throughout the distorted spherical CoFe<inf>2</inf>O<inf>4</inf> major phase (cubic spinel structure with particle size 9 ± 3 nm) showed the best photocatalytic performance for methylene blue (MB) degradation under UV light irradiation at the efficiency of 88.7% and the apparent rate constant (k) of 0.0138 min−1. The 20%CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> photocatalyst had a good magnetic response and could be easily separated from the dye solution by applying an external magnetic field. The reusability test showed lower photodegradation efficiency due to the adsorption of residual MB dye on the photocatalyst surface. The formation of heterojunction at the interfaces of CeO<inf>2</inf>/CoFe<inf>2</inf>O<inf>4</inf> facilitated the photogenerated charge separation and increased availability of active species of holes (h+) and hydroxy radicals (∙OH), which were the key factors in improving the photocatalytic activity.
Some of the metrics are blocked by your
consent settings
STRUCTURAL, OPTICAL, AND VISIBLE-LIGHT DRIVEN PHOTACATALYTIC PROPERTIES OF Yb-DOPED BiVO4 NANOPARTICLES PREPARED VIA RAPID SONOCHEMICAL PROCESS
(2023-01-01)
Boonyarattanakalin, Kanokthip
;
Noinonmueng, Tanisara
;
Kansaard, Thanaphon
;
Wechprasit, Tirapat
;
Mekprasart, Wanichaya
This work represents the synthesis and structural, morphological, and optical characterization of rare-earth Yb-doped BiVO<inf>4</inf> materials with different Ytterbium (Yb3+) 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 Yb3+ ions could probably induce the stabilization of the tetragonal phase in BiVO<inf>4</inf> material. Moreover, extensive doping with Yb3+ 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
Some of the metrics are blocked by your
consent settings
Photocatalytic CO2 reduction with new band gap energy evaluation from spectroscopic relationship of graphene-Mg2CuSnCoO6 composite bridged with organics
(2021-10-01)
Oh, Won Chun
;
Areerob, Yonrapach
A new structure of graphene-Mg<inf>2</inf>CuSnCoO<inf>6</inf> composite bridged with gallic acid (GMG) was synthesized with a novel method. Band gap energy of the newly synthesized nanocomposite was evaluated with a laser-wavelength region and DRS method. Evaluation and analysis were based on the relationship among XRD, HRTEM, XPS, Raman scattering, and computer simulated model structure. Changes in the structure of graphene or graphene-based composite were associated with location changes of the valence band and the conduction band. Electron density was used to confirm the number of electrons by computer simulation. Finally, such graphene-Mg<inf>2</inf>CuSnCoO<inf>6</inf>-gallic acid nanocomposite was used for photocatalytic CO<inf>2</inf> reduction into methanol. Under UV-light irradiation, the highest methanol yield was 5.576% with 0.6 g of scavenger. This work might offer a promising strategy for measuring band gap energies of different types of semiconductors.
Some of the metrics are blocked by your
consent settings
Characterization, X-ray absorption spectroscopic analysis and photocatalytic activity of Co/Zn co-doped TiO2 nanoparticles synthesized by one-step sonochemical process
(2021-10-01)
Mekprasart, Wanichaya
;
Pavasupree, Sorapong
;
Jayasankar, C. K.
;
Ravuri, Balaji Rao
;
Wattanawikkam, Chakkaphan
A novel one-step preparation of sonochemical method was applied to synthesize Co/Zn co-doped TiO<inf>2</inf> nanoparticles using a sonicator of 750 W, 20 kHz for 30 min at room temperature. The formation of the anatase TiO<inf>2</inf> phase for all as-prepared samples was observed from XRD results with a crystalline size in nanoscale. The use of ultrasound allowed for the successful doping of both Co and Zn into the TiO<inf>2</inf> lattice, which was confirmed by Synchrotron light including X-ray near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy. Ti K-edge, Co K-edge, and Zn K-edge XANES spectra exhibited the dominating +4, +2, and +2 valence state of Ti, Co, and Zn in as-prepared samples, respectively. A detailed XANES and EXAFS data analysis give strong evidence that the Co/Zn dopants partially replace the Ti atom of the TiO<inf>2</inf> host. The Co/Zn co-doping extends the light absorption of the host to the visible region and restricts the e+/h+ recombination. The photocatalytic activity of samples was tested for degradation of Rhodamine B dye solution under visible light irradiation. The as-synthesized of the co-doped catalyst was presented as highly efficient, with 2.5 and 5 times dye degradation compared with single-doped and bare TiO<inf>2</inf>.
Some of the metrics are blocked by your
consent settings
Effect of Ultrasonic Irradiation Time on Physical Properties and Photocatalytic Performance of BiVO4 Nanoparticles Prepared via Sonochemical Process
(2021-01-01)
Kansaard, Thanaphon
;
Bangbai, Chatpong
;
Jayasankar, C. K.
;
Pecharapa, Wisanu
Currently, photocatalyst materials have gained considerable attraction because of very rich economic performance of decomposition of highly toxic organic compound to lower toxic composition. The effort of this work was paid to study the effect of sonochemical ultrasonic irradiation time on the relevant properties of visible-light-driven bismuth vanadate (BiVO<inf>4</inf>) photocatalyst without any further thermal treatment process. The chemical bonding of BiVO<inf>4</inf> nanopowder was investigated by Fourier transform infrared (FTIR) and Raman spectrometer technique. Meanwhile their structure was characterized by X-ray diffraction technique (XRD). Field emission scanning electron microscope (FE-SEM) was used to observe particle morphology and chemical compositions was investigated by Energy-dispersive X-ray spectroscopy (EDX). Photocatalytic performance of BiVO<inf>4</inf> nanopowder was studied by decomposition of organic dye as organic pollutant model using visible light to excite photocatalyst materials. It was found that sonochemical irradiation time supplied during chemical process can effectively expedite the formation of BiVO<inf>4</inf> nanoparticle. The optimized condition to obtain the product with enhanced photocatalytic performance of 60% decomposition is achieved as the sample was prepared at 40 min ultrasonic irradiation.
Some of the metrics are blocked by your
consent settings
Structural studies and photocatalytic properties of Mn and Zn co-doping on TiO2 prepared by single step sonochemical method
(2020-06-01)
Wattanawikkam, Chakkaphan
;
Pecharapa, Wisanu
Titanium dioxide nanoparticles dual doped with zinc and manganese were prepared by the single step of sonochemical method using the sonicator with 20 kHz and 750 W for 30 min. Phase structure analysis results showed that the pure anatase phase was detected for all prepared samples. TEM analysis reveals the nanosized structure with uniformity of nanoparticles. The calculated bandgap energies change to be below the typical band gap energy of bare TiO<inf>2</inf> and single doped sample suggesting high ability to harvest visible light. X-ray absorption spectroscopy was conducted to investigate the electronics structure and to study the local structure of prepared samples. XANES results confirmed the existence of Ti4+ ions in all prepared samples with anatase crystal structure. EXAFS analysis indicates the Ti4+ site was substituted by Mn and Zn dopant ions. The photocatalytic performance was evaluated by degradation of Rhodamine B dye solution under visible light irradiation. The results revealed that the dually Mn–Zn doped TiO<inf>2</inf> sample exhibited excellent photocatalytic activity comparing to single doped and pure TiO<inf>2</inf>. The complete degradation of dye was achieved at optimum condition of 1 mol%-Zn and 2 mol%-Mn molar ratio. The highest photodegradation rate constant was found to be 0.0238 min−1, which is 10 times greater than pure-TiO<inf>2</inf> samples.
Some of the metrics are blocked by your
consent settings
Ultrasonically-assisted surface modified TiO2/rGO/CeO2 heterojunction photocatalysts for conversion of CO2 to methanol and ethanol
(2019-11-01)
Seeharaj, Panpailin
;
Kongmun, Panyata
;
Paiplod, Piyalak
;
Prakobmit, Saowanee
;
Sriwong, Chaval
Converting CO<inf>2</inf> to usable fuel may contribute to lowering of global warming, thus this study developed effective heterojunction photocatalysts for the photoreduction of CO<inf>2</inf> with water into methanol and ethanol fuels. The photocatalysts were prepared from combining surface modified titanium dioxide (TiO<inf>2</inf>) nanoparticles with reduced graphene oxide (rGO) and cerium oxide (CeO<inf>2</inf>). The TiO<inf>2</inf> surfaces were firstly modified via the sono-assisted exfoliation, with high intensity ultrasonic waves (ultrasonic horn, 20 kHz, 150 W/cm2) in 10 M NaOH for 1 h. Highly reactive nanosheets delaminated from outer surfaces of the primary TiO<inf>2</inf> crystals leading to an increase in specific surface active area, light absorption and decrease in electron-hole recombination rate, which enhanced photocatalytic activity. Then, 0.75 wt% rGO and 1 wt% CeO<inf>2</inf> were incorporated into the surface modified TiO<inf>2</inf> to promote photogenerated charge separation, electron mobility and CO<inf>2</inf> absorptivity. The modified TiO<inf>2</inf>/rGO/CeO<inf>2</inf> photocatalysts exhibited superior photocatalytic performance by producing methanol at 641 μmol/g<inf>cat</inf>h and ethanol at 271 μmol/g<inf>cat</inf>h, almost 7 times higher than rates from pure TiO<inf>2</inf>. The significant improvement in CO<inf>2</inf> photoconversion activity was mainly attributed to the high interfacial contact area and strong connection between the reactive delaminated TiO<inf>2</inf> nanosheets, rGO and CeO<inf>2</inf>, which, in turn, facilitated the flow of large number of photogenerated charge carriers to react with the absorbed species, and the multi-step charge transportation due to the heterojunction effect that effectively retarded electron-hole recombination.
Some of the metrics are blocked by your
consent settings
Comparison study of photocatalytic activity of titanium-rich materials derived from natural minerals ores using acidic leaching
(2017-01-01)
Kansaard, Thanaphon
;
Phoohinkong, Weerachon
;
Mekprasart, Wanichaya
;
Sanguanpak, Samanya
;
Wannakon, Anucha
Over past decades, titanium dioxide-based materials have been recognized as effectively practical photocatalysts for purification of toxicity waste. However, pure TiO<inf>2</inf> photocatalyst is highly active under ultraviolet illumination. In this work, the effort has been focused on the synthesis of titanium-rich materials starting from minerals ores ilmenite ores and leucoxene ores by ball-milling process in combined with hydrochloric acid leaching method with optimized conditions. Crystallinity and morphologies of as-prepared samples were characterized by X-rays diffraction technique and scanning electron microscope. The photocatalytic activities of both derived-materials were studied and compared by degradation of Rhodamine B organic dye as organic toxicity compound under ultraviolet light and visible light. The results illustrate that the leucoxene-derived sample exhibits superior catalytic performance to the sample derived from ilmenite ores due to the greater Ti-content of the starting leucoxene ores.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results