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Nawin Viriya-empikul Pattraporn Changsuwan Kajornsak Faungnawakij 《Ceramics International》2012,38(4):2633-2636
The Sr-based fiber was prepared by electrospinning process. The effect of electric field, precursor viscosity, and calcination temperature (Tcal) was investigated at required conditions. Then the Sr-based fiber was characterized by TGA, nitrogen adsorption, SEM, TEM, and XRD to elucidate thermal transition, specific surface area, morphology, crystal structure, and crystalline phase of the samples, respectively. The result showed that the smooth fiber sample could be spun at electric field of 1.5 kV cm?1 with the suitable viscosity of ca. 5 Pa s. Finally the crystalline phase could be controlled by properly adjusting Tcal, i.e. when the Tcal was risen from 400 to 1000 °C, the crystalline phase was transformed from SrCO3 to Sr(OH)2H2O, and eventually to SrO. 相似文献
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Chuleeporn Luadthong Vorranutch Itthibenchapong Nawin Viriya-empikul Kajornsak Faungnawakij Prasert Pavasant Wiwut Tanthapanichakoon 《Materials Chemistry and Physics》2013
Nanostructured ferrite spinels AFe2O4 (A = Co, Ni, Zn) were successfully synthesized via a co-precipitation method using oxalate salt as a precursor in an anionic surfactant system in combination with a simple calcination process. High crystallinity samples of nanoparticle spinels in a grain size range of 15–100 nm were obtained by varying the calcination temperature (300–700 °C) and time (1–5 h). Their pore sizes were controlled in a range of 3 nm up to a hundred nm by tailoring the calcination conditions. Raising the calcination temperature was found to decrease the Brunauer–Emmett–Teller (BET) surface area, and broaden the pore structure due to enhanced crystal growth and agglomeration of interparticles of spinels. Transmission electron microscopy (TEM) images of ferrite spinels calcined at 300 °C showed mesoporous structures with narrow pore size distribution, and the maximum BET surface area of CoFe2O4, NiFe2O4 and ZnFe2O4 were found at 201 (Co), 315 (Ni), and 273 (Zn) m2 g−1, respectively. The magnetic hysteresis loops of the ferrite spinels at room temperature demonstrated ferromagnetism in CoFe2O4, superparamagnetism–ferromagnetism in NiFe2O4, and paramagnetism in ZnFe2O4. The highest saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc) were obtained from high crystallinity spinels calcined at 700 °C. Nanostructured AFe2O4 with high surface area and mesoporosity promises potentials as novel magnetic catalysts. 相似文献
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T. Charinpanitkul W. Suthabanditpong H. Watanabe T. Shirai K. Faungnawakij N. Viriya-empikul M. Fuji 《Journal of Industrial and Engineering Chemistry》2012,18(4):1441-1445
ZnO nanoparticles suspended in poly(acrylic acid) (PAA) were deposited onto layer-by-layer (LBL) polyelectrolyte (PET) films fabricated from poly(allylamine hydrochloride) (PAH) and PAA by dip coating method. Effect of etching time and concentration of ZnO suspension on hydrophilicity of the LBL-PET films before and after UV irradiation was examined using water contact angle measurement. 2.0 M PAH/PAA solutions with a dipping speed of 3.0 cm/min provided stable LBL-PET films with thickness sufficient for HCl etching. Glass substrates with the etched LBL-PET film dipped into 0.2 wt.% ZnO suspension exhibited the contact angle of 10° after irradiated by UV for 60 min. 相似文献
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Nawin Viriya-Empikul Noriaki Sano Takeyuki Kikuchi Sareeya Bureekaew Wiwut Tanthapanichakoon Tawatchai Charinpanitkul 《Journal of Industrial and Engineering Chemistry》2010,16(1):63-67
The titanate nanostructures with high UV absorption characteristics could be fabricated by hydrothermal method within a temperature range of 90–150 °C. TEM, XRD, BET analyses, and UV–vis spectroscopy were employed to elucidate the synthesized titanate nanostructure characteristics which were microstructure, phase transformation, specific surface area, and band gap energy, respectively. With an increase in the hydrothermal treating temperature from 90 to 120 °C, the specific surface area of titanate nanostructures was increased from 83 to 258 m2/g, while the band gap energy of titanate nanostructures was increased from 3.44 to 3.84 eV and then slightly decreased to 3.81 eV at 150 °C. The fabricated titanate nanostructures could exhibit higher UV adsorption capability but lower photocatalytic activity when compared with that of commercial TiO2 powders. 相似文献
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The solid oxide catalysts derived from the industrial waste shells of egg, golden apple snail, and meretrix venus were used as biodiesel production catalysts. Their catalytic activity in transesterification of palm olein oils and their physicochemical properties (by TG/DTA, EDX, SEM, N2 sorption, CO2-TPD, and XRD) were systematically investigated. The waste materials calcined in air with optimum conditions (temperature of 800 °C, time of 2–4 h) transformed calcium species in the shells into active CaO catalysts. The activity of the catalysts was in line with the basic amount of the strong base sites, surface area, and crystalline phase in the catalysts. All catalysts derived from egg and mollusk shells at 800 °C provided high activity (>90% fatty acid methyl ester (FAME) in 2 h). These abundant wastes showed good potential to be used as biodiesel production catalysts. 相似文献
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Kamonwat Nakason Bunyarit Panyapinyopol Vorapot Kanokkantapong Nawin Viriya-empikul Wasawat Kraithong Prasert Pavasant 《能源学会志》2018,91(5):786-796
Hydrothermal carbonization (HTC) was applied to examine the feasibility in converting coconut husk (CH) and rice husk (RH) to renewable fuel resource and valuable dissolved organic chemicals. HTC was conducted with varying process temperature (140–200 °C) and retention time (1–4 h). CH was a better feedstock to produce hydrochar as solid fuel than RH because of its compositions was significantly different. An increase in process temperature from 140 to 200 °C resulted in a decrease in hydrochar yield of CH from 77.1 to 67.8%, and corresponding decreases in O/C and H/C from 0.6 and 1.4 to 0.4 and 1.2, respectively, and this was associated to dehydration and decarboxylation reactions. Fuel ratio and HHV were in the range of 0.66–0.86 and 20.7–23.9 MJ/kg, respectively. Liquid fractions (LF) from both RH and CH were found to be abundant in dissolved organic chemicals which were regarded as valuable intermediate chemicals, including furfural, furfuryl alcohol, hydroxymethylfurfural (HMF), and low molecular-weight carboxylic acids (lactic acid, formic acid, acetic acid, levulinic acid, and propionic acid). 相似文献
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T. Charinpanitkul P. Lorturn N. Viriya-empikul J. Wilcox 《Materials Research Bulletin》2011,46(10):1604-1609
With the hydrothermal treatment, titanate nanostructure with distinctively different morphology and surface characteristics was successfully synthesized from commercial rutile titania powder dispersed in accommodating media which were deionized water or NaOH solution. Hybridized materials of titanate nanoparticles and carbon nanotubes (CNT) were also synthesized by the hydrothermal treatment process. Intrinsic interaction of titanate nanoparticles and CNTs could be confirmed by spectroscopic analysis. The synthesized titanate nanoparticle/CNT hybridized material was then employed for fabricating a working electrode of dye-sensitized solar cells (DSSC). Based on experimental results, DSSC fabricated from the hybridized titanate nanoparticles and carbon nanotubes could provide the highest photoconversion efficiency of approximately 3.92%. 相似文献
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Kajornsak Faungnawakij Nawin Viriya-empikulWiwut Tanthapanichakoon 《International Journal of Hydrogen Energy》2011,36(10):5865-5874
In the present study, a thermodynamic analysis of the autothermal reforming of dimethyl ether (DME) for the production of hydrogen was carried out. The results clearly indicated that the carbon formation behavior, the boundary conditions between coke-free and coking regions, and the equilibrium composition of the reformate were dependent on the steam/DME ratio, O2/DME ratio, temperature, and pressure of the system. For instance, carbon formation was effectively suppressed as the steam/DME ratio increased from 0 to 5, the O2/DME ratio increased from 0 to 3, or the temperature rose from 100 to 1000 °C. In contrast, carbon formation was enhanced as the pressure was increased from 0.5 to 10 atm. The boundary temperature of coke-free operation decreased with an increase in the steam/DME and O2/DME ratios. More specifically, at a steam/DME ratio of 3-5 and an O2/DME ratio of 0-3, the boundary temperature ranged from 50 to 280 °C (when CH4 formation was promoted) and 380 to 670 °C (when CH4 formation was suppressed), respectively. Furthermore, at elevated temperatures, H2 and CO formations were enhanced, and CH4 formation was inhibited. The addition of steam enhanced H2 production while reducing CO formation. On the contrary, an increase in the O2/DME ratio reduced H2 production while enhancing CO formation. Interestingly, the desired temperature for thermo-neutral condition, in which energy consumption was zero, can be achieved by correctly controlling the O2/DME and steam/DME ratios. 相似文献
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Kamonwat Nakason Bunyarit Panyapinyopol Vorapot Kanokkantapong Nawin Viriya-empikul Wasawat Kraithong Prasert Pavasant 《能源学会志》2018,91(2):184-193
Hydrothermal carbonization (HTC) of cassava rhizome (CR) was performed to investigate the effect of process parameters including temperature, time, and biomass to water ratio (BTW) on characteristics of hydrochar and liquid fraction products. The effect of temperature was two-fold. First, an increase in reaction temperature from 160 to 180 °C decreased hydrochar yield from 54 to 51%, however, a further increase of temperature from 180 to 200 °C saw an increase in the hydrochar yield to 58%. This was associated to degradation, polymerization, and condensation reactions during HTC. The hydrogen/carbon and oxygen/carbon atomic ratios decreased from 1.4 and 0.6 at 160 °C to 1.2 and 0.4 at 200 °C, respectively. The liquid fraction contained various valuable chemical species including, glucose, furan compounds, (furfural, furfuryl alcohol, hydroxymethylfurfural), volatile fatty acid (succinic acid, lactic acid, formic acid, acetic acid, levulinic acid, and propionic acid) with their highest yields (wt.% dry raw material) of 4.5, 18.5, and 24.3, respectively. 相似文献
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