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1.
2.
Optimization of reduction potential for electroseparation was studied for the recovery of gold, copper, and lead from acidic
solution. A linear sweep voltammetric method enabled us to determine characteristic reduction potentials for each metal and
the kinetics of the metal deposition indicated by current-voltage curves. In order to precipitate the metal species sequentially,
reduction potentials were examined for the individual and mixed solutions of Au(III), Cu(II), and Pb(II). The three metals
were reasonably well isolated from the mixed solutions such as Cu(II)/ Pb(II) and Au(III)/Cu(II)/Pb(II) in the order of the
corresponding reduction potentials, in particular, the mass transfer controlled reduction potentials, obtained from linear
sweep voltammetry (LSV) measurement. 相似文献
3.
Hydrophobicity and catalytic properties of Ti-MFI zeolites synthesized by microwave and conventional heating 总被引:1,自引:0,他引:1
Cheng-Hua Xu Taihuan Jin Sung Hwa Jhung Jong-San Chang Jin-Soo Hwang Sang-Eon Park 《Catalysis Today》2006,111(3-4):366-372
Ti-incorporated MFI zeolite (Ti-MFI-MW) has been synthesized with microwave heating. Their physicochemical properties such as surface hydrophobicity, and adsorption and catalytic properties have been compared with those of Ti-incorporated MFI zeolite (Ti-MFI-CH) prepared by conventional hydrothermal method. Competitive adsorption measurements with toluene and water revealed that the hydrophobicity index of Ti-MFI-MW (8.0) is higher than that of Ti-MFI-CH (6.2). IR spectra showed that Ti-MFI-MW also has a lower content of surface hydroxyl groups and adsorbs a larger amount of 1-hexene than Ti-MFI-CH. These results pointed out that Ti-MFI-MW is more hydrophobic than Ti-MFI-CH. Epoxidation reactions of 1-hexene and styrene with hydrogen peroxide have been conducted to investigate catalytic properties of the Ti-MFI zeolites according to the synthesis method. The conversions and epoxide selectivities over Ti-MFI-MW are higher than those over Ti-MFI-CH due to the enhanced surface hydrophobicity. 相似文献
4.
The experimental measurements of the basic four physical properties (solubility, vapor pressure, density and viscosity) of the lithium bromide + 1,3-propanediol + water system (LiBr/HO(CH2)3OH mass ratio = 3.5), a possible new working fluid for absorption heat pump, were carried out. Solubility was measured by the visual polythermal method in the temperature range from 264.65 to 358-95 K, and vapor pressure by the boiling point method from 330.75 to 408.45 K. Densities and viscosities were also measured by using a set of hydrometers and Ubbelohde-type capillary viscometers in the temperature range from 283.15 to 343.15 K. Each measured data set was correlated with a proper equation, and all the correlation results showed good agreement between measured and calculated values. Using the correlation results the Dühring chart was constructed and thus the system was found to be able to have a high absorber temperature, which is essential for the design of air-cooled absorption chiller. 相似文献
5.
Selective crystallization of CoAPO-34 and VAPO-5 molecular sieves under microwave irradiation in an alkaline or neutral condition 总被引:1,自引:0,他引:1
Sung Hwa Jhung Jin-Ho Lee Ji Woong Yoon Jin-Soo Hwang Sang-Eon Park Jong-San Chang 《Microporous and mesoporous materials》2005,80(1-3):147-152
Syntheses of cobalt- and vanadium-incorporated aluminophosphate molecular sieves (CoAPO and VAPO) with AFI and CHA structures have been studied using an alkaline or neutral gel under microwave irradiation and conventional hydrothermal heating. Microwave synthesis gives rise to the selective crystallization of CoAPO-34 with a CHA structure and VAPO-5 with an AFI structure, while the conventional hydrothermal crystallization brings CoAPO-5 and VAPO-34 through the gradual transformation of CoAPO-34 and VAPO-5, respectively, as the crystallization time increases. These results reveal that the relative stabilities of metal-incorporated aluminophosphate (MeAPO) molecular sieves between AFI and CHA structures depend on the type of incorporated metal ions. This work also suggests that microwave syntheses of MeAPO molecular sieves preferentially induce a kinetically favorable MeAPO phase in a short period of crystallization time. The synthesis of VAPO-5 in an alkaline condition is for the first time reported in this work. 相似文献
6.
Gin-Nae Ahn Kil-Nam Kim Seon-Heui Cha Choon-Bok Song Jehee Lee Moon-Soo Heo In-Kyu Yeo Nam-Ho Lee Young-Heun Jee Jin-Soo Kim Min-Soo Heu You-Jin Jeon 《European Food Research and Technology》2007,226(1-2):71-79
The potential antioxidant activities of three phlorotannins (phloroglucinol, eckol and dieckol) purified from Ecklonia cava collected in Jeju Island were investigated to evaluate their potential value as the natural products for foods or cosmetic
application. In this study, antioxidant activities were measured by electron spin resonance spectrometry (ESR) technique for
scavenging effects of free radicals such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), alkyl, hydroxyl (HO•) and superoxide anion radical (O2
•−) and by comet assay for protecting effects against H2O2-mediated DNA damage. The results show that all the phlorotannins have the potential DPPH, alkyl, hydroxyl and superoxide
radical scavenging activities. Especially, eckol samples scavenged around 93% of DPPH at 0.25, 0.5, 1 mg/mL of concentrations
and were higher than the other phlorotannins, such as phloroglucinol and dieckol samples. Also, protecting effects of the
phlorotannins against H2O2-mediated DNA damage increased with increased concentrations of the samples in the L5178 mouse T-cell lymphoma cell lines
(L5178Y-R). In conclusion, these results suggest that the three phlorotannins purified from E. cava have the potential inhibitory effect on H2O2-mediated DNA damage and harmful free radicals and can be used as antioxidants in cosmetic, foods and drug industry. 相似文献
7.
Hong-Joo?Lee Jin-Soo?Park Moon-Sung?Kang Seung-Hyeon?MoonEmail author 《Korean Journal of Chemical Engineering》2003,20(5):889-895
The fouling potential of the negatively charged silica sol in electrodialysis (ED) by adsorption on the surface of an anion
exchange membrane was investigated. Since the fouling potential is related to the physical and electrochemical properties
of the silica sol and anion exchange membranes, it is important to characterize the properties of silica sol and membranes.
The surface charge of silica sol was investigated by the electrophoretic mobility and its isoelectric point was determined
as pH 3. The commercial anion exchange membranes were characterized in terms of exchange capacity, water content, the zeta
potential and the electrochemical properties of the membranes using impedance spectroscopy to predict the effects on the electrodialysis
performances. Among the characterized properties, exchange capacity and some electrochemical properties of the anion exchange
membranes were rather improved after ED experiments. In the electrodialysis of solution containing silica sol, deposition
of the silica sol did not decrease the desalting performance of the anion exchange membranes because of loosely packed cake
layer on the membrane surface. 相似文献
8.
9.
Lee Jin-Soo 《Broadcasting, IEEE Transactions on》1999,45(1):116-121
This paper describes a new TV datacasting system for digital data broadcast, referred to as S-Channel, using digital modulation over the TV first audio subcarrier in Korea. The system is designed to achieve high capacity communication rates over the TV channel. I examine research and development results pertaining to a new method for on-carrier TV datacasting using the main audio subcarrier. I call it the “S-Channel” system. Interference with other stations is not an issue because it operates within the occupied bandwidth limitations of TV stations. It also does not impact video, the first audio, the second audio or VBI portions of the existing television signal. I conclude that the new TV datacasting method offers capabilities similar to those offered by proposed datacasting like Wavephore's TVT1/4 or Digiteck's D-channel while maintaining full compliance with current broadcast regulations 相似文献
10.
Pore-filling membranes using three monomers, i.e., styrene, N-vinyl pyrrolidone (VP), and divinylbenzene (DVB), are prepared
for polymer electrolyte fuel cell (PEFC) applications. A porous polyethylene (PE) film substrate is used to enhance the dimensional
stability of the prepared membranes. The proton conductivity and the water uptake of the styrene/VP/DVB membranes are similar
to those of the styrene/DVB membranes, even though their ion exchange capacity is slightly lesser than that of the styrene/DVB
membranes. Furthermore, the thermal stability of the styrene/VP/DVB membranes is higher than that of the styrene/DVB membranes,
and, for the same DVB content, the membranes containing VP exhibit better oxidative stability. VP increases the membrane’s
water-absorbing ability due to its intrinsic hydrophilic property and decreases weak α-hydrogen derived from the sulfonated
styrene. Finally, the membrane-electrode assembly (MEA) using the 80/10/10 (Styrene/VP/DVB in weight percentage) membrane
shows better performance than that using the 90/0/10 membrane. 相似文献