• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.715-720
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• 2004

Amineterminated, ethylenediamine core polyamidoamine starburst dendrimers of generation 2 (G2), generation 4 (G4) and generation 6 (G6) have been successfully surface-modified via an amide coupling reaction with 4-ethyl, 4'-(3-propionic) bipyridinium cation and the electrochemical behavior of the resulting dendrimers were investigated in aqueous potassium chloride electrolyte solutions. The 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide-mediated reaction resulted in 25-39% end-group functionalization. The water-soluble 4-ethyl, 4'-(3-propylamide) bipyridinium dibromide dendrimers (G2-V2+, G4-V2+ and G6-V2+) were characterized by $^1H$ NMR and UV-Vis spectroscopic methods. The cyclic voltammetric and chronoamperometric experiments were performed to determine the diffusion coefficient and the number of electrons transferred in the process of the first reduction of the viologen-functionalized dendrimers. Adsorption of viologen-functionalized dendrimers at electrode surface was evidenced in the voltammograms. Experimentally determined diffusion coefficients were in good agreement with the values expected from the Stokes-Einstein relation, while the number of electrons transferred concurred with the extent of functionalization determined by $^1H$ NMR and UV-Vis spectra.

• Journal of Sensor Science and Technology
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• v.17 no.1
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• pp.9-14
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• 2008

In this paper, the gas responses of tungsten oxide films prepared by anodic reaction was discussed. Sensing electrodes and heating electrodes were patterned by photolithography method on quartz substrate. Porous tungsten oxide was fabricated in electrolyte solutions of 5 % HF (HF :$C_2H_6OH:H_2O$=3 : 2 : 20) by anodic reaction. The anodic reaction with metal (platinum wire) as a cathode and the sensing device as an anode was conducted under the various reaction times (1-10 min) at 10 mA/$cm^2$ The surface structure and morphology of the fabricated sensor have been analysed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). All the peaks of XRD results were well indexed to the pure phase pattern. The average diameter of the porous tungsten oxide surface were ranged about 100 nm. The fabricaed sensor showed good sensitivity to 200 ppm toluene at operating temperature of $250^{\circ}C$.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.127-142
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• 2013

In order to investigate the significance of "salting-out" and "pore swelling" effects on the nanofiltration of neutral solutes, rejection properties of two NF ceramic and polymeric membranes were studied with single polyethyleneglycol (PEG) solution and mixed PEG/inorganic electrolyte solutions. For both membranes, the rejection rate of PEG was found to decrease significantly in the presence of ions. In the case of the ceramic membrane (rigid pores), this phenomenon was imputed to the sole partial dehydration of PEG molecules induced by the surrounding ions. This assumption was confirmed by the lowering of the PEG rejection rates which followed the Hofmeister series. Experimental data were used to compute the resulting decrease in the Stokes radius of PEG molecules in the presence of the various salts. Concerning the polymeric membrane, the decrease in the rejection rate was found to be systematically higher than for the ceramic membrane. The additional decrease was then ascribed to the swelling of the pores. The experimental data of rejection rates were then used to compute the variation in the mean pore radius in the presence of the various salts. The pore swelling phenomenon due to accumulation of counterions inside pores was supported by electrokinetic charge density measurements.

• Fashion & Textile Research Journal
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• v.13 no.5
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• pp.790-796
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• 2011

This study was designed to investigate the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil under various solutions. The detergency of the particulate soil was determined by adhesion of particle to fabric and its removal from fabric separately. The PET fabric and ${\alpha}-Fe_2O_3$were used as materials of textile and model of particulate soil, respectively. The detergency was investigated as a function of surfactants concentration, ionic strength, kinds of electrolyte and mole numbers of oxyethylene ether of nonionic surfactant in different ratio of anionic/nonionic surfactant mixture. Although some deviations exist, the adhesion of particle to fabric generally increased with decreasing its removal from fabric. The detergency of particulate soil on PET fabric was relatively higher in anionic/nonionic surfactant mixed solution than in each single surfactant solution, but the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil was low. Generally the detergency of particulate soil on fabric was at its maximum at 0.1% surfactant concentration, $1{\times}10^{-3}$ ionic strength, $Na_5P_3O_{10}$ electrolytes and 10 mole numbers of oxyethylene ether of nonionic surfactant, regardless of ratio of anionic/nonionic surfactant mixture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.256-257
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• 2005

We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. The viologen derivative exist in three redox states, namely. These redox reactions are highly reversible and can be cycled many times without significant side reactions, respectively. We studied the characteristics of charge transfer using different electrolyte solutions by electrochemical quartz crystal microbalance (EQCM). From the data, the redox peak currents were nearly equal charges during redox reaction and existed to an excellent linear interrelation between the scan rates and first redox peak currents. The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redox reactions.

• Analytical Science and Technology
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• v.8 no.1
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• pp.25-32
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• 1995

Determination method of trace thioglycolate has been studied by adsorptive stripping voltammetry. Copper(II)-thioglycolate complex is adsorbed at the hanging mercury drop electrode and stripped during cathodic scan. Electrolyte was used pH 6.5 phosphate and pH 9.5 borate buffer solutions. Optimal conditions were a copper(II) concentration $1{\times}10^{-4}M$, an adsorption accumulation potential -0.2V, an adsorption accumulation time 60 sec and a scan rate 20mV/sec. A detection limit of $1{\times}10^{-9}M$ thioglycolate was obtained. The method was applied to the determination of thioglycolate in cold wave fluids and depilating creams.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.69-75
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• 2006

The microbubbles were used in various fields, such as turbulent control, drag reduction, material science and life science. The X-ray PTV using X-ray micro-imaging technique was employed to mea-sure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Micro-bubbles of $10{\sim}60{\mu}m$ diameter moving upward in an opaque tube (${\phi}$=2.7mm) were tested. Due to the different refractive indices of water and air, phase contrast X-ray images clearly show the exact size and shape of over-lapped microbubbles. In all of the working fluids tested (deionized water, tap water, 0.01 and 0.10M NaCl solutions), the measured terminal velocity of the microbubbles rising through the solution was proportional to the square of the bubble diameter. The rising velocity was increased with increasing mole concentration. The microbubble can be useful as contrast agent or tracer in life science and biology. The X-ray PTV technique should be able to extract useful information on the behavior of various bio/microscale fluid flows that are not amenable to analysis using conventional methods.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.2
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• pp.129-136
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• 2001

An investigation on the A/V(ampere/volt) gradient according to the concentration and the kind of solution in a electrolyzer is carried out to obtain the basic data on the ultrasonic application for the efficiency elevation of the hydrogen fuel production. KOH is selected as an electrolyte and concentrations are 0%, 10%, 20% and 30%. The solutions are city water, city water with nitrogen. distilled water and distilled water with nitrogen. The Electrochemical analyzer(BAS Co.) is used as a measuring device to observe the A/V gradient. And the limit of volt is from -3000mV to +3000mV. The 28kHz magnetic transducer is selected to give them ultrasonic forcing. In results, it is clarified that ultrasonic influences the A/V gradient in the electrolytic solution.

• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.357-362
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• 1973

The polarographic behaviors of Pb(Ⅱ), Cd(Ⅱ) and Cu(Ⅱ) in histidine solutions were studied at ionic strength $({\mu})$ of 0.1 with the use of $NaClO_4$ as a supporting electrolyte. The formation constants of the mixed-ligand complexes of Pb(Ⅱ), Cd(Ⅱ) and Cu(Ⅱ) were calculated by Schaap's method in the presence of both histidine and hydroxide ion. The results of the electrode reactions in the systems are also discussed.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.121-123
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• 1965

Polarographic studies of Ni(II) ion complexed with monoethanolamine, MEA, in aqueous solution have been carried out using sodium perchlorate as a supporting electrolyte. With use of D. C. and A. C. polarograms polarographic behaviors of the complex have been discussed. The wave obtained from basic solutions are found to be well defined and reversible, while reduction of the complex at pH smaller than 8.8 seems to be kinetic controlled with different complex species. Reducing species of the complex on the mercury electrode is determined to be $Ni(MEA)_3OH$ instead of $Ni(MEA)_2(OH)_2$ which is reported by other workers. Overall stability constant of $Ni(MEA)_3OH$ is obtained to be $10^{20}.$