• Journal of the Korean Chemical Society
• /
• v.16 no.1
• /
• pp.1-5
• /
• 1972

The adsorption kinetics on a membrane filter have been studied by an introduction of acid or alkali in yttrium-90 solution. The change of the adsorption in the filtration process was determined by the filtrate activities with using a microsyringe filter holder connected with a syringe. The over all reaction rate obeyed a reversible first order reaction, and the rate constants thus obtained, showed the values of $k_1$ = 0.12 $sec^{-1}$ and $k_1'$ = 0.039 $sec^{-1}$. As a result of the present studies, it would be reasonable that the rate determining step of the adsorption reaction was the hydrolysis reaction of the adsorbed yttrium ions.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.9
• /
• pp.1335-1338
• /
• 2005

Thianthrene cation radical perchlorate ($Th^{+{{\cdot}}}{ClO_4}^-$) reacted readily with two isomeric thiols, benzylthiol (1) and 4-methylbenzenethiol (7) in an acetonitrile solution at room temperature. From the reaction of 1, the major products, N-benzylacetamide (4) and benzyl sulfide (5), are characteristic of benzyl carbocations while the minor one, benzyl disulfide (6) implies free radical component of the reaction. It is unprecedented that the formation of a benzyl carbocation was caused by the extrusion of sulfur atoms from benzyl sulfur cations (3). In contrast, from the reaction of 7, only p-tolyl disulfide (10) was obtained from both sulfur radicals and cations. In the reaction of 7 the thio-extrusion was not observed from the p-tolyl sulfur cation (9). A thianthrene cation radical ($Th^{+{{\cdot}}}$) was reduced quantitatively to thianthrene (Th) in both reactions.

• Macromolecular Research
• /
• v.13 no.3
• /
• pp.180-186
• /
• 2005

A novel bifunctional dye composed of spirobenzopyran and a cinnamoyl moiety was prepared and its photochromic behavior under the illumination of monochromatic UV light was investigated. This colorless bifunctional dye exhibits typical photochromism in both the film and in solution, through the structural and geometrical transformation from spirobenzopyran to merocyanine accompanied by a photocrosslinking reaction between the cinnamoyl moieties. Two kinds of photochemical reaction were selectively achieved by irradiation with monochromatic UV light at wavelengths of 275 and 365 nm, respectively. The effect of the selective photochemical reaction on the photochromism of the dye and its decaying behavior was investigated.

• Journal of the Korean Society of Tobacco Science
• /
• v.11 no.2
• /
• pp.203-210
• /
• 1989

Leucine and isoleucine were reacted with glucose in a propylene glycol solution and volatile compounds produced from these reaction were analysed by gas chromatography and mass spectrometry. A total of 24 compounds were identified in the leucine reaction volatiles and the major components were 2-isopropyl-5-methyl-2-hexenal, methylbutyraldehyde PGA, butyraldehyde PGA, 5-methylfur-fural, isopropylmethylhexenal PGA and 2-acetylpyrrole. From the isoleucing reaction volatiles, 20 compounds were identified and the major components were methylbutyraldehyde PGA, butyraldehyde PGA and 2-acetylpyrrole. The amino acids chosen for this study were considered as giving fruity and cocoa aroma when heated with glucose.

• Textile Coloration and Finishing
• /
• v.16 no.2
• /
• pp.34-40
• /
• 2004

This study was conducted to remove the reactive dyes by the Ozone demand flask method which are one of the main pollutants in dye wastewater, Ozone oxidation of three kinds of the reactive dyes was examined to investigate the reactivity of dyes with ozone, Trihalomethane formation potentials(THMFPs), competition reaction and ozone utilization on various conditions for single- and multi-solute dye solution. Concentration of dyes was decreased continuously with increasing ozone dosage in the single-solute dye solutions. THMFPs per unit dye concentration were gradually increased with increase of ozone dosage. By the result of THMFPs change with reaction time, THMFPs were rapidly decreased within 1 minute in single-solute dye solutions. Dey were increased after 1 minute of reaction time, and then they were consistently decreased again after longer reaction time. Competition quotient values were calculated to investigate the preferential oxidation of individual dyes in multi-solute dye solutions. Competition quotients$(CQ_i)$ and values of the overall utilization efficiency, no$_3$, were increased at 40mg/1 of ozone dosage in multi-solute dye solutions.

• Journal of Surface Science and Engineering
• /
• v.32 no.2
• /
• pp.172-181
• /
• 1999

The effect of the DMAB concentration, temperature, deposition time, and stabilizer concentration on the precipitation reaction of the electroless nickel plating using dimethylamine borane (DMAB) as reducing agent was investigated to by the weight gain and electrochemical method. The deposition rate was dependent with DMAB concentration. The polarization resistance of the precipitation reaction was reduced with DMAB concentration. The precipitation reaction rate of Ni-B deposits was controlled by the oxidation rate of DMAB as the source of electron. The boron content of the deposit was constant at about 5.5wt%, even when DMAB concentration in the solution was increased. The effect of temperature and stabilizer ($Pb(NO_3)_2$) concentration on deposition rate was shown to have co-dependent behaviors.

• Journal of Electrochemical Science and Technology
• /
• v.8 no.2
• /
• pp.146-154
• /
• 2017

In this study, copper (II) oxide was prepared for use in a copper electroplating solution. Copper chloride powder and copper (II) oxide are widely used as raw materials for electroplating. Copper (II) oxide was synthesized in this study using a two-step chemical reaction. Herein, we developed a method for the preparation of copper (II) oxide without the use of sintering. In the first step, copper carbonate was prepared without sintering, and then copper (II) oxide was synthesized without sintering using sodium hydroxide. The optimum amount of sodium hydroxide used for this process was 120 g and the optimum reaction temperature was $120^{\circ}C$ regardless of the starting material.

• Journal of the Korean Chemical Society
• /
• v.40 no.5
• /
• pp.302-307
• /
• 1996

Diethanolamine dithiocarbamate is known to react with dichlorobis(ethylenediamine)cohalt(Ⅲ) chloride to form [Co(dtc)3](dtc=diethanolamine dithiocarbamate) in which two sulfur atoms of the dithiocarbamate are bound to cobalt. The complex is moderately soluble in acetone, but sparingly soluble in carbon disulfide. Kinetics and mechanisms of the reaction of dichlorobis(ethylenediamine)cobalt(Ⅲ) chloride with diethanolamine dithiocarbamate have been studied in aqueous solution. Activation parameters have been calculated from the kinetic data for the reaction and from these results a possible mechanism for the reaction has been proposed.

• Journal of Sensor Science and Technology
• /
• v.14 no.5
• /
• pp.291-296
• /
• 2005

In this paper, the PDMS based micromixer having 3-dimension triangular structure has been developed for the reaction of samples in the micro volume. The mixing efficiency was measured according to the change of Reynolds number (Re: 0.08, 0.8, 8, 16) and channel height (100, 200, $300{\mu}m$). Total length of mixing region is 7.4 mm and the measured mixing efficiencies at the outlet were over 85 %. Within the mixing length 2.4 mm, the mixing efficiencies were more than 70 % at any Reynolds numbers, and this indicates the strong mixing has occurred inside the mixing channel due the triangular structures. By employing these 2 mixers, we have fabricated the microreactor to detect the glucose-catalysts reaction. The microreactor showed good reactivity of glucose and enzymes with the small amount of sample solution.

• Journal of Surface Science and Engineering
• /
• v.22 no.3
• /
• pp.118-127
• /
• 1989

The rate of electrodeposition Zinc-nickel alloy on to electrolytic ione in sulface solution both under an inter and air atmospherss has studied by use of a rotating disc geometry. The kinetics shows 1st order reaction, and the rate constants are proportional to the square root of rpm, however, they are less than the valuse suggested by Levich. The rate constants of zinc deposition approach the total mass transfer rate constants with increasing potential and deviate with increasing rotaing speed, but those of nickel deposition are constant. Below $40^{\circ}C$ the activation engrgies of zinc deposition and nikel deposition were 4.4Kcal/mol and 6.3Kcal/mol respectively. There results show that overall reaction rate of zinc-nickel plaeting is controlled by mixed reaction and zinc deposotion is more affected by mass transfer reaction than nickel. The current density for the zinc-nickel plating was less in an air atmosphere than in a nitrogen atmosphere. The cathode efficiency increased with decreasing cathode rotating speeds, potentials, and increasing temperatures. Zzinc-nickel platings are more improved in microhardnss than zinc platings.