• Journal of the Korean Chemical Society
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• v.18 no.2
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• pp.126-131
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• 1974

Trioctylamine-and tricaprylylmethylammonium chloride-tungstate salts have been prepared by solvent extraction from the sodium tungstate solution of various acidities(pH = 2, 4, 6). The molecular weights of the amine-tungstate salts thus obtained could be cryoscopically measured in benzene by means of a home-built Wheatstone bridge utilizing thermistor with sensitivity of 1/$4000^{\circ}C$. The cryoscopic data along with the results of chemical analysis and infrared spectra of the salts indicate that the amine-tungstates prepared at pH = 2 and 4 are all metatungstate whereas the salt obtained at pH = 6 is an unknown form quite different from the expected paratungstate.R = 0.14. By hydrogen bonding a guanidyl nitrogen of a sulfaguanidine molecule is linked to the sulfonyl oxygens of the other molecules indirectly through two different water molecules. The role of water molecule is both a .
nor and an acceptor in hydrogen-bonding formation and these hydrogen bonds are tetrahedrally o？ented. The hydrogen-bonding networks form infinite molecular layers parallel to (001) plane.

• Analytical Science and Technology
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• v.18 no.3
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• pp.201-205
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• 2005

Tri-octyl amine (TOA) is used in solvent extraction process for radioactive waste. This compound may be degraded to di-octyl amine (DOA), mono-octyl amine (MOA) by radioactive materials. Amount of TOA, DOA and MOA in TOA must be monitored because they production of these compounds means degradation of which leads to a decrease in the extraction yield. Retention behavior for TOA, DOA and MOA are studied with Phenomenex LUNA-$C_{18}$ ($4.6mm{\times}25cm$) analytical column and $CH_3OH:H_2O$ (50 mmol $CH_3COONH_4$) eluent by liquid chromatography. Optimum condition for these compounds is $CH_3OH:H_2O$ (50 mmol $CH_3COONH_4$) = 85 : 15 ratio. TOA, DOA and MOA compounds is well separated within 20 minute. Dynamic range is $30{\sim}160{\mu}g/mL$ for TOA, $5{\sim}100{\mu}g/mL$ for DOA and $0.1{\sim}5{\mu}g/mL$ for MOA, respectively. The detection limit are $0.1{\mu}g/mL$ for TOA, $1{\mu}g/mL$ for DOA (in SCAN mode) and $0.1{\mu}g/mL$ for MOA (in SIM mode) in this system with $20{\mu}L$ sample loop.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.267-271
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• 2013

Test bed studies with highly efficient amine $CO_2$ solvent (KoSol-4) developed by KEPCO research institute were performed. For the first time in Korea, evaluation of post-combustion $CO_2$ capture technology to capture 2 ton $CO_2$/day from a slipstream of the flue gas from a coal-fired power station was performed. Also the analysis of solvent regeneration energy was conducted to suggest the reliable performance data of the KoSol-4 solvent. For this purpose, we have tested 5 campaigns changing the operating conditions of the solvent flow rate and the stripper pressure. The overall results of these campaigns showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate: 90%) suggested by IEA-GHG and that the regeneration energy of the KoSol-4 showed about 3.0~3.2 GJ/$tCO_2$ which was, compared to that of the commercial solvent MEA (Monoethanolamine), about 25% reduction of regeneration energy. Based on these results, we could confirm the good performance of the KoSol-4 solvent and the $CO_2$ capture process developed by KEPCO research institute. And also it was expected that the cost of $CO_2$ avoided could be reduced drastically if the KoSol-4 is applied to the commercial scale $CO_2$ capture plant.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.185-192
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• 1976

Equivalent conductances of ammonium salts such as $NH_4Cl,\;CH_3NH_3Cl,\;(CH_3)_2NH_2Cl,\;(CH_3)_3NHCl\;and\;(CH_3)_4NCl$ have been measured in methanol-water mixtures of various composition (0.0${\sim}$0.6-mole frcation: m. f.) in the concentration range from 0.01 to 0.04 M at $25^{\circ}C$, and limiting equivalent conductances (${\Lambda}_0$) are determined by the analysis of Fuoss Onsager's semiempirical equation.The experimental results are discussed in terms of varing the size of ${\Lambda}_0$ due to the salts species and solvent composition. It has been observed in quite common over all salts that ${\Lambda}_0$ decreases with the increase of m. f. methanol, and the maximum decrement in ${\Lambda}_0$ shows between water and 0.1 m. f., while the plot of ${\Lambda}_0$ vs. m. f. goes through a minimum at 0.4 m. f. and then turns slightly upward. On the other hand, the ${\Lambda}_0$ decrease with the increase of the size of ammonium cation and the larger values ${\Lambda}_0$ are showed in comparison with those of values observed for the corresponding $n-RNH_3Cl$ under the same experimental procedure. All these behaviors are considered to be closely correlated with the structures of solvents and solutes and the significant similarities are compared with the behaviors of partial molar volumes for amine salts in same solvent system.

• Journal of Pharmaceutical Investigation
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• v.35 no.2
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• pp.95-99
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• 2005

Mucoadhesive microspheres were prepared by interpolymer complexation of chitosan with poly(acrylic acid) (PAA) and solvent evaporation method to increase gastric residence time. The chitosan-PAA complex formation was confirmed by differential scanning calorimetry and swelling study. The DSC thermogram of chitosan-PAA microspheres showed two exothermic peaks for the decomposition of chitosan and PAA. The swelling ratio of the chitosan-PAA microspheres was dependent on the pH of the medium. The swelling ratio was higher at pH 2.0 than at neutral pH. The results indicated that the microspheres were formed by electrostatic interaction between the carboxyl groups of PAA and the amine groups of chitosan. The effect of various process parameters on the formation and morphology of microspheres was investigated. The best microspheres were obtained when 1.5% of the high molecular weight chitosan and 0.3% of PAA were used as an internal phase. The optimum internal phase volume was 7%. The com oil was used as the external phase of emulsion, and span 80 was used as the surfactant. The prepared microspheres had spherical shape.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.380-385
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• 2009

The absorption rate of carbon dioxide with 2-amino-2-methyl-1-propanol(AMP) was measured in such non-aqueous solvents as methanol, ethanol, n-propanol, n-butanol, ethylene glycol, propylene glycol, and propylene carbonate, and in water at 298 K and 101.3 kPa using a semi-batch stirred tank with a plane gas-liquid interface. The overall reaction rate constant, obtained under the condition of fast reaction regime, from the measured rate of absorption was used to get the elementary reaction rate constants in complicated reactions represented by reaction mechanism of carbamate formation and the order of overall reaction of $CO_2$ with amine. The correlation between the elementary reaction rate constant and the solubility parameter of the solvent was also presented.

• Resources Recycling
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• v.7 no.2
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• pp.9-15
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• 1998

Recovery af molybdenum in spent desulfuriring catalyst of petrochemical industries was studied from MfGnatc solulion which is a resultant of firstly remvercd vanadium by wet processes. In order to separate and recover molybdenum from upper mentioned rafinatz solution containing several mctal ions, such as molybdenum (1,100 ppm), vanadium (150 ppm), aluminium (19 ppm), and nickel (33 ppm), either adsorption technique by chelate resin or solvent extr~ction by tertiary amine as extractant was applied. In case of adsorption method, palyamine type chelate resin showed the highest selectivily far molybdenum ion up lo 60 ddm' of ancentration aftcr eluting with 3.0 rnolld~n' of NH,OH. On the othcr hand. molybdenum ion wa cffectlvely cxtractcd in Ule whole ranges of equilibrilrm pR by solvent extraction method with 10 ~01%-alamine 336 which was pretreated with 2N-HCI

• Resources Recycling
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• v.30 no.5
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• pp.32-37
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• 2021

Thorium extraction and possible separation from monazite leaching solution was studied. Primary amine Primene JM-T was select ed for t horium ext ract ion processing. Various experiment s were t est ed and est ablished for t he t horium liquid -liquid extraction process. The screening of extractant, lower pH conditions, extractant variation and extraction isotherms construction, and finally, stripping studies were established.

• Elastomers and Composites
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• v.54 no.3
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• pp.209-219
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• 2019

It is important to analyze crosslink densities of rubber articles because the physical properties are dependent on the crosslink densities. In this paper, analytical techniques for the measurement of crosslink densities of rubber vulcanizates are described. The most widely used method to measure the crosslink density is a swelling method combined with the Flory-Rehner equation. Application of the interaction parameter (${\chi}$) of rubber and swelling solvent is critical because the crosslink density is absolutely dependent on the ${\chi}$ value. Methods for obtaining ${\chi}$ employ not only solubility parameters of the polymer and swelling solvent but also inverse gas chromatography (IGC). The solubilities of rubbers can be obtained using micro differential scanning calorimetry (${\mu}DSC$), intrinsic viscosity measurement, and UV-visible spectroscopy. Nuclear magnetic resonance (NMR) spectroscopy has been also used for the measurement of the crosslink density using the $T_2$ relaxation time, which is determined by spin-spin relaxation in solid-state NMR. For sulfur-cured rubber vulcanizates, crosslink densities according to the crosslink types of mono-, di-, and polysulfides are measured by treating the rubber samples with a chemical probe composed of thiol and amine compounds. Measurement methods of physical crosslinking by filler, crystallization, and ionic bonding have also been introduced.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1199-1203
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• 2010

Second-order rate constants ($k_N$) have been measured spectrophotometrically for Michael-type reactions of 1-(X-substituted phenyl)-2-propyn-1-ones (2a-f) with a series of alicyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The $k_N$ value increases as the incoming amine becomes more basic and the substituent X changes form an electron-donating group (EDG) to an electron-withdrawing group (EWG). The Br${\o}$nsted-type plots are linear with ${\beta}_{nuc}$ = 0.48 - 0.51. The Hammett plots for the reactions of 2a-f exhibit poor correlations but the corresponding Yukawa-Tsuno plots result in much better linear correlations with ${\rho}$ = 1.57 and r = 0.46 for the reactions with piperidine while ${\rho}$ = 1.72 and r = 0.39 for those with morpholine. The amines employed in this study are less reactive in MeCN than in water for reactions with substrates possessing an EDG, although they are ca. 8 pKa units more basic in the aprotic solvent. This indicates that the transition state (TS) is significantly more destabilized than the ground state (GS) in the aprotic solvent. It has been concluded that the reactions proceed through a stepwise mechanism with a partially charged TS, since such TS would be destabilized in the aprotic solvent due to the electronic repulsion between the negative-dipole end of MeCN and the negative charge of the TS. The fact that primary deuterium kinetic effect is absent supports a stepwise mechanism in which proton transfer occurs after the rate-determining step.