• Journal of the Mineralogical Society of Korea
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• v.3 no.1
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• pp.1-6
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• 1990

Clacic amphiboles along the tremolite (Tr)-tschermakite(Ts) joint were synthesized using a piston-cylinder appratus. At 750-85$0^{\circ}C$and 12-2 kb, amphibole+corundum coexist with zoisite($\pm$talc, chlorite, and Mg-staurolite), but with anorthite($\pm$cholorite, spinel, pyroxenes, and sapphirine) at lower P. At 90$0^{\circ}C$, amphibole+corundum+clinopyroxene($\pm$anorthite, forsterite, sapphirine, and garnet) are stable over the P range 12-18 kb. These amphibole-bearing assemblages are replaced at high P by clcinopyroxene+talc+chlorite+zoisite at 650-75$0^{\circ}C$, and at higher temperatures by garnet+clinopyroxene($\pm$zoisite, orthopyroxene, and Mg-staurolite). Synthetic amphiboles with Ts>~45 mol% contain as much as 0.15 excess cations per formula unit(pfu) based on 23 oxygens(anhydrous formula), whereas less tschermakitic ones are deficient in cation occupancy by up to 0.18 pfu. This trend is attributed to the 야/trioctahedral substitution in Ca-amphiboles. Compositions of synthetic amphiboles display systematic changes with P and T governed by coexisting mineral assemblages. The Ts content (=[8-Si-Na]/2) increases with increasing T( Ts/ T=~0.1 nik% K-1) in the range 750-85$0^{\circ}C$, but remains nearly constant at 850-90$0^{\circ}C$. Pressure dramatically affects the Ts content of Ca-amphiboles:it increases with P at 8-12 kb( Ts/ T=2-3 mol% K-1), but significantly decreases at 12-21 kb( Ts/ P=-2.5 mol% Kb-1). Hence, the most tschermakitic amphiboles, containing 60$\pm$5 mol % Ts, or 1.2$\pm$0.1 tetrahedral Al, occur at 12 kb and 850-90$0^{\circ}C$. Compositions of Ca-amphiboles defined by a simple reaction, 3 Tr+2 zoisite+7 corundum+H2O=5 Ts, are reversed and used to estimate thermodynamic parameters of tschermakite assuming ideal mixing of Tr-Ts solid solutions. Predicted standard molal entropy and enthalpy of tschermakite are : S$^{\circ}$of Tr-Ts solid solutions. Predicted standard molal entropy and enthalpy of tschermakite are : S$^{\circ}$=566.9$\pm$13.7 J mol-1K, -1and H$^{\circ}$=-12518.36$\pm$15.17 kJ mol.-1

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.458-465
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• 2020

Isotherms, kinetics and thermodynamic properties for adsorption of acid fuchsin (AF) dye by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration and contact time and temperature. The effect of pH on adsorption of AF showed a bathtub with high adsorption percentage in acidic (pH 8). Isothermal adsorption data were fitted to the Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models. Freundlich isothem model showed the highest agreement and confirmed that the adsorption mechanism was multilayer adsorption. It was found that adsorption capacity increased with increasing temperature. Freundlich's separation factor showed that this adsorption process was an favorable treatment process. Estimated adsorption energy by Dubinin-Radushkevich isotherm model indicated that the adsorption of AF by activated carbon is a physical adsorption. Adsorption kinetics was found to follow the pseudo-second-order kinetic model. Surface diffusion at adsorption site was evaluated as a rate controlling step by the intraparticle diffusion model. Thermodynamic parameters such as activation energy, Gibbs free energy, enthalpy entropy and isosteric heat of adsorption were investigated. The activation energy and enthalpy change of the adsorption process were 21.19 kJ / mol and 23.05 kJ / mol, respectively. Gibbs free energy was found that the adsorption reaction became more spontaneously with increasing temperature. Positive entropy was indicated that this process was irreversible. The isosteric heat of adsorption was indicated physical adsorption in nature.

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.73-79
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• 1973

The ultrasonic absorption of Dodecyl pyridinium bromide (D.P.B.) in aqueous solution has been measured at $20^{\circ}C$ over a range of frequencies between 0.1 mc and 90 mc and a range of concentrations from 5 to 100 mM. The excess absorption was observed only in the solutions the concentration of which was higher than the critical micellar concentration (c.m.c.) both in the presence and absence of salt. The excess absorption of sound and the relaxation frequencies obtained from the absorption curves show a discontinuity with the variation of the concentration of D.P.B. in the neighborhood of 60 mM. Other properties such as viscosity, conductivity and velocity of sound also exhibit such a change near the same concentration. It is concluded that a change in the properties of the micelles of D.P.B. occurs in the neighborhood of this concentration. The mechanism of the observed ultrasonic excess absorption in attributed to the reaction $M_2{\rightleftarrow}M_1+2Br^-$where$M_2$ and$M_1$are two types of micelles. The rate constants of forward and backward reactions are found to be $6.9 {\times} 10^5 sec^{-1)$and $6.7{\times}10^{10}sec^{-1}mole{-2}$ respectively. Some kinetic characteristics including free energy, enthalpy, entropy and activation energy were calculated.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.632-638
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• 2014

Batch adsorption studies including equilibrium, kinetics and thermodynamic parameters for the adsorption of new fuchsin dye using granular activated carbon were investigated with varying the operating variables such as initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. Adsorption equilibrium was mostly well described by Langmuir Isotherm. From the estimated separation factor of Langmuir ($R_L$ = 0.023), and Freundlich (1/n = 0.198), this process could be employed as an effective treatment for the adsorption of new fuchsin dye. Also based on the adsorption energy (E = 0.002 kJ/mol) from Dubinin-Radushkevich isotherm and the adsorption heat constant (B = 1.920 J/mol) from Temkin isotherm, this adsorption is physical adsorption. From kinetic experiments, the adsorption reaction processes were confirmed following the pseudo second order model with good correlation. The intraparticle diffusion was a rate controlling step. Thermodynamic parameters including changes of free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption. The change of enthalpy (92.49 kJ/mol) and activation energy (11.79 kJ/mol) indicated the endothermic nature of adsorption processes. The change of entropy (313.7 J/mol K) showed an increasing disorder in the adsorption process. The change of free energy found that the spontaneity of process increased with increasing the adsorption temperature.

• Clean Technology
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• v.20 no.1
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• pp.35-41
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• 2014

Batch adsorption studies were carried out for equilibrium, kinetic and thermodynamic parameters for quinoline yellow adsorption by granular activated carbon ($8{\times}30mesh$, $1,578m^2/g$) with varying the operating variables like initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. From estimated Langmuir constant ($R_L=0.0730{\sim}0.0854$), Freundlich constant (1/n = 0.2077~0.2268), this process could be employed as effective treatment for removal of quinoline yellow. From calculated Temkin constant (B = 15.759~21.014 J/mol) and Dubinin-Radushkevich constant (E = 1.0508~1.1514 kJ/mol), this adsorption process is physical adsorption. From kinetic experiments, the adsorption process were found to confirm to the pseudo second order model with $r^2$ > 0.99 for all concentrations and temperatures. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The activation energy value (+35.137 kJ/mol) and enthalpy change (35.03 kJ/mol) indicated endothermic nature of the adsorption process. Entropy change (+134.38 J/mol K) showed that increasing disorder in process. Free energy change found that the spontaneity of process increased with increasing adsorption temperature.

• Journal of the Korean Applied Science and Technology
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• v.8 no.2
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• pp.105-114
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• 1991

In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(${\Delta}H^0_m,\;{\Delta}S^0_m,\;{\Delta}G^0_m,$) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60$^{\circ}C, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were $7.64{\times}10^{-4}{\sim}9.13{\times}10^{-4},\;3.85{\times}10^{-4}{\sim}4.60{\times}10^{-4},\;2.00{\times}10^{-4}{\sim}2.39{\times}10^{-4},\;and\;1.07{\times}10^{-4}{\sim}1.28{\times}10^{-4}$ mol/l, respectively. Surface tension, ${\Gamma}_{CMC}$, of those were 33.49${\sim}$36.00, 34.78${\sim}$37.61, 35.49${\sim}$37.61 and 38.76${\sim}$55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60$^{\circ}C$, the change of Gibbs evergy (${\Delta}G_m$) for one methylene group ($-CH_2-$) were -0.65RT, respectively, The minus values of enthalpy change (${\Delta}H_m$) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (${\Delta}S_m$) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.

• Clean Technology
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• v.17 no.2
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• pp.97-102
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• 2011

The adsorption characteristics of amatanth dye by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of amaranth dye were carried out at 298, 308 and 318 K, using aqueous solutions with 100, 200 and 300 mg/L initial concentration of amatanth. It was established that the adsorption equilibrium of amaranth dye on granular activated carbon was successfully fitted by Langmuir isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 100, 200 and 300 mg/L initial concentration of amatanth, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The estimated values for standard free energy were -5.08 - -8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a spontaneous process. The positive value for enthalpy, 38.89 kJ/mol indicates that adsorption interaction of amatanth dye on activated carbon is an endothermic process.

• Analytical Science and Technology
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• v.12 no.5
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• pp.387-396
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• 1999

The retention behavior of Cot(II)-dithiocarbamate(DTC) chelates in reversed phase high performance liquid chromatography was investigated. Enthalpy and entropy of chelates transfer from the mobile phase to the stationary phase were calculated from retention data using van't Hoff plots. The dependence of In k' on enthalpy was decreased with increasing organic solvent ratio on the mobile phase. The compensation temperatures(${\beta}$) calculated from the slope of $-{\Delta}H^0$ vs In k' were in the range of 756.3-888.5 K. From these results. it was found that the retention mechanism of DTC chelates was invariant under the various temperatures and was largely affected by the solvophobie effect. Liniear relationship between S index and log k' in emprical retention equation, $log\;k^{\prime}=log\;{k_w}^{\prime}-S_{\varphi}$ showed that S index was influenced mainly by the interaction between DTC chelates and the mobile phase.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.44-52
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• 1980

Ionic dissociation rates of $\alpha$-chlorobenzyl ethyl ether in each solvent of toluene-$d_8$ and carbon tetrachloride were measured by the method of dynamic NMR spectroscopy. The spin system of these 1H NMR spectra was $AB_3$. The theoretical spectrum was calculated by computer simulation of dynamic NMR spectra, which agreed very well with observed spectra. From this computer simulation, the ionic dissociation rate constant k was obtained, and by Eyring plot with it, slope and intercept length was gained, from which kinetic parameters were calculated.The easiness of ionic dissociation depended upon solvent polarity. Activation enthalpy was 4.7 kcal/mole in toluene-$d_8$, 10.7 kcal/mole in carbon tetrachloride, and activation entropy was -35. 8 e.u. in toluene-$d_8$, -14.4 e.u. in carbon tetrachloride. It was understood that though the ${\Delta}H^{neq}$ value was small, this ionic dissociation had an easier procession in nonpolar solvents with increasing temperatures. Considering that the ionic dissociation could be thought as the first step of $S_N1$ mechanism, attention might be paid to the results that the value of ${\Delta}S^{neq}$ had a large negative value in comparison with a small ${\Delta}H^{neq}$.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.1-7
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• 2012

Natural gas through pipeline is supplied to consumers after its pressure gets down compulsorily. The waste pressure energy of this process can be restored by use of turbo expander which can produce electricity. So, turbo expander conducts two functions - pressure reduction and power generation. The power amount is the enthalpy difference between the inlet and outlet states. The five main factors which affect economic profit are facility price, produced power amount, pre-heating amount, electricity cost, and fuel gas cost. Power generation depends mainly on flow amount because inlet and outlet states are fixed. A methodology to estimate economy in irregular flow pattern is proposed and using this way, a case study was carried out.