• Clean Technology
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• v.26 no.2
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• pp.122-130
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• 2020

The isotherm, kinetic, and thermodynamic parameters of reactive blue 4 adsorbed by activated carbon were investigated for activated carbon dose, pH, initial concentration, contact time, and temperature data. The adsorption of the RB 4 dye by activated carbon showed a concave shape in which the percentage of adsorption increased in both directions starting from pH 7. The isothermal adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms. Both Freundlich and Langmuir isothermal adsorption models fit well. From determined Freundlich separation factor (1/n = 0.125 ~ 0.232) and Langmuir separation factor (R_L = 1.53 ~ 1.59), adsorption of RB 4 by activated carbon could be employed as an effective treatment method. The constant related to the adsorption heat (B_T = 2.147 ~ 2.562 J mol^-1) of Temkin showed that this process was physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good agreement. The results of the intraparticle diffusion model showed that the inclination of the first straight line representing the surface diffusion was smaller than that of the second straight line representing the intraparticle pore diffusion. Therefore, it was confirmed that intraparticle pore diffusion is the rate-controlling step. The negative Gibbs free energy change (ΔG = -3.262 ~ -7.581 kJ mol^-1) and the positive enthalpy change (ΔH = 61.08 kJ mol^-1) indicated the spontaneous and endothermic nature of the adsorption process, proving this process to be spontaneous and endothermic.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.614-620
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• 1999

The critical micelle concentration (CMC) and the counterion binding constant (${\beta}$) at the CMC of the mixtures of Dodecylpyridinium chloride (DPC) and Tetradecyltrimethylammonium bromide (TTAB) have been determined from the concentration dependence of electrical conductance at various temperatures from $4^{\circ}C$ to $36^{\circ}C$. Thermodynamic parameters (${\Delta}C_p$, ${\Delta}G^o_m$, ${\Delta}H^o_m$ and ${\Delta}S^o_m$), associated with the micelle formation of DPC/TTAB mixtures, have been estimated from the temperature dependence of CMC and ${\beta}$values. The measured values of ${\Delta}C_p$ and ${\Delta}G^o_m$ are negative but the values of ${\Delta}S^o_m$ are positive in the whole measured temperature region. The values of ${\Delta}H^o_m$ are positive at low temperature region and negative at high temperature region. The results show that all of the thermodynamic parameters are dependent on temperature and mole fraction of DPC(${\alpha}_DPC$).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.224-234
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• 1997

In order to make high purity materials including low contents of interstitial impurities, 70 ㎾ electron beam melter was manufactured. The sponge Ti and Ti-6Al-4V alloy were required and melted by electron beam melter. Based on the experimental results of sponge Ti refining by electron beam melting, the purity of Ti was increased for 180 seconds but thereafter did not significantly vary. In addition, it was found that with number of melting, the purity of Ti did and vary but the yield of Ti was decreased. As a results of Ti refining, high purity Ti of 3N (99.9 wt%) could be obtained including interstitial impurities with total contents of which were maximum 900 ppm. From the experimental results of Ti-6Al-4V alloy electron beam melting, the amounts of Al loss could be estimated through thermodynamic data calculated from the regular solution model and the model of solute removal kinetics and the alloy composition calculated from the models was in accord with the experimental composition of the alloy, It took 10 minutes to make Ti-29Al-4V alloy calculated from the model into Ti-6Al-4V alloy and the composition of Ti-6Al-4V alloy was very homogeneous.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.592-599
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• 2018

The kinetics and thermodynamics of the adsorption of acid blue 40 from an aqueous solution by activated carbon were examined as a function of the activated carbon dose, pH, temperature, contact time, and initial concentration. The adsorption efficiency in a bathtub was increased at pH 3 and pH 11 due to the presence of sufonate ions ($SO_3{^-}$) and amine ions ($NH_2{^+}$). The equilibrium adsorption data were fitted to the Langmuir, Freundlich and Temkin isotherms. The results indicated that the Langmuir model provides the best correlation of the experimental data. The separation factor of the Langmuir and Freundlich model showed that the adsorption treatment of acid blue 40 by activated carbon could be an effective adsorption process. The adsorption energy determined by the Temkin equation showed that the adsorption step is a physical adsorption process. Kinetics analysis of the adsorption process of acid blue 40 on activated carbon showed that a pseudo second order kinetic model is more consistent than a pseudo second order kinetic model. The estimated activation energy was 42.308 kJ/mol. The enthalpy change (80.088 J/mol) indicated an endothermic process. The free energy change (-0.0553 ~ -5.5855 kJ/mol) showed that the spontaneity of the process increased with increasing adsorption temperature.

• Journal of the Korean Chemical Society
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• v.42 no.5
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• pp.519-525
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• 1998

The critical micelle concentration $(CMC^{\ast})$ and the counterion binding constant (B) in a micellar state of the mixed surfactant systems of dodecylpyridinium chloride (DPC) with dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and cetyldimethylethylammonium bromide (CDEAB) were determined at $25^{\circ}C$ as a function of ${\alpha}_1$ (the overall molc fraction of DPC) by the use of electric conductivity method. Various thermodynamic parameters $(X_{i},\;{\gamma}_{I},\;C_{i},\;a^{M}_{i}, \beta,\;{\Delta}H_{mix}, \;and\; {\Delta}G^{o}_{m})$ for the micellization of DPC/DTAB, DPC/TTAB, and DPC/CDEAB mixtures were calculated and analyzed for each system by means of the equations derived from the pseudophase separation model. The results show that the DPC/DTAB mixed system has the greatest deviation and the DPC/CDEAB mixed system has the smallest deviation from the ideal mixed micellar model.

• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.538-542
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• 1995

The stability constant and the thermodynamic parameters of the hydrazide Schiff base ligands such as N,N'-oxalylbis(salicylaldehydehydrazone)(OBSH), N,N'-malonylbis(salicylaldehydehydrazone)(MBSH), and N,N'-succinylbis(salicylaldehydehydrazone)(SBSH) with dioxouranium(Ⅵ) ion have been determined by potentiometry in 95% DMF solution at various temperatures. The order of stability constants increased SBSH

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.590-593
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• 2007

물을 함유한 공극 크기 6, 30, 100 nm의 실리카겔에 이산화탄소 및 메탄을 반응시켜 온도$0{\sim}4$ $^{\circ}C$, 압력 $15{\sim}40$ bar 의 범위에서 가스 하이드레이트 생성속도를 측정하였다. 공극 크기가 작아짐에 따라 특정 온도에서의 평형압력이 높아지는 열역학적 특성을 감안하여 통일한 압력차 (평형압력과 실험압력의 차)를 얻을 수 있도록 조건을 설정하였다. 이산화탄소의 경우 통일 온도에서 하이드레이트 생성속도는 일반적으로 압력이 높아짐에 따라 가속되는 것을 알 수 있었다. 단위 물 당 포집되는 이산화탄소의 양은 최대 1.0을 넘지 못하였다. 또한 하이드레이트 생성을 위해 필요한 유도시간 (induction time)이 2내지 8시간 수준으로 매우 길었다. 공업적인 하이드레이트 이용을 위해서는 빠른 생성속도가 필요한 만큼 유도시간을 단축, 없애기 위해 계면활성제로 황산 도데실 나트륨 (sodium dodecyl sulphate)이 첨가된 수용액을 이용하였다. 계면활성제가 포함된 수용액에서의 하이드레이트 생성은 유도시간이 사라져 매우 빠르게 바뀌었고, 포집되는 이산화탄소도 15% 정도 증가되었다. 메탄의 경우에는 공극 크기가 작아질수록 하이드레이트 생성속도 및 가스 포집도가 저하되는 결과를 보였다. 이산화탄소의 경우와는 다르게 유도시간이 나타나지 않았으며 비교적 높은 가스 포집도를 얻기 위해서는 평형압력과 실험압력의 차이가 최소 2.0MPa 이상이어야 했다.

• Journal of the Korean Chemical Society
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• v.24 no.6
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• pp.405-412
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• 1980

The effect of pressures and temperatures on the stabilities of the mesitylene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of complexes were measured at 25, 40 and $60^{\circ}C$ under 1∼1600 bars. The equilibrium constant of the complex was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift observed a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.245-253
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• 1978

The effect of pressures and temperatures on the stabilities of the p-xylene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of complexes were measured at 25, 40 and $60^{\circ}C$ under 1∼1,600 bars. The equilibrium constant of the complex was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift observed a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

• Journal of the Korean Chemical Society
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• v.8 no.1
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• pp.33-38
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• 1964

최근에 H.Eyring과 그의 공동연구자들은 "Significant liquid theory"를 제안하여 여러가지 액체에 대하여 잘 적용됨을 보여주고 있다$^{(3)-(12)}$. 그들은 고체와 액체 내부의 고체상 분자는 하나의 연속된 상을 이룬다고 보고 고체의 몰부피 $V_s$는 같다고 보았으나 Einstein특성온도 ${\theta}$나 승화열 $E_s$ 등은 서로 다른 값을 취하지 않으면 않되었을 뿐더러 가장 안정한 분자주위에 모여 올수 있는 자리수 n가 12보다 크게 되는 등의 실제적으로 생각하기 어려운 결과를 내놓았다. 그러나 우리는 고체상의 분자의 액체내부의 고체상분자와는 일반적으로 서로 다른 상태를 이루고 있으리라는 생각을 하여 액체가 존재하는 가장 낮은 온도 즉 삼중점을 액체의 기저상태로 보고 이점에서 parameter들을 정하였다. 이와같이 하여 정한 $V_s$는 고체의 경우보다 약간 크고 ${\theta}$나 $E_s$는 약간 작은 값이 나타나게 되었고 n도 12보다 작은 값이 나왔다. 이것은 실제적으로 매우 타당한 결과이며 또 이들을 써서 여러가지 열역학적인 양을 계산한 결과는 우리가 취급한 모든 물질들에 대해여 실측치와 좋은 일치를 보여주고 있다.