• Nuclear Engineering and Technology
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• 제53권2호
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• pp.611-617
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• 2021

The mechanical properties of α-Na₃(U_0.84(2),Na_0.16(2))O₄ have been researched using the first-principles calculations combined with the quasi-harmonic Debye model. The obtained lattice parameters agree well with the published experimental data. The results of elastic constants indicate that α-Na₃(U_0.84(2),Na_0.16(2))O₄ is mechanically stable. The polycrystalline moduli are predicted. The results show that the α-Na₃(U_0.84(2),Na_0.16(2))O₄ exhibits brittleness and possesses obvious elastic anisotropy. The hardness shows that it can be considered a "soft material". Furthermore, the Debye temperature θ_D and the minimum thermal conductivity k_min are also discussed, respectively. Finally, the thermal expansion coefficient α, isobaric heat capacity C_P and isochoric heat capacity C_V are evaluated through the quasi-harmonic Debye model.

• 방사성폐기물학회지
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• 제20권4호
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• pp.371-382
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• 2022

Carbonates are inorganic ligands that are abundant in natural groundwater. They strongly influence radionuclide mobility by forming strong complexes, thereby increasing solubility and reducing soil absorption rates. We characterized the spectroscopic properties of Am(III)-carbonate species using UV-Vis absorption and time-resolved laser-induced fluorescence spectroscopy. The deconvoluted absorption spectra of aqueous Am(CO₃)₂^- and Am(CO₃)₃^3- species were identified at red-shifted positions with lower molar absorption coefficients compared to the absorption spectrum of aqua Am³⁺. The luminescence spectrum of Am(CO₃)₃^3- was red-shifted from 688 nm for Am³⁺ to 695 nm with enhanced intensity and an extended lifetime. Colloidal Am(III)-carbonate compounds exhibited absorption at approximately 506 nm but had non-luminescent properties. Slow formation of colloidal particles was monitored based on the absorption spectral changes over the sample aging time. The experimental results showed that the solubility of Am(III) in carbonate solutions was higher than the predicted values from the thermodynamic constants in OECD-NEA reviews. These results emphasize the importance of kinetic parameters as well as thermodynamic constants to predict radionuclide migration. The identified spectroscopic properties of Am(III)-carbonate species enable monitoring time-dependent species evolution in addition to determining the thermodynamics of Am(III) in carbonate systems.

• 한국항해항만학회지
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• 제48권2호
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• pp.125-136
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• 2024

This research presents an innovative integrated ethanol solid oxide fuel cell (SOFC) system designed for applications in marine vessels. The system incorporates an exhaust gas heat recovery mechanism. The high-temperature exhaust gas produced by the SOFC is efficiently recovered through a sequential process involving a gas turbine (GT), a regenerative system, steam Rankine cycles, and a waste heat boiler (WHB). A comprehensive thermodynamic analysis of this integrated SOFC-GT-SRC-WHB system was performed. A simulation of this proposed system was conducted using Aspen Hysys V12.1, and a genetic algorithm was employed to optimize the system parameters. Thermodynamic equations based on the first and second laws of thermodynamics were utilized to assess the system's performance. Additionally, the exergy destruction within the crucial system components was examined. The system is projected to achieve an energy efficiency of 58.44% and an exergy efficiency of 29.43%. Notably, the integrated high-temperature exhaust gas recovery systems contribute significantly, generating 1129.1 kW, which accounts for 22.9% of the total power generated. Furthermore, the waste heat boiler was designed to produce 900.8 kg/h of superheated vapor at 170 ℃ and 405 kP a, serving various onboard ship purposes, such as heating fuel oil and accommodations for seafarers and equipment.

• 공업화학
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• 제18권3호
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• pp.267-272
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• 2007

$25^{\circ}C$의 순수 물 및 n-부탄올 수용액(0.1 M, 0.2 M 및 0.3 M)에서 양이온 계면활성제인 trimethyltetradecylammonium bromide (TTAB)와 비이온 계면활성제인 polyoxyethylene (23) lauryl ether (Brij 35)의 혼합계면활성제의 임계미셀농도 (CMC)와 반대이온의 결합상수값(B)을 TTAB의 겉보기 몰분율(${\alpha}_1$)의 함수로서 전도도법과 표면장력계법으로 측정하였다. 이와 같이 측정한 CMC 값에 비이상적 혼합미셀화 모델을 적용함으로써 여러 가지 열역학적 함수값($X_i$, ${\gamma}_i$, $C_i$, ${a_i}^M$, ${\beta}$ 및 ${\Delta}H_{mix}$)들을 계산하고 분석하였다. 또한 TTAB/Brij 35 혼합계면활성제의 미셀화에 미치는 n-부탄올의 농도에 따른 열역학 함수값들의 변화를 측정하고 분석하였다.

• 대한화학회지
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• 제50권5호
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• pp.355-361
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• 2006

순수 물 및 n-부탄올 수용액(0.1M, 0.2M, 0.3M)에서 음이온 계면활성제인 sodium dodecyl benzenesulfonate(DBS)와 비이온 계면활성제인 dodecyl polyoxyethylene(23) lauryl ether(Brij 35)의 혼합계면활성제의 임계미셀농도(CMC)와 반대이온의 결합상수값(B)을 DBS의 겉보기 몰분율(1)의 함수로서 전도도법과 표면장력계법으로 측정하였다. 이와 같이 측정한 CMC값에 비이상적 혼합미셀화모델을 적용함으로써 여러 가지 열역학적 함수값(Xi, i, Ci, aiM, 및 Hmix)들을 계산하고 분석하였다. 그리고 DBS/Brij 35 혼합계면활성제의 미셀화에 미치는 n-부탄올의 농도에 따른 열역학 함수값들의 변화를 측정하고 분석하였다.

• 대한화학회지
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• 제41권1호
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• pp.12-17
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• 1997

순수 물 및 n-부탄올 수용액에서 Sodium dodecylsulfate(SDS)와 Sodium dodecylbenzenesulfonate(DBS)의 혼합계면활성제가 나타나는 임계미셀농도(CMC*) 및 반대이온들의 결합상수값(B)을 25℃에서 전도도법으로 측정하였다. 이들 CMC* 및 B값들의 α1(SDS의 전체 몰분율조성)에 따른 변화로부터 비이상적 혼합 미셀모델을 적용함으로써 여러가지 열역학적 함수값들(Xi, γi, Ci, aiM, β, ΔHmix 및 ΔGm0)을 계산하였으며, 또한 SDS/DBS혼합계면활성제의 미셀화에 미치는 n-부탄올의 효과를 조사하기 위하여 n-부탄올의 농도(0.1 M, 0.2 M 및 0.3 M)에 따른 이들 열역학함수값들의 변화를 측정하여 순수 물에서의 값들과 서로 비교함으로써 분석하였다.

• Membrane and Water Treatment
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• 제8권3호
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• pp.259-277
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• 2017

Adsorption is a widely used technique for the removal of dyes from wastewaters by variety of adsorbents. In this work, the main focus is on the potential assessment of anion exchange membrane for the removal of different dyes using batch system and investigation of experimental data by applying various kinetic and thermodynamic models. The removal of anionic dyes i.e., Eosin-B, Eriochrome Black-T and Congo Red by anion exchange membrane BII from aqueous solution was carried out and effect of various parameters such as contact time, membrane dosage, temperature and ionic strength on the percentage removal of anionic dyes was studied. The experimental data was assessed by kinetic models namely pseudo-first-order, pseudo-second-order, Elovich liquid film diffusion, Bangham and the modified Freundlich models equation have been used to analyze the experimental data. These results indicate that the adsorption of these anionic dyes on BII follows pseudo-second-order kinetics with maximum values of regression coefficient (0.992-0.998) for all the systems. The adsorption of dyes was more suitable to be controlled by a liquid film diffusion mechanism. The adsorptive removal of dye Eosin-B and Eriochrome Black-T were decreased with temperature and thermodynamic parameters such as free energy (${\Delta}G^o$), enthalpy (${\Delta}H^o$) and entropy (${\Delta}S^o$) for adsorption of dyes on membrane BII were calculated at 298 K, 308 K and 318 K. The values of enthalpy and entropy were negative for EB and EBT representing that the adsorption of these dyes on BII is physiosorptive and exothermic in nature. Whereas the positive values of enthalpy and entropy for CR adsorption on BII, indicating that its adsorption is endothermic and spontaneous in nature. It is evident from this study that anion exchange membrane has shown good potential for the removal of dyes from aqueous solution and it can be used as adsorbent for dues removal on commercial levels.

• Korean Chemical Engineering Research
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• 제54권6호
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• pp.734-745
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• 2016

This review article described the electrochemical Frumkin, Langmuir, and Temkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) and deuterium (OPD D) for the cathodic $H_2$ and $D_2$ evolution reactions (HER, DER) at Pt, Ir, Pt-Ir alloy, Pd, Au, and Re/normal ($H_2O$) and heavy water ($D_2O$) solution interfaces. The Frumkin, Langmuir, and Temkin adsorption isotherms of intermediates (OPD H, OPD D, etc.) for sequential reactions (HER, DER, etc.) at electrode/solution interfaces are determined using the phase-shift method and correlation constants, which have been suggested and developed by Chun et al. The basic procedure of the phase-shift method, the Frumkin, Langmuir, and Temkin adsorption isotherms of OPD H and OPD D and related electrode kinetic and thermodynamic parameters, i.e., the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. potential (E) behavior (${\theta}$ vs. E), equilibrium constant (K), interaction parameter (g), standard Gibbs energy (${\Delta}G_{\theta}{^{\circ}}$) of adsorption, and rate (r) of change of ${\Delta}G_{\theta}{^{\circ}}$ with ${\theta}$ ($0{\leq}{\theta}{\leq}1$), at the interfaces are briefly interpreted and summarized. The phase-shift method and correlation constants are useful and effective techniques to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and related electrode kinetic and thermodynamic parameters (${\theta}$ vs. E, K, g, ${\Delta}G_{\theta}{^{\circ}}$, r) at electrode/solution interfaces.

• 대한화학회지
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• 제38권5호
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• pp.345-350
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• 1994

클로로포름과 사염화탄소 속에서 티오아세트아미드(TA)와 pyridine(Py), quinoline(Qu), and acridine(Ac)간의 수소 결합에 대한 열역학적 상수들을 조사하기 위해 5$^{\circ}C$ 에서 55$^{\circ}C$까지 TA의 $v_{a^+}$ Amide II조합띠를 사용하였다. 이 조합띠는 두 개의 Lorentzian-Gauss 곱함수의 띠로 분해되며, 각각은 TA단위체 및 수소결합을 이룬 TA의 복합체임이 확인되었다. 온도 및 농도에 따른 이 조합띠의 변화로부터 TA의 수소 결합에 대한 여러가지 열역학적 상수들을 구하였다. 클로로포름에서 TA 와 pyridine, quinoline, acridine의 수소결합 엔탈피는 각각 -7.6 kJ/mol, -6.5 kJ/mol, -5.4 kJ/mol이었고, 사염화탄소에서 TA 와 pyridine, quinoline의 결합 엔탈피는 각각 -13.3kJ/mol, -12.0kJ/mol이었다.

• 대한화학회지
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• 제48권3호
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• pp.236-242
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• 2004

25$^{\circ}C$의 순수 물 및 n-부탄올 수용액에서 Dodecylpyridinium chloride(DPC)와 Cetyldimethylethylammonium bromide(CDEAB)의 혼합계면활성제가 나타내는 임계마이셀농도(CMC)와 반대이온결합상수(B)값을 DPC의 겉보기몰분율(${\alpha}_1$)에 따른 변화를 전도도법으로 측정하였다. 이와같이 측정한 CMC값에 비이상적 혼합마이셀화모델을 적용함으로써 여러 가지 열역학적 함수값(($X_i,\;{\gamma}_i,\;C_i,\;a^M_i,\;{\beta},\;and\;{\Delta}H_{mix})$들을 계산하고 분석하였다. 그리고 DPC/CDEAB 혼합계면활성제의 마이셀화에 미치는 n-부탄올의 효과를 조사하기 위하여 n-부탄올의 농도에 따른 열역학 함수값(CMC, B 및 ${\Delta}G_o\;^m$)의 변화를 측정하고 분석하였다.