Letter
Engineering, Environmental
Xueyong Zhou, Xin Yu, Jianchao Hao, Huifen Liu
Summary: The calculation of equilibrium constant from the Langmuir model is widely used, but the dimensional problem of the equilibrium constant has often been overlooked. This comment analyzes the origin and background of this kind of error and presents a method for correcting it.
JOURNAL OF HAZARDOUS MATERIALS
(2022)
Article
Energy & Fuels
Zhenyu Shen, Yanjun Li, Nan Xu, Baozhi Sun, Wei Du, Min Xu, Lei Chang
Summary: The establishment of a combustion product equilibrium model is crucial for predicting NOx emissions from ships. Factors such as temperature, pressure, fuel-air equivalence ratio significantly affect the equilibrium mole fractions of combustion products.
Article
Thermodynamics
Henoc Flores, Fernando Ramos, Juan Rodriguez-Santiago, E. Adriana Camarillo
Summary: This study presents the estimation of vapor pressures of 3-formylchromone and 3-formyl-6-methylchromone using the isothermal thermogravimetry method. The method involves measuring the rate of mass loss with temperature in a cylindrical cell and nitrogen flow, and the Langmuir equation is used to derive the vapor pressure. The enthalpy, entropy, and Gibbs energy of sublimation were also calculated, and the validity of the method was tested with phenanthrene and pyrene vapor pressures.
THERMOCHIMICA ACTA
(2023)
Article
Chemistry, Physical
Chao-Wen Wang, Xiao-Long Peng, Jian-Yi Liu, Rui Jiang, Xiao-Ping Li, Yu-Song Liu, Shu-Yan Liu, Lin-Sheng Wei, Lie-Hui Zhang, Chun-Sheng Jia
Summary: A novel approach for representing the equilibrium constant of the water gas shift reaction (WGSR) is reported in this study, which only requires 3-6 molecular constants for each reactant and product as experimental data and does not involve fitting of any experimental equilibrium constant data. The reliability of the developed approach is demonstrated by comparing the predicted values with experimental data and other previous correlations, showing small average absolute deviations.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Green & Sustainable Science & Technology
A. Sangeetha, S. Shanmugan, Shiva Gorjian
Summary: This study investigates the potential of enhancing the productivity of a solar still by coating its sides with matte black paint mixed with activated carbon nanoparticles. The results show that this new design can increase the water temperature of the solar still, enhance its performance, and produce distilled water suitable for drinking.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Engineering, Chemical
Demetrios Chaconas, Patricia Pichardo, Ioannis Manousiouthakis, Vasilios Manousiouthakis
Summary: The Gibbs free energy minimization approach provides a general framework for thermodynamic equilibrium analysis of gas mixtures, allowing for simultaneous reaction and phase equilibrium studies. Two theorems ensure globally optimal equilibrium results, quantifying the equilibrium behavior under different temperature and pressure conditions.
Article
Engineering, Chemical
Walter W. Focke, Stefan Endres, Elizabeth L. du Toit, Mattheus T. Loots, Roelof L. J. Coetzer
Summary: A link was established between classic excess Gibbs free energy expressions and conventional mixture models, allowing the extension of the Margules and van Laar models to multicomponent mixtures. It was shown that the multicomponent form of the classic van Laar model features only one parameter per component in the mixture, and it is a special case of several other models. Various models like Porter, Margules, van Laar, NRTL, and Wilson are obtainable as special cases of the weighted double power mean mixture model.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Engineering, Chemical
S. B. Oyen, H. A. Jakobsen, T. Haug-Warberg, J. Solsvik
Summary: This work combines the concepts of chemical reaction equilibrium and transport phenomena, based on thermodynamic equilibrium rather than reaction kinetics, resulting in fewer model parameters. The model framework, exemplified by steam methane reforming and methanol synthesis processes, shows that orthogonal collocation is more efficient than finite volume, and Gibbs energy is more efficient than Helmholtz energy. The proposed model framework is a novel tool for calculating industrial reactors operating close to equilibrium, useful for process design studies but not accurate simulation.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Thermodynamics
S. Shanmugan, Joy Djuansjah, Mahmoud Ahmadein, Naser A. Alsaleh, Seyed Masoud Parsa, Ammar H. Elsheikh
Summary: Chemical potentials of the temperature components were evaluated to describe the behavior of water vapor and condensed water droplets in solar distillation using the pyramid stepped basin solar distiller. The study used the Gibbs phase rule to establish the relationship between design, climatic, and experimental parameters of the distiller. The internal heat transfer coefficients of the distiller were influenced by solar radiation intensity and ambient temperature, explaining the intensive state of the distiller. The research found a relation between the equilibrium of liquid and vapor mixture with temperature components of the distiller, and determined an efficiency of 38.135% with a distillate yield of 4.280 l/m2day over a 24 hour cycle.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Qingdong Miao, Ming Li, Baijun Yan
Summary: In this study, a method for determining the standard Gibbs energy of formation of Fe3-xVxO4 was proposed, and the standard Gibbs energies of formation of various Fe3-xVxO4 were experimentally determined. A computational model for the standard Gibbs energy of formation of Fe3-xVxO4 was also established.
Article
Engineering, Chemical
Allan M. M. Leal, William R. Smith
Summary: This study presents a mathematical framework for solving inverse chemical equilibrium problems, which involve unknown conditions in forward chemical equilibrium problems. It provides a method for determining the state of minimum Gibbs energy in a chemical system when some prescribed conditions are unknown.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Chemistry, Physical
Nuha Y. Owija, Samia A. Kosa, Mohamed Abdel Salam
Summary: Nano zero valent iron particles (NZVI) were synthesized using reduction method with sodium borohydride and ultrasonication, and were utilized for the removal of cadmium ions in aqueous solution. The thermodynamic study revealed a two-step removal process for cadmium ions by NZVI, with a possible presence of a third step. The reacted NZVI were characterized by various techniques, showing the formation of laminar residuals related to cadmium oxide and indicating a chemical irreversible process. A new method for calculating equilibrium constant in heterogeneous systems was explored, showing higher agreement with applied equations and independence from initial concentration variability, with validation against the Langmuir constant in adsorption process.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Analytical
Eric Ceballos-Alcantarilla, Antonio Abad-Fuentes, Consuelo Agullo, Antonio Abad-Somovilla, Josep Mercader
Summary: Immunoassays are widely used for rapid contaminant analysis in various samples, with the characterization of antibody-antigen interaction being crucial for developing sensitive tests. Competitive strategies are often employed for low molecular weight compounds to estimate apparent affinity values. In this study, monoclonal antibodies to penthiopyrad were successfully raised, with apparent equilibrium constants assessed using competitive enzyme-linked immunosorbent assays. The study showed close agreement between the obtained KD values and those calculated from surface plasmon resonance evaluation, and the developed immunoassay demonstrated good correlation with LC-MS/MS results.
Article
Chemistry, Physical
Kelei Zhuo
Summary: In this study, the relationship between Langmuir adsorption coefficients and Gibbs free energy change is derived in detail, and the applicable conditions for correct application and avoiding misuse are analyzed and discussed.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Green & Sustainable Science & Technology
Sakurako Wada, Takayuki Kushida, Haruna Itagaki, Toshimichi Shibue, Haruna Kadowaki, Jun Arakawa, Yukio Furukawa
Summary: The study determined the equilibrium constant K-ch values of carbamate hydrolysis reactions for both hindered amines and normal amines using a combination of C-13 NMR spectroscopy and chemical equilibrium analysis. The differences in properties between hindered amines and normal amines were revealed, with hindered amines showing negative Gibbs energy changes and normal amines showing positive changes. The obtained equilibrium constants and standard enthalpies will be useful for evaluating the performance of amine CO2 absorbents.
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
(2021)
