Nonrandom Lattice Fluid Model Research Articles

A crossover quasi-chemical nonrandom lattice fluid model for pure carbon dioxide and hydrocarbons

Thequasi-chemical nonrandom lattice fluid model is capable of describing thermodynamic properties for complex systems containing associating fluids, polymer, biomolecules and surfactants, but this model fails to reproduce the singular behavior of fluids in the critical region. In this research, we used the quasi-chemical nonrandom lattice fluid model and combined this model with a crossover theory to obtain a crossover quasi-chemical nonrandom lattice fluid model which incorporated the critical scaling laws valid asymptotically close to the critical point and reduced to the original quasi-chemical nonrandom model far from the critical point. The crossover quasi-chemical nonrandom lattice fluid model showed a great improvement in prediction of the volumetric properties and second-order derivative properties near the critical region.

Solubility of hinokitiol in supercritical fluids; measurement and correlation

Supercritical fluid technology has been an alternative for purification and separation of biological compounds in cosmetic, food, and pharmaceutical products. Solubility information of biological compounds in supercritical fluids is essential for choosing a supercritical fluid processes. The equilibrium solubility of hinokitiol was measured in supercritical carbon dioxide and ethane with a static method in the pressure range from 8 to 40MPa and at temperatures equal to 313.2, 323.2 and 333.2 K. The experimental data were correlated well by Peng-Robinson equation of state and quasi-chemical nonrandom lattice fluid model.

A crossover multi-fluid nonrandom lattice fluid model for pure hydrocarbons and carbon dioxide near to and far from the critical region

The multi-fluid nonrandom lattice fluid model with the local composition concept is capable of describing thermodynamic properties for complex systems, but this model cannot represent the singular behavior of fluids near the critical region. In this research, the multi-fluid nonrandom lattice fluid model for pure fluids is combined with a crossover theory to obtain a crossover multi-fluid nonrandom lattice fluid model which incorporates the critical scaling laws valid asymptotically close to the critical point and reduces to the original classical multi-fluid nonrandom model far from the critical point. The crossover multi-fluid nonrandom lattice fluid model shows a great improvement in prediction of the thermodynamic properties of pure compounds near the critical region.

계면활성제를 함유한 혼합물에서 내외부 분자회합을 위한 격자모델

분자내부 회합은 계면활성제계, 특히 콜로이드와 생체물질에 있어서 수소결합 중에서 매우 중요한 역할을 나타낸다. 미셀과 마이크로에멀젼을 형성하는 양친매성 계는 분자간 회합뿐만 아니라 분자내부 회합 때문에 매우 비이상적인 거동을 나타낸다. 본 연구의 목적은 계면활성제를 함유한 혼합물의 상거동을 계산하기 위하여, 내외부 분자 회합을 설명할 수 있는 수정된 베이츠만 통계역학이론과 결합된 유사화학반응 비무질도서 격자모델을 제시하는 것이다. 본 논문에서 제시된 격자모델은 알칸과 계면활성제의 실험결과를 매우 잘 설명할 수 있다. Intra-molecular association is an important contribution to the overall hydrogen bonding in surfactant systems, especially in systems of colloidal and biological interest. Amphiphile systems, especially micelle and microemulsion systems, showed highly non-ideal behavior due to the intermolecular association and intra-molecular association. The objective of this research is to present a lattice fluid equation of state that combines the quasi-chemical nonrandom lattice fluid model with modified Veytsman statistics for intra + inter molecular association to calculate phase behavior for mixture containing surfactant systems. The lattice model could describe the literature data well for alkane and surfactant systems.

Modified Guggenheim-Huggins-Miller combinatorial factor and its application to lattice fluid equation of state

The Guggenheim-Huggins-Miller (GHM) combinatorial factor is modified by introducing a factor in the pair probability of a hole-hole pair. The proposed contribution is combined with the expanded quasi-chemical contribution and tested against saturated vapor pressure and liquid density. The proposed model correlates experimental saturated liquid density better than a quasi-chemical nonrandom lattice fluid (QLF) model based on original GHM combinatorial factor. The optimized parameters show a quite different behavior compared with that of the QLF model and the relationships between the parameters of two models are discussed.

A multi-fluid nonrandom lattice fluid model for mixtures containing nonionic surfactants

Surfactant systems show highly non-ideal phase behavior because of the inter-association and intra-association hydrogen bond. We present a lattice fluid equation of state that combines the multi-fluid nonrandom lattice fluid model with modified Veytsman statistics for intra+inter molecular association to calculate phase behavior for mixture containing surfactant systems. The literatureresults fitted to this model show good accordance for mixtures containing nonionic surfactant systems.

Solubility of climbazole and triclocarban in supercritical carbon dioxide: Measurement and correlation

The supercritical technology has been considered as an appropriate alternative for separation of biomaterials from cosmetic, food, and pharmaceutical products. The solid solubility of biological compounds is the most important thermodynamic parameter in the supercritical extraction and purification. The equilibrium solubility of two biocides, climbazole, and triclocarban was measured in supercritical carbon dioxide with static method in the pressure range from (10 to 40) MPa and at temperatures equal to (313.2, 323.2, and 333.2) K. The experimental data were correlated by Peng–Robinson equation of state and quasi-chemical nonrandom lattice fluid model.

Measurement and correlation of (vapor + liquid) equilibria for the {2-propoxyethanol (C 3E 1) + n-hexane} and the {2-propoxyethanol (C 3E 1) + n-heptane} systems

2-Propoxyethanol (C 3E 1) is one of nonionic surfactants which are a particularly interesting class of substances due to both inter-molecular and intra-molecular association. Binary (vapor + liquid) equilibrium data were measured for {2-propoxyethanol (C 3E 1) + n-hexane} and {2-propoxyethanol (C 3E 1) + n-heptane} systems at temperatures ranging from (303.15 to 323.15) K. A static apparatus was used in this study. The experimental data were correlated well with a lattice fluid equation of state that combines the multi-fluid non-random lattice fluid model with Veytsman statistics for (intra + inter)-molecular association.

Solubility of iodopropynyl butylcarbamate in supercritical carbon dioxide

Supercritical carbon dioxide has been considered an appropriate alternative for extraction and purification process of cosmetics, pharmaceuticals, food supplements and natural products. Solubility information of biological compounds is essential for choosing supercritical fluid (SCF) processes. The solubility of iodopropynyl butylcarbamate (IPBC), a fungicide and anti-dandruff agent, was measured in supercritical carbon dioxide with a high pressure apparatus equipped with a variable volume view cell at 313.15, 323.15, and 333.15 K and at pressure between 80 and 35 MPa. The experimental data were correlated well with Peng–Robinson equation of state (PR EOS) and quasi-chemical nonrandom lattice fluid model.

Phase equilibria for mixtures containing nonionic surfactant systems: Modeling and experiments

Surfactants are important materials with numerous applications in the cosmetic, pharmaceutical, and food industries due to inter-associating and intra-associating bond. We present a lattice fluid equation-of-state that combines the quasi-chemical nonrandom lattice fluid model with Veytsman statistics for (intra + inter) molecular association to calculate phase behavior for mixtures containing nonionic surfactants. We also measured binary (vapor + liquid) equilibrium data for {2-butoxyethanol (C 4E 1) + n-hexane} and {2-butoxyethanol (C 4E 1) + n-heptane} systems at temperatures ranging from (303.15 to 323.15) K. A static apparatus was used in this study. The presented equation-of-state correlated well with the measured and published data for mixtures containing nonionic surfactant systems.

An Electrolyte Equation of State Based on a Hydrogen-Bonding Nonrandom Lattice Fluid Model for Concentrated Electrolyte Solutions

Equations of state that are based on lattice fluids have been in use for nonelectrolyte components and their mixtures with somewhat different characteristics from hard-sphere chain-based equations of state or cubic equations. In the present study, an electrolyte equation of state was developed, based on a hydrogen-bonding nonrandom lattice fluid theory, by adding the long-range contribution that is due to the mean spherical approximation. Hydrogen bonding of solvent molecules and solvation between solvent molecules and cations were explicitly included by association contribution to extend the applicability to highly concentrated electrolyte solutions. Segment numbers of ions were obtained from the Pauling diameter, using the previously developed relationship between lattice and off-lattice fluids. The remaining electrolyte parameters—namely, interaction energy between electrolyte and solvent, hydrated ionic diameter, and hydration energy between cation and solvent molecule—were fitted to osmotic coefficie...

A quasi-chemical nonrandom lattice fluid model for phase equilibria of associating systems

The contribution from Veytsman statistics for associating is combined with the quasi-chemical nonrandom lattice fluid (QLF) equation of state developed by the present authors. The physical contribution is characterized by temperature independent molecular parameters, representing close packed volume of a mer, segment numbers and energy parameters of a pure fluid, and a binary interaction parameter for a mixture. The chemical part is represented by the internal energy and entropy of the associating system. The resulting quasi-chemical nonrandom associating lattice fluid equation of state was applied to describe thermodynamic properties of pure fluids and phase equilibria of mixtures. The absolute chemical potentials which are derived from the canonical partition function are presented by using the fundament thermodynamic relations to consistently calculate phase equilibrium properties. The results for alkane–alkanol and alcohol–alkanol mixtures were found satisfactory for most systems when compared with the quasi-chemical nonrandom lattice fluid model and the statistical associating fluid theory model.

A quasi-chemical nonrandom lattice fluid model: General derivation and application to pure fluids and mixtures

A quasi-chemical nonrandom lattice fluid model without temperature dependence of the close packed volumes of a mer, segment numbers and energy parameters of pure systems is presented. The explicit nonrandom lattice fluid (NLF) model with quasi-chemical approach was capable of describing properties for complex systems, but this model had strong the temperature dependence of energy parameters and segment numbers of pure systems. In this work, a quasi-chemical nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems is proposed. And the model was extended to mixtures by using consistent method for phase equilibrium calculation with fugacity coefficients derived from the present equation of state. We tested consistently the present model on 17 phase equilibrium data sets of vapor–liquid equilibria and compared with the NLF model and the SAFT model. The present model (three pure parameters for pure component and one binary interaction parameter) showed better results for most systems than the NLF model (six adjustable pure parameters and one binary interaction parameter) and the SAFT model (three pure parameters and one binary interaction parameter).

A multi-fluid nonrandom lattice fluid model: General derivation and application to pure fluids

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems is presented. The multi-fluid nonrandom lattice fluid (MF-NLF) model with the local composition concept was capable of describing properties for complex systems. However, the MF-NLF model has strong temperature dependence of energy parameters and segment numbers of pure systems; thus empirical correlations as functions of temperature were represented for reliable and convenient use in engineering practices. The MF-NLF model without temperature dependence of pure parameters could not predict thermodynamic properties accurately. It was found that the present model with three parameters describes quantitatively the vapor pressure and the saturated density for the pure fluid.

A multi-fluid nonrandom lattice fluid model: Mixtures

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems and its consistent method for phase equilibrium calculation were presented in the previous paper. In this work, the model was extended to mixtures by using consistent method for phase equilibrium calculation with fugacity coefficients derived from the present equation of state and it was applied to vapor-liquid equilibrium. We consistently tested the present model on 17 phase equilibrium data sets of vapor-liquid equilibria and compared it with the MF-NLF model and the SAFT model. The present model (3 pure parameters for pure component and one binary interaction parameter) showed better results for most systems than the MF-NLF model (6 adjustable pure parameters and one binary interaction parameter) and the SAFT model (3 pure parameters and one binary interaction parameter).

Simultaneous description of excess properties and vapor–liquid equilibria for associating mixtures by hydrogen-bonding lattice fluid equation of state

Since all residual thermodynamic properties can be calculated from an equation of state (EOS), an accurate EOS may also be used for the computation of excess properties and vapor–liquid equilibria (VLE) simultaneously. Cubic equations of state have been used with G E-mixing rules for associating mixtures. In the present study, the applicability of the hydrogen-bonding non-random lattice fluid model (NLF-HB) was investigated for the simultaneous correlation of VLE and excess properties of mixtures containing associating components. The optimized parameters for VLE and H E at room temperature gave reliable results for fitted properties. V E calculation showed large errors but the molar volume was accurate. The allowable range for the temperature extrapolation of the binary parameter was wider for VLE than for for H E.

Extended hydrogen-bonding lattice fluid theory for dimers and n-mers

The importance of contributions to real fluid properties by specific interactions has long been recognized. However, it is only recent since such effects have been incorporated into an equation of state. Still the description of some associating systems including organic acids presented difficulties. To explore the solution for such systems, the Veytsman’s statistics was extended for dimers and n-mers. Combining the extended statistics with the physical contribution of the present authors’ nonrandom lattice fluid model a new Helmholtz’s free energy equation was proposed and the resulting equations for pressure and chemical potential were derived. Vapor–liquid equilibria for binary mixtures of organic acids, alcohol, water and alkanes were calculated using the model. The results were found satisfactory for most systems when compared with experimental data.

An explicit hydrogen-bonding non-random lattice–fluid equation of state and its applications

The representation of hydrogen-bonding contribution by Huang and Radosz or by Veytsman involves terms that require implicit computation when more than one type of bonds is present. To reduce the computational burden associated with the solution of a set of nonlinear implicit equations, a free energy expansion method was proposed for Veytsman statistics in the present study. Based on the normalized Veytsman statistics, the Helmholtz free energy for association was expanded around a reference value. The expanded free energy was compared with rigorous values and found to closely approximate the original term. The lattice-compatible expanded Veytsman term was then combined with the explicit non-random lattice–fluid model of present authors to give the explicit free energy expression for hydrogen-bonding non-random lattice–fluid. Parameters for the model are segment number and interaction energy for physical interaction, and association enthalpy and entropy for hydrogen bonding. For a binary mixture, a binary parameter is needed. To assure the consistency, thermodynamic properties such as pressure and chemical potential were derived from the expanded Helmholtz free energy. Calculated vapor–liquid equilibria using the expansion for alkane–alkanol mixtures were found to closely agree with experimental values and with rigorous calculation results.

A nonrandom lattice fluid hydrogen bonding theory for phase equilibria of associating systems

The Veytsman statistics for hydrogen bonding (HB) contribution is combined with the nonrandom lattice fluid (NLF) model developed recently by the present authors. The physical contribution is characterized by two temperature dependent molecular parameters representing molecular size and interaction energy for a pure fluid, and a binary interaction parameter for a binary mixture. The chemical part is represented by internal energy and entropy of HB. The resulting NLF-HB equation of state was applied to describe thermodynamic properties of pure fluids and phase equilibrium of mixtures. The results for alkane–alcohol mixtures showed significant improvements over those of the NLF EOS (equation of state) and HM (hole quasichemical group-contribution) model.

A new equation of state based on nonrandom two-fluid lattice theory for complex mixtures

A new simplified equation of state (EOS) was derived based on the nonrandom lattice fluid model with the introduction of the two-fluid theory. Admittedly the new EOS was originated from the density dependent combinatory and has features similar to the UNIQUAC model. However, it results in volumetric EOS instead of excess Gibbs energy model. The new EOS was tested for its capacity to represent the phase equilibrium behaviors of pure components and mixtures. The model was applied to density, equilibria of vapor-liquid and vapor-solid phases for nonpolar/nonpolar, nonpolar/polar, and polar/polar binary mixtures of simple and complex molecules. The simplified EOS was successfully applied to the activities of solvents in polymer solutions. With two parameters for pure components and one binary interaction energy parameters, results obtained to date demonstrate that the model is quantitatively applicable to a wide range of temperatures, pressures and densities.