scholarly journals Mass action model of solution activity via speciation by solvation and ion pairing equilibria

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Aaron D. Wilson ◽  
Hyeonseok Lee ◽  
Caleb Stetson
Keyword(s):  
Dissociation Constant ◽  
Ion Pairing ◽  
Mass Action ◽  
Solution Model ◽  
Dominant Factor ◽  
Ion Dissociation ◽  
Solution Processes ◽  
Solution Models ◽  
Action Model ◽  
Equilibrium Data

AbstractSolutes and their concentrations influence many natural and anthropogenic solution processes. Electrolyte and solution models are used to quantify and predict such behavior. Here we present a mechanistic solution model based on mass action equilibria. Solvation and ion pairing are used to model speciated solute and solvent concentrations such that they correlate to a solution’s vapor pressure (solvent activity) according to Raoult’s law from dilute conditions to saturation. This model introduces a hydration equilibrium constant (Kha) that is used with either an ion dissociation constant (Kid) or a hydration modifier (m) with an experimentally determined ion dissociation constant, as adjustable parameters to fit vapor–liquid equilibrium data. The modeled solvation equilibria are accompanied by molecular dynamics (MD) studies that support a decline in the observed degree of solvation with increased concentration. MD calculations indicate this finding is a combination of a solvent that solvates multiple solutes, and changes in a solute’s solvation sphere, with the dominant factor changing with concentration. This speciation-based solution model is lateral to established electrostatics-based electrolyte theories. With its basis in mass action, the model can directly relate experimental data to the modeled solute and solvent speciated concentrations and structures.

Liquid-liquid equilibria of butyric acid for solvents containing a phosphonium ionic liquid

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Ján Marták ◽  
Štefan Schlosser
Keyword(s):  
Ionic Liquid ◽  
Butyric Acid ◽  
Distribution Coefficients ◽  
Mass Action ◽  
A Value ◽  
Mass Action Model ◽  
Phosphonium Ionic Liquid ◽  
Action Model ◽  
Equilibrium Data ◽  
Cyphos Il 104

AbstractL/L equilibrium data of butyric acid (BA) in aqueous solutions contacted with the solvents containing ionic liquid (IL), trihexyl-(tetradecyl)phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL-104), and a related model are presented. IL-104 and its solutions in dodecane were found to be effective solvents of BA. The values of the distribution coefficients of BA were higher than those for solvents with the widely used extractant trioctylamine, especially at low acid concentrations and were also several-fold higher than those of lactic acid (LA). IL extracted BA only in its undissociated form (BAH) at pH well below pK a of the acid. The loading of IL was independent of IL concentration and it achieved a value higher than four at saturation. Complexes with 1–5 molecules of BA per one IL molecule were supposed in the mass action model in which the reactive formation of complexes (BAH)p(IL)(H2O)2 was supposed. Up to 10 % of the total extracted BA was extracted physically by dodecane as a monomer and dimer, in the solvent. The water content in the organic phase steeply decreased with the BA concentration, which was caused by splitting water-IL reverse micelles due to the formation of the BAH/IL complexes.

Modelling and Experimental Studies of Sorption in the Near Field of a Cementitious Repository

1989 ◽  
Vol 176 ◽  
Author(s):  
P.L. Brown ◽  
A. Haworth ◽  
R. McCrohon ◽  
S.M. Sharland ◽  
C.J. Tweed
Keyword(s):  
Near Field ◽  
Experimental Studies ◽  
Mass Action ◽  
Chemical Equilibria ◽  
Transport Code ◽  
Mass Action Model ◽  
Action Model ◽  
Modelling Studies ◽  
Simple Mass

ABSTRACTA joint experimental and modelling programme is reported, which aims to improve our understanding of sorption processes of radionuclides onto repository materials. Diffusion/sorption experiments of sorption onto cement are described, although results are limited at this stage. The modelling studies use the coupled chemical equilibria and transport code CHEQMATE to simulate some of these experiments. The chemical part of the model is based on a simple mass-action model of sorption. More detailed comparisons will continue when the experiments are terminated, and the samples are sectioned.

Inferring gene regulatory networks using a time-delayed mass action model

2016 ◽  
Vol 14 (04) ◽  
pp. 1650012
Author(s):  
Yaou Zhao ◽  
Mingyan Jiang ◽  
Yuehui Chen
Keyword(s):  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Classical Model ◽  
Population Based ◽  
Mass Action ◽  
Mass Action Model ◽  
Action Model ◽  
Gene Regulatory ◽  
Efficient Learning ◽  
Delay Differential

This paper demonstrates a new time-delayed mass action model which applies a set of delay differential equations (DDEs) to represent the dynamics of gene regulatory networks (GRNs). The mass action model is a classical model which is often used to describe the kinetics of biochemical processes, so it is fit for GRN modeling. The ability to incorporate time-delayed parameters in this model enables different time delays of interaction between genes. Moreover, an efficient learning method which employs population-based incremental learning (PBIL) algorithm and trigonometric differential evolution (TDE) algorithm TDE is proposed to automatically evolve the structure of the network and infer the optimal parameters from observed time-series gene expression data. Experiments on three well-known motifs of GRN and a real budding yeast cell cycle network show that the proposal can not only successfully infer the network structure and parameters but also has a strong anti-noise ability. Compared with other works, this method also has a great improvement in performances.

Which value for the first dissociation constant of carbonic acid should be used in biological work?

1991 ◽  
Vol 260 (5) ◽  
pp. C1113-C1116 ◽  
Author(s):  
R. W. Putnam ◽  
A. Roos
Keyword(s):  
Ionic Strength ◽  
Activity Coefficient ◽  
Dissociation Constant ◽  
Carbonic Acid ◽  
Mass Action ◽  
Bicarbonate Concentration ◽  
Apparent Dissociation Constant ◽  
Logarithmic Form ◽  
Ion Activity ◽  
Hasselbalch Equation

The apparent first dissociation constant of carbonic acid has been defined in different ways in the literature. Harned and co-workers (8-10) have defined it in terms of molalities of the participating species, including H ions: Ks = mHmHCO3/mCO2. In contrast, Hastings and Sendroy have defined an apparent constant in which acidity is expressed as H ion activity: K'1 = aHmHCO3/mCO2. These constants differ by a factor gamma H, the activity coefficient of H ions at the prevailing ionic strength. Therefore, pK'1 is greater than pKs by an amount equal to -log gamma H, which, at mu = 0.16 M, is approximately 0.1. It is important that the correct value for the apparent dissociation constant or its logarithmic form be entered in the mass action expression or in the Henderson-Hasselbalch equation in order to prevent significant errors in the computation by means of these equations of quantities that cannot be directly measured. Specifically, for the derivation of bicarbonate concentration from PCO2 and pH (-log aH), pK'1 is to be used and not an uncorrected pKs.

Optimal determination of steric mass action model parameters for β-lactoglobulin using static batch experiments

2010 ◽  
Vol 1217 (26) ◽  
pp. 4267-4277 ◽  
Author(s):  
Tilman Barz ◽  
Verena Löffler ◽  
Harvey Arellano-Garcia ◽  
Günter Wozny
Keyword(s):  
Mass Action ◽  
Model Parameters ◽  
Batch Experiments ◽  
Mass Action Model ◽  
Action Model ◽  
Β Lactoglobulin

Thermodynamics of micellization and solubilization in systems of water – sodium n-alkylcarboxylates – alkoxyethanols at 25 °C

1997 ◽  
Vol 75 (11) ◽  
pp. 1445-1462 ◽  
Author(s):  
H. Huang ◽  
R.E. Verrall
Keyword(s):  
Aqueous Solutions ◽  
Distribution Coefficient ◽  
Chain Length ◽  
Transfer Functions ◽  
Mass Action ◽  
Sodium Carboxylate ◽  
Medium Chain Length ◽  
Head Groups ◽  
Action Model ◽  
State Formula

The apparent molar volumes and adiabatic compressibilities, [Formula: see text] of carboxylate surfactants, CnNa (n = 8, 10, 12), in aqueous solutions in the absence and presence of medium-chain-length alkoxyethanols, C4EOX (EO = ethylene oxide group, X = 0–4), and of alkoxyethanols, [Formula: see text] in aqueous solutions in the absence and presence of surfactant, were determined at 25 °C from density and sound velocity measurements as a function of both the surfactant and alcohol concentrations. The partial molar volumetric properties of CnNa and the transfer functions of C4EOX from water to aqueous surfactant solutions were calculated from the apparent molar properties. Values of the thermodynamic parameters of micellization for CnNa, i.e., the critical micelle concentration, the partial molar property of the monomer at infinite dilution, [Formula: see text] and in the micellar state, [Formula: see text] were obtained from simulations of the experimental data, [Formula: see text] using a mass-action model. As expected, these properties are strongly dependent on the surfactant chain length. The distribution coefficient of C4EOX between the micelle and aqueous phases, KD, and the change in the molar property of alcohols due to micellization, [Formula: see text] extracted from fitting the transfer function data of C4EOX using a chemical equilibrium model, show that the solubilization of alkoxyethanols in carboxylate micelles is enhanced by increasing the surfactant chain length and the number of EO groups in the alcohol. The deeper penetration of C4EOX into the micelles of longer chain surfactants is associated with increasingly stronger interactions between surfactant head groups and EO segments of the alcohol on (or near) the micelle surface. Aggregation numbers of CnNa–C4EOX mixed micelles show that addition of a small amount of C4EOX has little effect on the structure of the micelles formed from C8Na and C10Na, but leads to significant change in C12Na micelles. Keywords: sodium carboxylate salts, alkoxyethanols, partial molar volume and compressibility, transfer functions, distribution coefficient, mean aggregation number.

Cation Exchange in Porous Media With Broad-Equivalent-Weight Sulfonate Micellar Fluids

1985 ◽  
Vol 25 (04) ◽  
pp. 580-586 ◽  
Author(s):  
A.F. Chan ◽  
V.J. Kremesec
Keyword(s):  
Porous Media ◽  
Cation Exchange ◽  
Single Phase ◽  
Divalent Cations ◽  
Mass Action ◽  
Micellar System ◽  
Mass Action Model ◽  
Action Model ◽  
Parameter Values ◽  
Micellar Fluids

Abstract This paper describes experimental and theoretical studies of cation exchange in porous media with micellar fluids formulated using a broad-equivalent-weight (BEW) sulfonate. The sulfonates can be described as composed of two pseudocomponents a quasi-monosulfonate (the oil-moving pseudo components a quasi-monosulfonate (the oil-moving component) and a quasi-disulfonate (the sulfonate-solubilizing component). With this description and a mass-action model for cation exchange between the micelles, clays, and solution, a match between computer model predictions and results of laboratory single-phase flow tests in Berea sandstone was carried out. The assumptions required are reviewed and independent experimental results presented. With these assumptions and parameter values determined from the Berea history match, satisfactory predictions of divalent cation concentrations in field core experiments have been made. The good predictive capability of this model allows initial screening and development of micellar formulations for specific reservoir applications to be conducted at appropriate hardness levels. Introduction It is well known that the oil recovery performance of a micellar fluid is strongly affected by salinity and hardness (calcium and magnesium divalent cations). This is because they have strong effects on the phase behavior and interfacial tension (IFT) of the surfactant/oil/brine system. It is also well known that the hardness and salinity of the micellar fluid can change significantly as a result of cation exchange and dissolution as the micellar fluid propagates through the reservoir. Since a knowledge of the in-situ levels of salinity and hardness is of primary importance in the screening and development of micellar fluids for field applications, an adequate prediction is necessary. Cation exchange between a brine and the clays within a reservoir rock occurs if the injected fluids have a salinity and hardness different from that of the in-place fluids. Smith, Griffith, and Hill and Lake have studied this problem and have shown the significance of the cation-exchange capacity (CEC) of the clays and the selectivity of the cation species with the clays. The clay selectivity is a measure of the preference of the clay for monovalent vs. divalent cations; for a given brine, smaller values indicate a higher fraction of the clays complexed by the divalent cations. Further, Hill and Lake concluded that the law of mass action is the best model with which to describe the process. Smith, and Hill and Lake, also showed that calcium and magnesium ions have the same selectivity with the clays vs. sodium, and hence they can be treated as a single ionic species. Hill and Lake extended their study to systems containing surfactants. They found that cation exchange in the presence of a surfactant system was complicated by interaction between surfactant and divalent cations. To describe the levels of hardness measured in the presence of surfactant micelles, they postulated the formation of a divalent-cation/surfactant complex and modeled the phenomenon with a mass-action isotherm. Gupta provided phenomenon with a mass-action isotherm. Gupta provided additional data supporting the formation of such a complex. Hirasaki and Lawson proposed a Donnan equilibrium model to describe the association of sodium and calcium with the micelles, and they estimated selectivity values from the resulting expressions. Hirasaki has incorporated a mass-action model, surfactant adsorption, and electroneutrality conditions with the mass balances neglecting dispersion to obtain a description of cation exchange during single-phase-flow in porous media. He has solved the system of equations using a method-of-characteristics approach and has been able to describe the experiments of Hill and Lake and Gupta showing good agreement between experiment and theory. The model is limited to one surfactant species and two cations-one monovalent and one divalent. The surfactant system used by Gupta closely conforms to these limitations. The micellar system used by Hill and Lake, however, was composed of two petroleum sulfonates and sodium alkyl ethoxysulfate (Neodol 25–3S). Nevertheless, Hirasaki assumed the surfactant mixture to be acting as a single surfactant species. This paper deals with the cation exchange that occurs during the propagation of a micellar system containing BEW sulfonate. The objective is to history-match limited tests in Berea cores and then to use the understanding gained and parameter values obtained to predict hardness concentrations in field cores over a wide range of micellar compositions. To correlate the Berea data and to extrapolate to other conditions, the approach of Hirasaki is desirable because of its simplicity. However, the complex composition of the BEW sulfonate micellar system, as well as a desire to include an adsorption isotherm and dispersion-important for small slug processes-precluded the straightforward use of the equations and the solution that he put forward. SPEJ P. 580

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