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Vilas G. Gaikar - One of the best experts on this subject based on the ideXlab platform.
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hydrotropic extraction process for recovery of forskolin from coleus forskohlii roots
Industrial & Engineering Chemistry Research, 2009Co-Authors: Sanjay P Mishra, Vilas G. GaikarAbstract:A simple and rapid method based on hydrotropic solubilization is developed for isolation of forskolin from coleus forskohlii roots. The plant cells are permeabilized by aqueous Hydrotrope solutions followed by extraction and solubilization of forskolin into the Hydrotrope solutions of alkyl benzene sulfonates and carboxylates. The solubility of forskolin is increased by 350 times in the hydrotropic solutions and it is possible to recover 85% pure forskolin from the hydrotropic solutions by simple dilution with water. The purity of the recovered forskolin decreased from 85% to 70% on decreasing particle size of the roots. Nearly 80% of the forskolin having 50% purity was recovered from the coleus roots using 2.0 mol/dm3 aqueous sodium cumene sulfonate (Na−CS) solutions at 363 K. Na−CS showed the most efficient solubilization of forskolin from the Coleus roots among all the other Hydrotropes.
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effect of temperature on aggregation behavior of aqueous solutions of sodium cumene sulfonate
Journal of Molecular Liquids, 2007Co-Authors: Vikrant B Wagle, Prajesh S Kothari, Vilas G. GaikarAbstract:Aqueous solutions of sodium cumene sulfonate are characterized by various experimental techniques for its aggregation behavior as a function of temperature. Surface tensiometry, volumetric changes, vapor pressure osmometry, fluorescence polarization studies and enthalpy changes show changes in the solutions with increasing concentration and temperature. The apparent and partial molal volumes of the Hydrotrope, derived from the density measurements, show a sharp increase at a characteristic minimum Hydrotrope concentration. The osmotic coefficient of NaCS, obtained from vapor pressure osmometry, shows a significant deviation indicating aggregation of the Hydrotrope molecules in aqueous solutions. NaCS, when used as an intrinsic fluorescent probe, reveals a non-polar environment in the aggregate with substantial microviscosity. The enthalpies of micellization obtained directly from the calorimetric measurements show a trend towards lower values with increasing temperature.
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recovery of diosgenin from dioscorea rhizomes using aqueous hydrotropic solutions of sodium cumene sulfonate
Industrial & Engineering Chemistry Research, 2004Co-Authors: Sanjay P Mishra, Vilas G. GaikarAbstract:Aqueous solutions of aromatic Hydrotropes were investigated for cell permeabilization and extraction of dioscin from dioscorea rhizomes. The extracted dioscin was further hydrolyzed in the same hydrotropic solutions to diosgenin without significant decomposition to 3,5-diene, unlike in the conventional process. The parameters affecting the extraction of dioscin, such as the nature and concentration of the Hydrotrope, the temperature, and the particle size, were optimized. Sodium cumene sulfonate was the most efficient Hydrotrope for the extraction of dioscin and also for its hydrolysis to diosgenin at 353 K. Diosgenin precipitates from aqueous NaCS solutions with >95% purity at 293 K because of its poor solubility in aqueous solutions.
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solubility of o p hydroxyacetophenones in aqueous solutions of sodium alkyl benzene sulfonate Hydrotropes
Journal of Chemical & Engineering Data, 2004Co-Authors: Y. P. Koparkar, Vilas G. GaikarAbstract:Hydrotropes enhance solubility of water-insoluble or sparingly soluble solutes such as o- and p-hydroxyacetophenones (HAPs) in aqueous solutions. The solubility of HAPs is experimentally determined in aqueous solutions of sodium cumene sulfonate (NaCS), sodium p-xylene sulfonate (NaXS), and sodium p-toluene sulfonate (NaPTS). The solubility of phenols increases almost by an order of magnitude at higher concentrations of the Hydrotropes in the order NaPTS, NaXS, and NaCS, at a given temperature. The solubility o-HAP was twice that of p-HAP in the NaCS solutions, and a similar trend was observed in other Hydrotrope solutions. The solubility data was fitted in the Association model of hydrotropy to estimate the Hydrotrope−Hydrotrope and Hydrotrope−solute interaction parameters. NaCS, the more hydrophobic Hydrotrope, shows stronger interaction with the phenols and a higher association constant.
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small angle neutron scattering studies of mixed cetyl trimethylammonium bromide butyl benzene sulfonate solutions
Langmuir, 2002Co-Authors: O R Pal, Vilas G. Gaikar, J V Joshi, P S Goyal, V K AswalAbstract:The effect of Hydrotropes, sodium salts of butyl benzene sulfonate (Na-BBS), viz., n-butyl benzene sulfonate (Na-nBBS), iso-butyl benzene sulfonate (Na-iBBS), and tert-butyl benzene sulfonate (Na-tBBS), on microstructures of cetyl trimethylammonium bromide (CTAB) in aqueous solutions has been studied using small-angle neutron scattering (SANS) and viscosity changes. The viscosity of CTAB solutions increased with the addition of the Hydrotropes, but differently with different isomers. This behavior is attributed to the structural differences in the Hydrotropes. The SANS studies indicated the growth of the CTAB micelles on the addition of the Hydrotropes while the micellar shape changed from sphere to ellipsoid depending upon the structure of the Hydrotrope. Na-nBBS showed the highest aggregation number and a lower fractional charge on the micelles as compared to the sterically hindered Na-tBBS, at the same concentration.
Nagendra N Gandhi - One of the best experts on this subject based on the ideXlab platform.
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ASSOCIATION MODEL OF HYDROTROPY FOR THE EFFECT OF HydrotropeS ON SOLUBILITY AND MASS TRANSFER COEFFICIENT OF ACETYLSALICYLIC ACID Research Article
2012Co-Authors: S. Thenesh Kumar, Nagendra N GandhiAbstract:Hydrotropes enhance the solubility and mass transfer coefficient of water-insoluble or sparingly soluble acetylsalicylic acid in aqueous solutions. The solubility of acetylsalicylic acid is experimentally determined in aqueous solutions of Hydrotropes such as sodium salicylate, sodium benzoate, nicotinamide and urea under a wide range of Hydrotrope concentrations (0 to 3.0) mol/L and different system temperatures T = (303 to 333) K. The maximum enhancement factor value has been determined for both solubility and mass transfer coefficient. The effectiveness of Hydrotropes was measured in terms of Setschnew constant K s and reported for all Hydrotropes used in this study. The solubility data was fitted in the Association model of hydrotropy to estimate the Hydrotrope-Hydrotrope K hh and Hydrotrope-solute K hs
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effect of Hydrotropes on solubility and mass transfer coefficient of 1 2 dichloroethane
2012Co-Authors: Antony Bertie Morais, Nagendra N GandhiAbstract:A comprehensive investigation on the solubility and mass transfer coefficient enhancement of 1,2-dichloroethane through hydrotropy has been undertaken. The solubility and mass transfer coefficient studies were carried out using Hydrotropes such as urea, citric acid, nicotinamide and sodium salicylate under the influence of a wide range of Hydrotrope concentrations (0 to 3.0 mol/L) and different system temperatures (303 to 333 K). It has been observed that the solubility of 1,2-dichloroethane increases with increase in Hydrotrope concentration and also with system temperature. A Minimum Hydrotrope Concentration (MHC) in the aqueous phase was required to initiate significant solubilization of 1,2- dichloroethane. Consequent to the increase in solubilization of 1,2-dichloroethane, the mass transfer coefficient was also found to increase with increase in Hydrotrope concentration at 303 K . A threshold value of MHC is to be maintained to have an appreciable enhancement in the mass transfer coefficient. The maximum enhancement factor, which is the ratio of the value in the presence and absence of a Hydrotrope, has been determined for all sets of experimentations. The performance of Hydrotropes was measured in terms of setschenow constant (Ks) and reported for all Hydrotropes used in this study.
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Separation of m/p-Aminoacetophenone Using Hydrotropy
Hindawi Limited, 2012Co-Authors: M. Dhinakaran, Nagendra N GandhiAbstract:The aqueous solubilities of m/p-aminoacetophenone in different concentrations (0-3.0 mol/L) of Hydrotropes such as diethyl nicotinamide, sodium pseudocumene sulfonate and sodium thiocyanate solutions at different system temperatures (303K to 333K) were studied. The percentage extraction (%E) of m- aminoacetophenone from m/p-aminoacetophenone mixture increases with increase in Hydrotrope concentration. A Minimum Hydrotrope Concentration (MHC) in the aqueous phase was required to initiate the significance of the %E of m-aminoacetophenone. Percentage extraction (%E) is the ratio of moles of m-aminoacetophenone extracted in presence and absence of a Hydrotrope. The sensitivity and feasibility of the proposed process are examined by carrying out solubilization and equilibrium precipitation experiments with the mixtures of various compositions. The effectiveness of Hydrotropes was measured in terms of Setschenow constant Ks. The extraction data are also fitted in a polynomial equation as the function of Hydrotrope concentration. The solubilized material can be recovered by dilution with water
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Effect of Hydrotropes on Solubility and Mass Transfer Coefficient of Methyl Salicylate
Mathematical Models and Methods in Applied Sciences, 2009Co-Authors: M. Dharmendira Kumar And, Nagendra N GandhiAbstract:This paper presents a comprehensive study on the effect of citric acid, sodium benzoate, sodium salicylate, and urea (Hydrotropes) on the solubility and mass transfer coefficient for the extraction of methyl salicylate in water. A Minimum Hydrotropic Concentration (MHC) in the range between 0.20 and 0.90 mol/L was found essential to show a significant increase in the solubility and mass transfer coefficient for the methyl salicylate−water system. The solubility of methyl salicylate has been increased to a maximum value of 22.84 in the presence of citric acid as Hydrotrope at concentration of 2.00 mol/L and temperature of 333 K. The maximum enhancement factor for the mass transfer coefficient was found to be 7.88 in the presence of citric acid as Hydrotrope at a concentration of 2.00 mol/L at 303 K at 600 rpm. The Setschenow constant, Ks, a measure of the effectiveness of the Hydrotrope, has been determined for each case, and the highest value has been observed as 0.743 in the case of citric acid.
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effect of Hydrotropes on the solubility and mass transfer coefficient of benzyl benzoate in water
Journal of Chemical & Engineering Data, 2005Co-Authors: N Meyyappan, Nagendra N GandhiAbstract:This work presents a comprehensive study on the effect of Hydrotropes on the solubility and mass transfer coefficient of benzyl benzoate in water. The solubility studies were performed using Hydrotropes such as tri-sodium citrate, urea, sodium benzoate, and sodium salicylate for various concentrations in the range from (0 to 3.0) mol·L-1 and system temperatures ranging from T = (303 to 333) K. The performance of the Hydrotropes was measured in terms of the Setschenow constant (KS). It was found that the solubility of benzyl benzoate increases with an increase in Hydrotrope concentration and also with system temperature. A minimum Hydrotrope concentration (MHC) in the aqueous phase was required to initiate significant solubilization of benzyl benzoate. Consequent to the increase in solubilization of benzyl benzoate, the mass transfer coefficient was also found to increase with an increase in Hydrotrope concentration. All Hydrotropes used in this work showed an enhancement in the solubility and mass transfe...
Seishi Shimizu - One of the best experts on this subject based on the ideXlab platform.
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enhanced dissolution of ibuprofen using ionic liquids as catanionic Hydrotropes
Physical Chemistry Chemical Physics, 2018Co-Authors: Tânia E. Sintra, Seishi Shimizu, Sonia P M Ventura, Karina Shimizu, J Canongia N Lopes, João A. P. CoutinhoAbstract:The therapeutic effectiveness of a drug largely depends on its bioavailability, and thus ultimately on its aqueous solubility. Hydrotropes are compounds able to enhance the solubility of hydrophobic substances in aqueous media and therefore are extensively used in the formulation of drugs and personal care products. Recently, some ionic liquids were shown to display a strong ability to enhance the solubility of biomolecules through hydrotropy. In this work, the impact of the ionic liquid chemical structures and their concentration on the solubility of ibuprofen was evaluated and compared with the performance of conventional Hydrotropes. The results obtained clearly evidence the exceptional capacity of ionic liquids to enhance the solubility of ibuprofen. [C4C1im][SCN] and [C4C1im][N(CN)2] seem to be the most promising ionic liquids for ibuprofen solubilisation, where an increase in the solubility of 60- and 120-fold was observed with ionic liquid concentrations of circa 1 mol kg−1, respectively. Dynamic light scattering and molecular dynamics simulations were used to investigate the mechanism of the IL-mediated drug solubility and the results obtained indicate that the structure of aqueous solutions of ionic liquids and the role it plays in the formation of ionic liquid-drug aggregates is the mechanism driving the hydrotropic dissolution.
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Unifying hydrotropy under Gibbs phase rule
Physical chemistry chemical physics : PCCP, 2017Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:The task of elucidating the mechanism of solubility enhancement using Hydrotropes has been hampered by the wide variety of phase behaviour that Hydrotropes can exhibit, encompassing near-ideal aqueous solution, self-association, micelle formation, and micro-emulsions. Instead of taking a field guide or encyclopedic approach to classify Hydrotropes into different molecular classes, we take a rational approach aiming at constructing a unified theory of hydrotropy based upon the first principles of statistical thermodynamics. Achieving this aim can be facilitated by the two key concepts: (1) the Gibbs phase rule as the basis of classifying the Hydrotropes in terms of the degrees of freedom and the number of variables to modulate the solvation free energy; (2) the Kirkwood-Buff integrals to quantify the interactions between the species and their relative contributions to the process of solubilization. We demonstrate that the application of the two key concepts can in principle be used to distinguish the different molecular scenarios at work under apparently similar solubility curves observed from experiments. In addition, a generalization of our previous approach to solutes beyond dilution reveals the unified mechanism of hydrotropy, driven by a strong solute-Hydrotrope interaction which overcomes the apparent per-Hydrotrope inefficiency due to Hydrotrope self-clustering.
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The origin of cooperative solubilisation by Hydrotropes
Physical chemistry chemical physics : PCCP, 2016Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:The signature of hydrotropic solubilisation is the sigmoidal solubility curve; when plotted against Hydrotrope concentration, solubility increases suddenly after the minimum Hydrotrope concentration (MHC), and reaches a plateau at higher Hydrotrope concentrations. This sigmoidal curve is characteristic of cooperative phenomena, yet the true molecular basis of hydrotropic cooperativity has long remained unclear. Here we develop a theory, derived from the first principles of statistical thermodynamics using partially-open ensembles, to identify the origin of hydrophobic cooperativity. Our theory bears a close resemblance to the cooperative binding model used for protein–ligand binding. The cause of cooperativity is the enhancement of the Hydrotrope m-body interaction induced by the presence of the solute; m can be estimated from the experimental solubility data.
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Hydrotrope accumulation around the drug the driving force for solubilization and minimum Hydrotrope concentration for nicotinamide and urea
Physical Chemistry Chemical Physics, 2015Co-Authors: Jonathan J Booth, Steven Abbott, Muhiadin Omar, Seishi ShimizuAbstract:Nicotinamide is an effective non-micellar Hydrotrope (solubilizer) for drugs with low aqueous solubility. To clarify the molecular basis of nicotinamide’s hydrotropic effectiveness, we present here a rigorous statistical thermodynamic theory, based on the Kirkwood–Buff theory of solutions, and our recent application of it to hydrotropy. We have shown that (i) nicotinamide self-association reduces solubilization efficiency, contrary to the previous hypothesis which claimed that self-association drives solubilization and (ii) the minimum Hydrotrope concentration (MHC), namely, the threshold concentration above which solubility suddenly increases, is caused not by the bulk-phase self-association of nicotinamides as has been postulated previously, but by the enhancement of nicotinamide–nicotinamide interaction around the drug molecules. We have thus established a new view of hydrotropy – it is nicotinamide’s non-stoichiometric accumulation around the drug that is the basis of solubility increase above MHC.
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Hydrotropy: monomer-micelle equilibrium and minimum Hydrotrope concentration.
The journal of physical chemistry. B, 2014Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:Drug molecules with low aqueous solubility can be solubilized by a class of cosolvents, known as Hydrotropes. Their action has often been explained by an analogy with micelle formation, which exhibits critical micelle concentration (CMC). Indeed, Hydrotropes also exhibit “minimum Hydrotrope concentration” (MHC), a threshold concentration for solubilization. However, MHC is observed even for nonaggregating monomeric Hydrotropes (such as urea); this raises questions over the validity of this analogy. Here we clarify the effect of micellization on hydrotropy, as well as the origin of MHC when micellization is not accompanied. On the basis of the rigorous Kirkwood-Buff (KB) theory of solutions, we show that (i) micellar hydrotropy is explained also from preferential drug–Hydrotrope interaction; (ii) yet micelle formation reduces solubilization effeciency per Hydrotrope molecule; (iii) MHC is caused by Hydrotrope–Hydrotrope self-association induced by the solute (drug) molecule; and (iv) MHC is prevented by hy...
Nobuyuki Matubayasi - One of the best experts on this subject based on the ideXlab platform.
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Unifying hydrotropy under Gibbs phase rule
Physical chemistry chemical physics : PCCP, 2017Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:The task of elucidating the mechanism of solubility enhancement using Hydrotropes has been hampered by the wide variety of phase behaviour that Hydrotropes can exhibit, encompassing near-ideal aqueous solution, self-association, micelle formation, and micro-emulsions. Instead of taking a field guide or encyclopedic approach to classify Hydrotropes into different molecular classes, we take a rational approach aiming at constructing a unified theory of hydrotropy based upon the first principles of statistical thermodynamics. Achieving this aim can be facilitated by the two key concepts: (1) the Gibbs phase rule as the basis of classifying the Hydrotropes in terms of the degrees of freedom and the number of variables to modulate the solvation free energy; (2) the Kirkwood-Buff integrals to quantify the interactions between the species and their relative contributions to the process of solubilization. We demonstrate that the application of the two key concepts can in principle be used to distinguish the different molecular scenarios at work under apparently similar solubility curves observed from experiments. In addition, a generalization of our previous approach to solutes beyond dilution reveals the unified mechanism of hydrotropy, driven by a strong solute-Hydrotrope interaction which overcomes the apparent per-Hydrotrope inefficiency due to Hydrotrope self-clustering.
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The origin of cooperative solubilisation by Hydrotropes
Physical chemistry chemical physics : PCCP, 2016Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:The signature of hydrotropic solubilisation is the sigmoidal solubility curve; when plotted against Hydrotrope concentration, solubility increases suddenly after the minimum Hydrotrope concentration (MHC), and reaches a plateau at higher Hydrotrope concentrations. This sigmoidal curve is characteristic of cooperative phenomena, yet the true molecular basis of hydrotropic cooperativity has long remained unclear. Here we develop a theory, derived from the first principles of statistical thermodynamics using partially-open ensembles, to identify the origin of hydrophobic cooperativity. Our theory bears a close resemblance to the cooperative binding model used for protein–ligand binding. The cause of cooperativity is the enhancement of the Hydrotrope m-body interaction induced by the presence of the solute; m can be estimated from the experimental solubility data.
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Hydrotropy: monomer-micelle equilibrium and minimum Hydrotrope concentration.
The journal of physical chemistry. B, 2014Co-Authors: Seishi Shimizu, Nobuyuki MatubayasiAbstract:Drug molecules with low aqueous solubility can be solubilized by a class of cosolvents, known as Hydrotropes. Their action has often been explained by an analogy with micelle formation, which exhibits critical micelle concentration (CMC). Indeed, Hydrotropes also exhibit “minimum Hydrotrope concentration” (MHC), a threshold concentration for solubilization. However, MHC is observed even for nonaggregating monomeric Hydrotropes (such as urea); this raises questions over the validity of this analogy. Here we clarify the effect of micellization on hydrotropy, as well as the origin of MHC when micellization is not accompanied. On the basis of the rigorous Kirkwood-Buff (KB) theory of solutions, we show that (i) micellar hydrotropy is explained also from preferential drug–Hydrotrope interaction; (ii) yet micelle formation reduces solubilization effeciency per Hydrotrope molecule; (iii) MHC is caused by Hydrotrope–Hydrotrope self-association induced by the solute (drug) molecule; and (iv) MHC is prevented by hy...
Mikhail A. Anisimov - One of the best experts on this subject based on the ideXlab platform.
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dual action of Hydrotropes at the water oil interface
Journal of Physical Chemistry C, 2017Co-Authors: Andrei A. Novikov, Jeffery B. Klauda, Anton P. Semenov, Vladimir N. Kuryakov, Viviana Monjegalvan, Mikhail A. AnisimovAbstract:Hydrotropes are substances containing small amphiphilic molecules, which increase solubility of nonpolar (hydrophobic) substances in water. Hydrotropes may form dynamic clusters (less or about 1 ns lifetime) with water molecules; such clusters can be viewed as “pre-micelles” or as “micellar-like” structural fluctuations. We present the results of experimental and molecular dynamics (MD) simulation studies of interfacial phenomena and liquid–liquid equilibrium in the mixtures of water and cyclohexane with the addition of a typical nonionic Hydrotrope, tertiary butanol. The interfacial tension between the aqueous and oil phases was measured by Wilhelmy plate and spinning drop methods with overlapping conditions in excellent agreement between techniques. The correlation length of the concentration fluctuations, which is proportional to the thickness of the interface near the liquid–liquid critical point, was measured by dynamic light scattering. In addition, we studied the interfacial tension and water–oil i...
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Dual Action of Hydrotropes at the Water/Oil Interface
2017Co-Authors: Andrei A. Novikov, Jeffery B. Klauda, Anton P. Semenov, Viviana Monje-galvan, Vladimir N. Kuryakov, Mikhail A. AnisimovAbstract:Hydrotropes are substances containing small amphiphilic molecules, which increase solubility of nonpolar (hydrophobic) substances in water. Hydrotropes may form dynamic clusters (less or about 1 ns lifetime) with water molecules; such clusters can be viewed as “pre-micelles” or as “micellar-like” structural fluctuations. We present the results of experimental and molecular dynamics (MD) simulation studies of interfacial phenomena and liquid–liquid equilibrium in the mixtures of water and cyclohexane with the addition of a typical nonionic Hydrotrope, tertiary butanol. The interfacial tension between the aqueous and oil phases was measured by Wilhelmy plate and spinning drop methods with overlapping conditions in excellent agreement between techniques. The correlation length of the concentration fluctuations, which is proportional to the thickness of the interface near the liquid–liquid critical point, was measured by dynamic light scattering. In addition, we studied the interfacial tension and water–oil interfacial profiles by MD simulations of a model representing this ternary system. Both experimental and simulation studies consistently demonstrate a spectacular crossover between two limits in the behavior of the water–oil interfacial properties upon addition of the Hydrotrope: at low concentrations the Hydrotrope acts as a surfactant, decreasing the interfacial tension by adsorption of Hydrotrope molecules on the interface, while at higher concentrations it acts as a cosolvent with the interfacial tension vanishing in accordance with a scaling power-law upon approach to the liquid–liquid critical point. It is found that the relation between the thickness of the interface and the interfacial tension follows a scaling law in the entire range of interfacial tensions, from a “sharp” interface in the absence of the Hydrotrope to a “smooth” interface near the critical point. We also demonstrate the generic nature of the dual behavior of Hydrotropes by comparing the studied ternary system with systems containing different hydrocarbons and Hydrotropes
