Articles de revues : « Pure and mixed solvent systems »

1

Ekezie, C., G. Cookey et J. Maduelosi. « Volumetric and viscometric studies of binary mixtures of methanol and some alkyl acetates at varying temperatures ». South African Journal of Chemistry 77 (2023) : 133–37. http://dx.doi.org/10.17159/0379-4350/2023/v77a16.

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The degree of molecular interactions between mixed solvent molecules and thus ideal behavior results from the molecular architecture and chemical nature of component solvents. This understanding is essential in the design and applications of both pure and mixed solvent systems. Density and viscosity measurements of pure and binary mixtures of methanol and n-methyl acetate, n-butyl acetate, and n-pentyl acetate were carried out at different compositions of methanol and temperatures of 25, 30, 35, 40 °C. The experimental data obtained were correlated to the Redlich-Kister equation from where the excess functions; excess molar volumes, excess viscosities, excess Gibbs free energies of activation for viscous flow, fitting coefficients and standard deviations were obtained. The viscosity values were correlated with Hind et al, Kendral and Monroe, Grunberg and Nissan and Frenkel semi empirical models to ascertain the best fit for the systems. The results obtained have been discussed in terms of the structural differences and nature of the interactions between molecules of the mixed solvents.

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Wang, Luoluo, Minchang Wang, Ying Kang, Yong Zhu, Hai Chang et Ning Liu. « Solubility Determination and Comprehensive Analysis of the New Heat-Resistant Energetic Material TNBP ». Molecules 28, n^o 6 (7 mars 2023) : 2424. http://dx.doi.org/10.3390/molecules28062424.

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To improve the crystal quality of 4,8-bis(2,4,6-trinitrophenyl)difurazolo [3,4-b:3′,4′-e] pyrazine (TNBP), the solubility of TNBP in organic solvents (six pure and four mixed solvents) was determined by the laser monitoring technique from 293.15 to 353.15 K. The results showed that the solubility was positively correlated with the increase in the experimental temperature and the main solvent content, except for the co-solvent phenomenon in the DMSO + ethyl acetate solvent mixture. To explain the dissolution behavior of TNBP, the KAT-SER model was analyzed for pure solvent systems, and it was found that hydrogen bonding alkalinity and self-cohesiveness were the main influencing factors. The free energy of solvation and radial distribution function of TNBP in mixed solvents were also obtained by molecular dynamics simulation, and the effect of solute–solvent and solvent–solvent interactions on the solubility trend was analyzed. The experimental data were correlated using three empirical equations (van’t Hoff equation, modified Apelblat equation, and λh equation), and the deviation analysis showed the good applicability of the modified Apelblat model. Furthermore, the dissolution of TNBP was heat-absorbing and not spontaneous, according to the thermodynamic characteristics estimated by the van’t Hoff equation.

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Shamsher Ali, Shamsher Ali, Shabir Hussain Shabir Hussain et Irfan Ali and Syed Azhar Ali Irfan Ali and Syed Azhar Ali. « Determination of Thermodynamic Parameters from the Dissolution of Strontium Hydroxide in Water and Mixed Solvent Systems by pH-Metric Method ». Journal of the chemical society of pakistan 42, n^o 1 (2020) : 57. http://dx.doi.org/10.52568/000621.

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In this study, saturated solutions of Sr(OH)2 in pure water and in mixed solvent systems (methanol - water, ethanol - water, 1-propanol - water, and 2-propanol - water) at two temperatures were prepared and titrated with standard HCl solution by using pH metry. Using these titration data, the molar solubility (s), solubilty product (Ksp) and Gibbs free energy (Go), entropy change (ΔSand#176;) and enthalpy change (ΔHand#176;) for dissolution of strontium hydroxide was determined. At room temperature (20and#176;C), the s, Ksp, ∆Go were found to be 4.28 x 10-2 mol L-1, 3.13 x 10-4 mol3L-3 and 19.70 kJ mol-1 respectively. The ΔHand#176; and ΔSand#176; of the reaction is 2.90 kJ mol-1 and – 60.80 J. mol-1 K-1. With increasing percentage content of organic solvent in mixed solvents, the molar solubility and Ksp decreased and ∆Go, ΔHand#176; and ΔSand#176; values increased. The results were correlated with the dielectric constant value of the solvents used in the study.

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Shamsher Ali, Shamsher Ali, Shabir Hussain Shabir Hussain et Irfan Ali and Syed Azhar Ali Irfan Ali and Syed Azhar Ali. « Determination of Thermodynamic Parameters from the Dissolution of Strontium Hydroxide in Water and Mixed Solvent Systems by pH-Metric Method ». Journal of the chemical society of pakistan 42, n^o 1 (2020) : 57. http://dx.doi.org/10.52568/000621/jcsp/42.01.2020.

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In this study, saturated solutions of Sr(OH)2 in pure water and in mixed solvent systems (methanol - water, ethanol - water, 1-propanol - water, and 2-propanol - water) at two temperatures were prepared and titrated with standard HCl solution by using pH metry. Using these titration data, the molar solubility (s), solubilty product (Ksp) and Gibbs free energy (Go), entropy change (ΔSand#176;) and enthalpy change (ΔHand#176;) for dissolution of strontium hydroxide was determined. At room temperature (20and#176;C), the s, Ksp, ∆Go were found to be 4.28 x 10-2 mol L-1, 3.13 x 10-4 mol3L-3 and 19.70 kJ mol-1 respectively. The ΔHand#176; and ΔSand#176; of the reaction is 2.90 kJ mol-1 and – 60.80 J. mol-1 K-1. With increasing percentage content of organic solvent in mixed solvents, the molar solubility and Ksp decreased and ∆Go, ΔHand#176; and ΔSand#176; values increased. The results were correlated with the dielectric constant value of the solvents used in the study.

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Roy, Nath, Lovely Sarkar et Kumar Sarkar. « Study of solute-solvent interactions of nicotinic acid and benzoic acid in methanol and its binary solvent systems ». Journal of the Serbian Chemical Society 73, n^o 12 (2008) : 1235–46. http://dx.doi.org/10.2298/jsc0812235r.

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The apparent molar volumes, ?V, and viscosity B-coefficients, B, for nicotinic acid (NA) and benzoic acid (BA) in mixed solvents containing 10, 20, 30 mass % of n-amyl alcohol (n-AmOH) or isoamyl alcohol (i-AmOH) in methanol and in pure methanol (MeOH) were determined from the solution density and viscosity measurements at 298.15 K as function of concentrations of NA and BA. These results were, in conjunction with the results obtained in pure methanol, used to deduce the partial molar volumes of transfer, 0 ??V , and viscosity B-coefficients of transfer, ?B, for NA and BA from methanol to different mixed methanol solvents, in order to rationalize various interactions in the ternary solutions. An increase in the transfer properties of NA and BA with increasing mass % of n-AmOH and i-AmOH in methanol was observed and explained by the effect of structural changes and preferential solvation. Also, the free energies of viscous flow, ? 0? 1 ? and ? 0? ?2 , per mole of solvent and solute, respectively, were calculated and analyzed on the basis of the transition state theory of relative viscosity.

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Esan, Olaseni Segun, Medinat Olubunmi Osundiya, Christopher Olumuyiwa Aboluwoye, Owoyomi Olanrewaju et Jide Ige. « Thermodynamic and Interfacial Properties of DTABr/CTABr Mixed Surfactant Systems in Ethanolamine/Water Mixtures : A Conductometry Study ». ISRN Thermodynamics 2013 (17 décembre 2013) : 1–7. http://dx.doi.org/10.1155/2013/280101.

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Mixed-micelle formation in the binary mixtures of dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr) surfactants in water-ethanolamine mixed solvent systems has been studied by conductometric method in the temperature range of 298.1 to 313.1 K at 5 K intervals. It was observed that the presence of ethanolamine forced the formation of mixed micelle to lower total surfactant concentration than in water only. The synergistic interaction was quantitatively investigated using the theoretical models of Clint and Rubingh. The interaction parameter β12 was negative at all the mole fractions of DTABr in the surfactant mixtures indicating a strong synergistic interaction, with the presence of ethanolamine in the solvent system resulting in a more enhanced synergism in micelle formation than in water only. The free energy of micellization ΔGM values was more negative in water-ethanolamine mixed solvent system than in pure water indicating more spontaneity in mixed micelle formation in the presence of ethanolamine than in pure water.

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Yin, Dai-ping, Meng-xi Liu, Hua-lin Fu, Gang Shu, Jian-yu Zhou, Xue-yan Qing et Wen-bin Wu. « Solubility of Trimethoprim in Selected Pure Solvents and (Water + Ethanol/2-Propanol) Mixed-Solvent Systems ». Journal of Chemical & ; Engineering Data 61, n^o 1 (22 décembre 2015) : 404–11. http://dx.doi.org/10.1021/acs.jced.5b00616.

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Wang, Li, Rui Xu, Ruohua Liu, Peng Ge, Wei Sun et Mengjie Tian. « Self-Assembly of NaOL-DDA Mixtures in Aqueous Solution : A Molecular Dynamics Simulation Study ». Molecules 26, n^o 23 (24 novembre 2021) : 7117. http://dx.doi.org/10.3390/molecules26237117.

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The self-assembly behaviors of sodium oleate (NaOL), dodecylamine (DDA), and their mixtures in aqueous solution were systematically investigated by large-scale molecular dynamics simulations, respectively. The interaction mechanisms between the surfactants, as well as the surfactants and solvent, were revealed via the radial distribution function (RDF), cluster size, solvent-accessible surface area (SASA), hydrogen bond, and non-bond interaction energy. Results showed that the molecules more easily formed aggregates in mixed systems compared to pure systems, indicating higher surface activity. The SASA values of DDA and NaOL decreased significantly after mixing, indicating a tighter aggregation of the mixed surfactants. The RDF results indicated that DDA and NaOL strongly interacted with each other, especially in the mixed system with a 1:1 molar ratio. Compared to van der Waals interactions, electrostatic interactions between the surfactant molecules were the main contributors to the improved aggregation in the mixed systems. Besides, hydrogen bonds were found between NaOL and DDA in the mixed systems. Therefore, the aggregates in the mixed systems were much more compact in comparison with pure systems, which contributed to the reduction of the repulsive force between same molecules. These findings indicated that the mixed NaOL/DDA surfactants had a great potential in application of mineral flotation.

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Satyanarayana, D., et P. R. Chatterji. « Swelling characteristics of amphiphilic polymer brushes in pure and mixed solvent systems ». Polymer 34, n^o 17 (septembre 1993) : 3682–86. http://dx.doi.org/10.1016/0032-3861(93)90053-d.

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Somsen, G. « Interactions in solutions : A calorimetric study of pure and mixed solvent systems ». Pure and Applied Chemistry 63, n^o 12 (1 janvier 1991) : 1687–96. http://dx.doi.org/10.1351/pac199163121687.

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Jia, Qing Xiu, Chao Ming Shi et Guo Liang Zhao. « Influence of Low Boiling Point Nonsolvents on Morphologies of PA6 Electrospun Fibers ». Advanced Materials Research 332-334 (septembre 2011) : 1322–25. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.1322.

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In the present contribution, ultra-high molecular polyamide 6 (PA6) solutions were prepared in various pure and mixed-solvent systems and later electrospun with the polarity of the emitting electrode. The PA6 concentration in the as-prepared solutions was fixed at 4 wt%. Some of the solution properties, i.e., surface tension, and conductivity, were measured. In the mixed-solvent systems, formic acid (FA) was blended with dichloromethane (DCM), trichloromethane (THM), and acetone, the influences of low boiling point nonsolvents on morphological appearance and sizes of the resulting PA6 electrospun fibers were also investigated.

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Duereh, Alif, Amata Anantpinijwatna et Panon Latcharote. « Prediction of Solvatochromic Polarity Parameters for Aqueous Mixed-Solvent Systems ». Applied Sciences 10, n^o 23 (27 novembre 2020) : 8480. http://dx.doi.org/10.3390/app10238480.

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Solvent polarity is important data being used in solvent selections for preliminary engineering design of chemical processes. In this work, a predictive model is proposed for estimating the solvatochromic polarity of electronic transition energy (ET) of Reichardt indicator for aqueous mixtures. To validate the model, the ET values of eighteen aqueous mixtures collected from the literature were used. The predictive model provided a good estimation of ET values with an overall deviation of 2.1%, compared with an ideal model (5.1%) from the mole fraction average. The linear relationship of the contribution factor of hydrogen bond donor interactions (CFHBD) in the predictive model with Kamlet–Taft acidity was newly proposed in order to extend the model for other aqueous mixtures. The predictive model is applicable to many aqueous mixtures and simply requires three properties of pure components as: (i) ET values, (ii) gas-phase dipole moment and (iii) Kamlet–Taft acidity.

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Acree, William E., Abolghasem Jouyban et Fleming Martinez. « Comment on “Solubility of Trimethoprim in Selected Pure Solvents and (Water + Ethanol/2-Propanol) Mixed-Solvent Systems” ». Journal of Chemical & ; Engineering Data 62, n^o 3 (2 février 2017) : 1157–60. http://dx.doi.org/10.1021/acs.jced.6b00940.

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Aliwarga, Lienda, Herri Susanto, Reynard Reynard et Agnes Veronica Victoria. « UNIFAC Model for Liquid-Liquid Phase Equilibrium of Penicillin G and 6-APA System ». Jurnal Kimia Valensi 5, n^o 2 (30 novembre 2019) : 185–93. http://dx.doi.org/10.15408/jkv.v5i2.9869.

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This study investigated the effect of pH and type of solvent on liquid-liquid phase equilibrium in the system of pure penicillin G and mixed penicillin G with 6-APA. Penicillin G extraction was carried out in a pH range of 2.0–5.0 at 4 oC using several types of solvents. The liquid-liquid phase equilibrium mathematical model is prepared assuming that a single stage of thermodynamic equilibrium occurs in a batch process of liquid-liquid extraction. The coefficient of activity was calculated by the UNIFAC method. From the experiment, it was found that the extraction process of penicillin G was strongly influenced by pH of the solution. The highest yield of extraction was achieved with different solvents in the two types of solution. For pure penicillin G system, the highest yields was obtained in n-butyl acetate solvent (95.51%) while for penicillin G mixture with 6-APA, it was obtained in methyl iso-butyl ketone solvent (92.6%). The UNIFAC model have been tested against five three-component liquid-liquid phase equilibrium systems at pH 2.0 and 2.5. It was able to estimate the concentration of penicillin G in the organic phase with a relatively average error between experiment and calculation of 8.32%

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Gill, Dip Singh, Lindsay Byrne et Terry I. Quiekenden. « 63Cu Nuclear Magnetic Resonance and Viscosity Studies of Copper (I) Perchlorate in Mixed Solvents Containing Acetonitrile ». Zeitschrift für Naturforschung A 53, n^o 12 (1 décembre 1998) : 1004–8. http://dx.doi.org/10.1515/zna-1998-1213.

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Abstract63Cu nuclear magnetic resonance and viscosity studies of 0.064 M copper (I) Perchlorate solutions have been made at 298 K in binary mixtures of acetonitrile (AN) with dimethylsulphoxide (DMSO), hexamethylphosphotriamide (HMPA), N,N-dimethylacetamide (DMA), nitromethane (NM), propylene carbonate (PC) and 3-hydroxypropionitrile (3 HPN) at several compositions of the mixtures using a 500 MHz NMR Spectrometer and Ubbelohde viscometer, respectively. The chemical shift (δ), linewidth (Δ) and line intensity (I) of the 63Cu NMR signal in these mixed solvents have been measured relative to the 63Cu signal in 0.064 M copper (I) Perchlorate (CuClO4) solution in pure AN. The quadrupolar re-laxation rates (1/T2)Q, reorientational correlation times (τR) and quadrupolar coupling constants (QCC) of the copper (I) solvates have also been estimated from the data. The QCC values show a big variation in all solvent systems with the change of solvent composition, indicating the formation of mixed com-plexes. The variation of all NMR parameters with solvent composition shows strong effects of DMSO, HMPA, and DMA on the solvation behaviour of Cu + in the first three mixtures, and relatively much weaker effects of PC, NM and 3HPN in the other three mixtures.

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Mehta, Dhruvi R., Raviprakash S. Chandra et M. M. Maisuria. « Thermodynamic Studies of Complexes of Amlodipine Besylate with Ni2+, Mg2+, Co2+ and Ca2+ cations in pure and in mixed binary solvent systems at 303.15, 313.15 and 323.15 K by Conductometric Method ». International Journal of ChemTech Research 13, n^o 1 (2020) : 206–16. http://dx.doi.org/10.20902/ijctr.2019.130125.

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The present work relates to the complexation reaction between Amlodipine Besylate[AML] with Ni2+, Mg2+, Co2+ and Ca2+ cation in dimethylsulfoxide (DMSO), pure methanol (MeOH) and their binary mixtures(DMSO-MeOH and DMSO-Water) by conductometric method. The conductance data show that the stoichiometry of the complexes formed between AML with Ni2+, Mg2+, Co2+ and Ca2+ cation in pure DMSO, pure MeOHas well as in the binary solvent mixtures was 1:1. The stability of AML complexes with Ni2+ , Mg2+, Co2+ and Ca2+ metal ion was observed to be sensitive to the nature of the solvent system. In case of DMSO-Water binary solvent systems there was a linear change in LogKf values but in case of DMSO-MeOH binary solvent systems non linear change in LogKf values observed.The negative values of ΔG0 show that the reaction is spontaneous and ability of the AML ligand to form stable complexes. However, the result shows positive value of ΔH0 which indicates that enthalpy is not driving force for the formation of the complexes. Furthermore, the positive value of ΔS0 indicates that entropy is a driving force for the complexation. The values of ΔH0 and ΔS0 for formation of the complexes were obtained from temperature dependence of the stability constants.

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Cysewski, Piotr, Tomasz Jeliński, Patryk Cymerman et Maciej Przybyłek. « Solvent Screening for Solubility Enhancement of Theophylline in Neat, Binary and Ternary NADES Solvents : New Measurements and Ensemble Machine Learning ». International Journal of Molecular Sciences 22, n^o 14 (8 juillet 2021) : 7347. http://dx.doi.org/10.3390/ijms22147347.

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Theophylline, a typical representative of active pharmaceutical ingredients, was selected to study the characteristics of experimental and theoretical solubility measured at 25 °C in a broad range of solvents, including neat, binary mixtures and ternary natural deep eutectics (NADES) prepared with choline chloride, polyols and water. There was a strong synergistic effect of organic solvents mixed with water, and among the experimentally studied binary systems, the one containing DMSO with water in unimolar proportions was found to be the most effective in theophylline dissolution. Likewise, for NADES, the addition of water (0.2 molar fraction) resulted in increased solubility compared to pure eutectics, with the highest solubilisation potential offered by the composition of choline chloride with glycerol. The ensemble of Statistica Automated Neural Networks (SANNs) developed using intermolecular interactions in pure systems has been found to be a very accurate model for solubility computations. This machine learning protocol was also applied as an extensive screening for potential solvents with higher solubility of theophylline. Such solvents were identified in all three subgroups, including neat solvents, binary mixtures and ternary NADES systems. Some methodological considerations of SANNs applications for future modelling were also provided. Although the developed protocol is focused exclusively on theophylline solubility, it also has general importance and can be used for the development of predictive models adequate for solvent screening of other compounds in a variety of systems. Formulation of such a model offers rational guidance for the selection of proper candidates as solubilisers in the designed solvents screening.

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Couture, Lorraine, Jacques E. Desnoyers et Gérald Perron. « Some thermodynamic and transport properties of lithium salts in mixed aprotic solvents and the effect of water on such properties ». Canadian Journal of Chemistry 74, n^o 2 (1 février 1996) : 153–64. http://dx.doi.org/10.1139/v96-019.

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In a continuing study on the optimization of the electrolyte medium for high-energy lithium batteries, volumes, heat capacities, and specific conductivities of LiClO4 and LiBr were measured in mixtures of γ-butyrolactone (BUTY) and 1,2-dimethoxyethane (DME) and of propylene carbonate (PC) and BUTY. These results are compared with those of the electrolytes in the pure solvents. Phase diagrams are also reported when appropriate. The effect of addition of water to these binary and ternary systems was investigated with the same techniques. The mixtures DME–BUTY, PC–DME, DME–H2O, and BUTY–H2O are typical of mixtures of aprotic solvents and mixtures of aprotic solvents and water. The electrolytes at high concentrations in aprotic solvents of low dielectric constants are largely associated. The medium still conducts electrolytically since the ion pairs are in a state that resembles to a large extent that of a molten salt. With some systems at high concentration, stable solvates persist in the solution medium, as evidenced mostly by heat capacities, and are in equilibrium with either the excess solvent or unsolvated molten salts. In mixed solvents, the properties of electrolytes can largely be predicted from the binary systems and by the coexistence of these solvates. The properties of water in DME, BUTY, or mixtures of the two solvents are modified significantly in the presence of LiBr but only slightly with LiClO4. These specific interactions, which affect the heat capacities much more than the volumes and which are especially large with the system LiBr–DME, could be responsible for the decrease in reactivity of water with lithium metal in an aprotic medium in the presence of certain electrolytes. Key words: LiClO4, LiBr, γ-butyrolactone, dimethoxyethane, propylene carbonate, lithium battery, aprotic solvent, water, association, solvates, solid–liquid phase diagrams, volumes, heat capacities, specific conductivities.

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Teixeira, Gabriel, Dinis O. Abranches, Liliana P. Silva, Sérgio M. Vilas-Boas, Simão P. Pinho, Ana I. M. C. L. Ferreira, Luís M. N. B. F. Santos, Olga Ferreira et João A. P. Coutinho. « Liquefying Flavonoids with Terpenoids through Deep Eutectic Solvent Formation ». Molecules 27, n^o 9 (20 avril 2022) : 2649. http://dx.doi.org/10.3390/molecules27092649.

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The formation of deep eutectic solvents (DES) is tied to negative deviations to ideality caused by the establishment of stronger interactions in the mixture than in the pure DES precursors. This work tested thymol and menthol as hydrogen bond donors when combined with different flavonoids. Negative deviations from ideality were observed upon mixing thymol with either flavone or flavanone, two parent flavonoids that only have hydrogen bond acceptor (HBA) groups, thus forming non-ionic DES (Type V). On the other hand, the menthol systems with the same compounds generally showed positive deviations from ideality. That was also the case with the mixtures containing the more complex hydroxylated flavonoid, hesperetin, which resulted in positive deviations when mixed with either thymol or menthol. COSMO-RS successfully predicted the behavior of the solid-liquid phase diagram of the studied systems, allowing for evaluation of the impact of the different contributions to the intermolecular interactions, and proving to be a good tool for the design of DES.

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Wegner, Wojciech, et Karol J. Fijalkowski. « Synthesis Method of Unsolvated Organic Derivatives of Metal Borohydrides ». Materials 15, n^o 23 (5 décembre 2022) : 8653. http://dx.doi.org/10.3390/ma15238653.

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A new, scalable, wet-chemistry single-pot method of synthesising pure unsolvated organic derivatives of metal borohydrides is presented. The metathetic reaction in a weakly coordinating solvent is exemplified by the synthesis of [(n-C4H9)4N][Y(BH4)4] and [Ph4P][Y(BH4)4] systems. For the latter compound, the crystal structure was solved and described. Organic borohydride salts obtained by the new method can find various applications, e.g., can be used as precursors in synthesis of hydrogen-rich mixed-metal borohydrides—promising materials for solid-state chemical storage of hydrogen.

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Alston, R. B., G. P. Kokolis et C. F. James. « CO2 Minimum Miscibility Pressure : A Correlation for Impure CO2 Streams and Live Oil Systems ». Society of Petroleum Engineers Journal 25, n^o 02 (1 avril 1985) : 268–74. http://dx.doi.org/10.2118/11959-pa.

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Abstract This paper presents an empirically derived correlation for estimating the minimum pressure required for multicontact miscible (MCM) displacement of live oil systems by pure or impure CO2 streams. Minimum miscibility pressure (MMP) has been correlated with temperature, oil C5+ molecular weight, volatile oil fraction, intermediate oil fraction, and composition of the CO2 stream. The effects of temperature and oil C5+ molecular weight on pure CO2 MMP have been well documented. However, CO2 sources are rarely pure, and solution gas usually is present in reservoir oils. The correlation presented in this paper accounts for the additional effects on MMP caused by the presence of volatile components (methane, C1; and N2) and intermediate components (ethane, C2; propane, C3; butane, C4; hydrogen sulfide, H2S; and CO2) in the reservoir oil. This correlation also is capable of estimating MMP for a contaminated or enriched CO2 stream on the basis of the pure CO2 MMP. Introduction Miscible displacements using hydrocarbon solvents have been described in the literature by many authors.1–6 The use of a slim tube apparatus for the establishment of MMP requirements for enriched or vaporizing gas drives was presented by Deffrenne et al.5 and Yarborough and Smith.7 Rutherford8 referred to these systems as conditionally miscible processes. The initial work of Rathmell et al.9 and Ballard and Smith10 illustrated that the mechanisms of CO2 displacements are similar to those of high-pressure MCM vaporizing gas drives. Since the high solubility of CO2 in reservoir oils diminishes the pressure required for miscibility to occur, a CO2 vaporizing gas drive can operate in the same manner as a lean-gas injection process, but at significantly lower pressures. Correlations for the prediction of MMP requirements for CO2 flooding are extremely helpful in the screening of candidate reservoirs for CO2 floods. Holm and Josendal11 were the first to introduce a method for estimating the MMP required for CO2 displacing oil. Other correlations for CO2 MMP have been introduced by the Natl. Petroleum Council,12 Yellig and Metcalfe,13 and Johnson and Pollin,14 as well as a new correlation from Holm and Josendal.15,16 This paper presents an empirical approach to MMP estimation. Included in this study are the effects of solution gas (live oil systems) and the effects of impure CO2 sources. Concepts of Miscible Displacement Miscible displacement is represented most easily by a ternary diagram. A pseudoternary diagram for a hypothetical hydrocarbon system is shown in Fig. 1. This is a pseudoternary representation since the apexes do not consist of pure components, but it can be used to qualitatively describe the process of miscible displacement. Fig. 1 has been divided into three areas: Zone 1, Zone 2, and Zone 3. Zone 1 represents the area of first-contact miscibility. Any solvent falling within this region can be mixed with the reservoir oil shown, such that any and all mixtures will fall outside of the two-phase region. Zone 2 represents the region of multicontact miscibility. Solvents within this area, while not initially miscible in all proportions with the reservoir oil, eventually will achieve miscibility through the repeated contacts of the reservoir oil and equilibrium fluids. There are two types of MCM processes: vaporizing gas drive, where the solvent is enriched by components vaporized from the reservoir oil, and condensing or enriched gas drive, where the solvent contributes to the enrichment of the reservoir fluid.17 Commercially viable CO2-miscible EOR processes are usually of the MCM type, because reservoir pressure requirements for this process are significantly lower than required for first contact miscibility. Zone 3 represents the area of immiscible displacement. Displacement of the reservoir oil by an fluid falling within Zone 3 will result in multiphase flow. The mass transfer between the oil and displacing fluid is such that miscibility cannot be achieved.

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Jandera, Pavel, Tomáš Hájek et Marie Růžičková. « Retention Models on Core–Shell Columns ». Journal of AOAC INTERNATIONAL 100, n^o 6 (1 novembre 2017) : 1636–46. http://dx.doi.org/10.5740/jaoacint.17-0233.

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Abstract A thin, active shell layer on core–shell columns provides high efficiency in HPLC at moderately high pressures. We revisited three models of mobile phase effects on retention for core–shell columns in mixed aqueous–organic mobile phases: linear solvent strength and Snyder–Soczewiński two-parameter models and a three-parameter model. For some compounds, two-parameter models show minor deviations from linearity due to neglect of possible minor retention in pure weak solvent, which is compensated for in the three-parameter model, which does not explicitly assume either the adsorption or the partition retention mechanism in normal- or reversed-phase systems. The model retention equation can be formulated as a function of solute retention factors of nonionic compounds in pure organic solvent and in pure water (or aqueous buffer) and of the volume fraction of an either aqueous or organic solvent component in a two-component mobile phase. With core–shell columns, the impervious solid core does not participate in the retention process. Hence, the thermodynamic retention factors, defined as the ratio of the mass of the analyte mass contained in the stationary phase to its mass in the mobile phase in the column, should not include the particle core volume. The values of the thermodynamic factors are lower than the retention factors determined using a convention including the inert core in the stationary phase. However, both conventions produce correct results if consistently used to predict the effects of changing mobile phase composition on retention. We compared three types of core–shell columns with C18-, phenyl-hexyl-, and biphenyl-bonded phases. The core–shell columns with phenyl-hexyl- and biphenyl-bonded ligands provided lower errors in two-parameter model predictions for alkylbenzenes, phenolic acids, and flavonoid compounds in comparison with C18-bonded ligands.

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Moine, Edouard, Romain Privat, Jean-Noël Jaubert, Baptiste Sirjean, Nefeli Novak, Epaminondas Voutsas et Christos Boukouvalas. « Can we safely predict solvation Gibbs energies of pure and mixed solutes with a cubic equation of state ? » Pure and Applied Chemistry 91, n^o 8 (27 août 2019) : 1295–307. http://dx.doi.org/10.1515/pac-2018-1112.

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Abstract Solvation Gibbs energies are basically defined as a chemical potential change when transferring a fixed molecule from a perfect gas to a real liquid mixture. This quantity is of special interest for many practical applications as it quantifies the degree of affinity of a solute for its solvent. Few methods are currently available in the literature for the prediction of solvation Gibbs energies. In this article, a new approach is proposed: the use of a predictive cubic equation of state (EoS). The UMR-PRU (Universal Mixing Rule Peng-Robinson UNIFAC) EoS has been selected for its known capacity to semi-predict behaviors of complex systems including polar and associating compounds (by semi-prediction, it is meant that the EoS predicts binary interaction parameters but requires pure-component properties as input parameters). UMR-PRU predictions have been compared to experimental data extracted from the extensive CompSol database (containing around 22 000 pure component data and 70 000 binary data). Accurate predictions were obtained (a mean absolute deviation of 0.36 kcal/mol was obtained for all the binary data). Finally, when using a fully-predictive approach (i.e. pure-component EoS parameters are predicted from group-contribution methods), the prediction accuracy is roughly preserved.

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Lahooti-Fard, Farzad, Mohammad Imani et Ali Akbar Yousefi. « Solvent-dependent rheological behavior of concentrated solutions of a cationic acrylic terpolymer containing self-assembled chains ». e-Polymers 15, n^o 4 (1 juillet 2015) : 279–83. http://dx.doi.org/10.1515/epoly-2015-0057.

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AbstractIt has been proved that alcohol molecules exist as cyclic and chain aggregates of different sizes in pure or mixed solvent systems. Here, it will be shown that these aggregates can radically change the rheological properties of a concentrated polymer solution containing self-assembled chains. In a previous study by the same authors, the existence of self-assembled structures in dilute solution of poly(dimethylaminoethyl methacrylate-co-methyl methacrylate-co-butyl methacrylate) in an alcoholic solvent mixture was shown according to small angle X-ray scattering results, showing that these structure were much more compact than those in acetone. This finding is based on the role of alcohol aggregates as physical cross-linkers. Here, the existence of self-assembled structures in concentrated solutions of the same terpolymer was confirmed by atomic force microscopy and rheology results both in acetone (a good solvent) and in a solvent mixture composed of acetone, ethanol and 1-propanol. For the terpolymer solutions in the solvent mixture, very little decrease in complex viscosity and shear thickening were observed at high strains and frequencies, respectively. It can be concluded that the alcohol aggregates can cause the formation of strong self-assembled structures that can even resist high shear forces or strains.

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Zhang, Xin, et Min Wang. « Effects of Emulsion Electrospinning Parameters on the Morphology and Structure of Core-Shell Structured PLLA Fibers ». Advanced Materials Research 410 (novembre 2011) : 386–89. http://dx.doi.org/10.4028/www.scientific.net/amr.410.386.

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Electrospinning is a popular technique for producing micro-or nanofibers for diverse applications including filtration, catalysis, sensors, cosmetics, wound dressing and tissue engineering. In some applications such as controlled drug/biomolecule delivery, core-shell structured nanofibers are desired. There are two major electrospinning processes for making core-shell structured fibers: emulsion electrospinning and coaxial electrospinning. In this study, the formation of core-shell structured fibers of poly (L-lactic acid) (PLLA) through emulsion electrospinning was investigated. To study the electrospinability of emulsions based on PLLA solutions, two solvents, pure chloroform and mixed solvent of chloroform and N,N-dimethylformamide, were used separately for making PLLA solutions. In the study of the formation of controlled release systems for biomolecules, bovine serum albumin, a model protein, was dissolved in de-ionized water to make the water phase in emulsions. In emulsion electrospinning, parameters such as applied voltage, working distance and feeding rate, were systematically investigated. The morphology, diameter and core-shell structure of emulsion electrospun fibers was studied using electron microscopies.

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Christy, Francis A., Priyanka A. Shah, Jaivik V. Shah, Bijal A. Shah et Pranav S. Shrivastav. « Conductometric studies on complexation of Ag+ cation by C-thiophene calix[4]resorcinarene in pure and mixed non-aqueous solvent systems ». Journal of Inclusion Phenomena and Macrocyclic Chemistry 83, n^o 3-4 (6 octobre 2015) : 343–53. http://dx.doi.org/10.1007/s10847-015-0570-3.

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Przybyłek, Maciej, Tomasz Jeliński, Magdalena Mianowana, Kinga Misiak et Piotr Cysewski. « Exploring the Solubility Limits of Edaravone in Neat Solvents and Binary Mixtures : Experimental and Machine Learning Study ». Molecules 28, n^o 19 (29 septembre 2023) : 6877. http://dx.doi.org/10.3390/molecules28196877.

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This study explores the edaravone solubility space encompassing both neat and binary dissolution media. Efforts were made to reveal the inherent concentration limits of common pure and mixed solvents. For this purpose, the published solubility data of the title drug were scrupulously inspected and cured, which made the dataset consistent and coherent. However, the lack of some important types of solvents in the collection called for an extension of the available pool of edaravone solubility data. Hence, new measurements were performed to collect edaravone solubility values in polar non-protic and diprotic media. Such an extended set of data was used in the machine learning process for tuning the parameters of regressor models and formulating the ensemble for predicting new data. In both phases, namely the model training and ensemble formulation, close attention was paid not only to minimizing the deviation of computed values from the experimental ones but also to ensuring high predictive power and accurate solubility computations for new systems. Furthermore, the environmental friendliness characteristics determined based on the common green solvent selection criteria, were included in the analysis. Our applied protocol led to the conclusion that the solubility space defined by ordinary solvents is limited, and it is unlikely to find solvents that are better suited for edaravone dissolution than those described in this manuscript. The theoretical framework presented in this study provides a precise guideline for conducting experiments, as well as saving time and resources in the pursuit of new findings.

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Gudelj, Martina, Paola Šurina, Lucija Jurko, Ante Prkić et Perica Bošković. « The Additive Influence of Propane-1,2-Diol on SDS Micellar Structure and Properties ». Molecules 26, n^o 12 (21 juin 2021) : 3773. http://dx.doi.org/10.3390/molecules26123773.

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Micellar systems are colloids with significant properties for pharmaceutical and food applications. They can be used to formulate thermodynamically stable mixtures to solubilize hydrophobic food-related substances. Furthermore, micellar formation is a complex process in which a variety of intermolecular interactions determine the course of formation and most important are the hydrophobic and hydrophilic interactions between surfactant–solvent and solvent–solvent. Glycols are organic compounds that belong to the group of alcohols. Among them, propane-1,2-diol (PG) is a substance commonly used as a food additive or ingredient in many cosmetic and hygiene products. The nature of the additive influences the micellar structure and properties of sodium dodecyl sulfate (SDS). When increasing the mass fraction of propane-1,2-diol in binary mixtures, the c.m.c. values decrease because propane-1,2-diol is a polar solvent, which gives it the ability to form hydrogen bonds, decreasing the cohesivity of water and reducing the dielectric constant of the aqueous phase. The values of ΔGm0 are negative in all mixed solvents according to the reduction in solvophobic interactions and increase in electrostatic interaction. With the rising concentration of cosolvent, the equilibrium between cosolvent in bulk solution and in the formed micelles is on the side of micelles, leading to the formation of micelles at a lower concentration with a small change in micellar size. According to the 1H NMR, with the addition of propylene glycol, there is a slight shift of SDS peaks towards lower ppm regions in comparison to the D2O peak. The shift is more evident with the increase in the amount of added propane-1,2-diol in comparison to the NMR spectra of pure SDS. Addition of propane-1,2-diol causes the upfield shift of the protons associated with hydrophilic groups, causing the shielding effect. This signifies that the alcohol is linked with the polar head groups of SDS due to its proximity to the SDS molecules.

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Bao, Shuqin, Ningning Sun, Wei Sun, Peng Zhou, Rensong Wang, Chen Chen, Fu Zhu, Yonghong Hu et Wenge Yang. « Determination and analysis of solubility of 5-bromo-7-azaindole in pure and mixed solvent systems at different temperatures (T = 278.15–323.15 K) ». Journal of Molecular Liquids 367 (décembre 2022) : 120476. http://dx.doi.org/10.1016/j.molliq.2022.120476.

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Chen, Xiaofeng, Xiaofang Gong, Juan Xu, Peng Li, Huiping Wang et Lifeng Ning. « Measurement and Correlation of the Solubility of Etonogestrel in Ten Pure and Binary Mixed Solvent Systems at Temperatures from 273.15 to 323.15 K ». Journal of Chemical & ; Engineering Data 65, n^o 6 (11 mai 2020) : 3190–202. http://dx.doi.org/10.1021/acs.jced.0c00201.

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Alam, Md Sayem, Baskar Ashokkumar et A. Mohammed Siddiq. « The density, dynamic viscosity and kinematic viscosity of protic and aprotic polar solvent (pure and mixed) systems : An experimental and theoretical insight of thermophysical properties ». Journal of Molecular Liquids 281 (mai 2019) : 584–97. http://dx.doi.org/10.1016/j.molliq.2019.02.097.

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Friess, Karel, Pavel Izák, Magda Kárászová, Mariia Pasichnyk, Marek Lanč, Daria Nikolaeva, Patricia Luis et Johannes Carolus Jansen. « A Review on Ionic Liquid Gas Separation Membranes ». Membranes 11, n^o 2 (30 janvier 2021) : 97. http://dx.doi.org/10.3390/membranes11020097.

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Ionic liquids have attracted the attention of the industry and research community as versatile solvents with unique properties, such as ionic conductivity, low volatility, high solubility of gases and vapors, thermal stability, and the possibility to combine anions and cations to yield an almost endless list of different structures. These features open perspectives for numerous applications, such as the reaction medium for chemical synthesis, electrolytes for batteries, solvent for gas sorption processes, and also membranes for gas separation. In the search for better-performing membrane materials and membranes for gas and vapor separation, ionic liquids have been investigated extensively in the last decade and a half. This review gives a complete overview of the main developments in the field of ionic liquid membranes since their first introduction. It covers all different materials, membrane types, their preparation, pure and mixed gas transport properties, and examples of potential gas separation applications. Special systems will also be discussed, including facilitated transport membranes and mixed matrix membranes. The main strengths and weaknesses of the different membrane types will be discussed, subdividing them into supported ionic liquid membranes (SILMs), poly(ionic liquids) or polymerized ionic liquids (PILs), polymer/ionic liquid blends (physically or chemically cross-linked ‘ion-gels’), and PIL/IL blends. Since membrane processes are advancing as an energy-efficient alternative to traditional separation processes, having shown promising results for complex new separation challenges like carbon capture as well, they may be the key to developing a more sustainable future society. In this light, this review presents the state-of-the-art of ionic liquid membranes, to analyze their potential in the gas separation processes of the future.

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Garbiec, Ewa, Natalia Rosiak, Ewa Tykarska, Przemysław Zalewski et Judyta Cielecka-Piontek. « Sinapic Acid Co-Amorphous Systems with Amino Acids for Improved Solubility and Antioxidant Activity ». International Journal of Molecular Sciences 24, n^o 6 (14 mars 2023) : 5533. http://dx.doi.org/10.3390/ijms24065533.

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The objective of this study was to obtain co-amorphous systems of poorly soluble sinapic acid using amino acids as co-formers. In order to assess the probability of the interaction of amino acids, namely, arginine, histidine, lysine, tryptophan, and proline, selected as co-formers in the amorphization of sinapic acid, in silico studies were carried out. Sinapic acid systems with amino acids in a molar ratio of 1:1 and 1:2 were obtained using ball milling, solvent evaporation, and freeze drying techniques. X-ray powder diffraction results confirmed the loss of crystallinity of sinapic acid and lysine, regardless of the amorphization technique used, while remaining co-formers produced mixed results. Fourier-transform infrared spectroscopy analyses revealed that the co-amorphous sinapic acid systems were stabilized through the creation of intermolecular interactions, particularly hydrogen bonds, and the potential formation of salt. Lysine was selected as the most appropriate co-former to obtain co-amorphous systems of sinapic acid, which inhibited the recrystallization of sinapic acid for a period of six weeks in 30 °C and 50 °C. Obtained co-amorphous systems demonstrated an enhancement in dissolution rate over pure sinapic acid. A solubility study revealed a 12.9-fold improvement in sinapic acid solubility after introducing it into the co-amorphous systems. Moreover, a 2.2-fold and 1.3-fold improvement in antioxidant activity of sinapic acid was observed with respect to the ability to neutralize the 2,2-diphenyl-1-picrylhydrazyl radical and to reduce copper ions, respectively.

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Villanueva-Bermejo, David, Guillermo Reglero, Roumiana P. Stateva et Tiziana Fornari. « Solubility of Bioactive Substances in Ethyl Lactate + Water Mixtures : Ferulic Acid and Caffeine ». Open Chemical Engineering Journal 10, n^o 1 (8 avril 2016) : 50–58. http://dx.doi.org/10.2174/1874123101610010050.

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The solubility of ferulic acid in ethyl lactate + water mixtures was measured at ambient temperature and pressure, and reported for the first time in this work. It was demonstrated that the acid solubility in the respective mixed solvents was considerably higher than in either pure ethyl lactate or water. Similar behavior pattern was recently reported by the authors for the solubility of caffeine in ethyl lactate + water mixtures. UNIQUAC and modified UNIFAC (Dortmund) were applied to represent the solubility of ferulic acid and caffeine in the mixed solvents and their capabilities to describe adequately the cosolvent effect observed was tested and compared. The results obtained demonstrated that the UNIQUAC model provided excellent correlation of the experimental data for both systems. The UNIFAC model, on the other hand, was applied in a completely predictive manner and produced very good results for ferulic acid solubility and just qualitative predictions for caffeine.

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Serhieieva, Yevheniia, Anton Zakharov et Sergey Kiyko. « Peculiarities of solvatochromism of 4-[[(2,4-dinitrophenyl)methylene]imino-2,6-diphenyl]phenol and Reichardt’s dye. DFT calculations ». Kharkov University Bulletin Chemical Series, n^o 38 (14 juin 2022) : 23–30. http://dx.doi.org/10.26565/2220-637x-2022-38-03.

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One of the current directions of development of modern physical chemistry is the working out of sensor devices and molecular probes for the study of various properties of solutions, colloidal systems and biological objects. The latter include solvatochromic dyes, which, thanks to Reichardt's classic works, have found wide application for quantitative assessment of the solvating ability of individual and, to a lesser extent, mixed solvents of various nature. The different behavior of Reichardt and 4-[[(2,4-dinitrophenyl)methylene]imino-2,6-diphenyl]phenol dyes in pure water and mixed water-organic solvents, when their composition is changed, indicates that their electronic structure undergoes a fundamental change during the transition from the ground state to the first excited state. The aim of the work was to study and compare the HOMO and LUMO structure of the standard Reichardt betaine dye and the 4-[[(2,4-dinitrophenyl)methylene]imino-2,6-diphenyl]phenol dye using the stationary and time-dependent density functional theory (DFT). It is proved that the 4-[[(2,4-dinitrophenyl)methylene]imino-2,6-diphenyl]phenol dye has two active exchangeable solvation centers and therefore has an excellent solvation mechanism, at least in aqueous solution, compared to Reichardt dye, which should appear upon its solvation also in mixed water-organic solvents with a high water content in them.

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Jiao, Jinqing, Tao Li, Guangwen Zhang, Jing Xiong, Xuqing Lang, Xiaolong Quan, Yiwei Cheng et Yuechang Wei. « Molecular Dynamics Simulations of the Short-Chain Fluorocarbon Surfactant PFHXA and the Anionic Surfactant SDS at the Air/Water Interface ». Molecules 29, n^o 7 (3 avril 2024) : 1606. http://dx.doi.org/10.3390/molecules29071606.

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The research and development of alternatives to long-chain fluorocarbon surfactants are desperately needed because they are extremely toxic, difficult to break down, seriously harm the environment, and limit the use of conventional aqueous film-forming foam fire extinguishing agents. In this study, mixed surfactant systems containing the short-chain fluorocarbon surfactant perfluorohexanoic acid (PFHXA) and the hydrocarbon surfactant sodium dodecyl sulfate (SDS) were investigated by molecular dynamics simulation to investigate the microscopic properties at the air/water interface at different molar ratios. Some representative parameters, such as surface tension, degree of order, density distribution, radial distribution function, number of hydrogen bonds, and solvent-accessible surface area, were calculated. Molecular dynamics simulations show that compared with a single type of surfactant, mixtures of surfactants provide superior performance in improving the interfacial properties of the gas–liquid interface. A dense monolayer film is formed by the strong synergistic impact of the two surfactants. Compared to the pure SDS system, the addition of PFHXA caused SDS to be more vertically oriented at the air/water interface with a reduced tilt angle, and a more ordered structure of the mixed surfactants was observed. Hydrogen bonding between SDS headgroups and water molecules is enhanced with the increasing PFHXA. The surface activity is arranged in the following order: PFHXA/SDS = 1:1 > PFHXA/SDS = 3:1 > PFHXA/SDS = 1:3. These results indicate that a degree of synergistic relationship exists between PFHXA and SDS at the air/water interface.

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Alam, Md Sayem, Baskar Ashokkumar et A. Mohammed Siddiq. « The density, dynamic viscosity and kinematic viscosity of protic polar solvents (pure and mixed systems) studies : A theoretical insight of thermophysical properties ». Journal of Molecular Liquids 251 (février 2018) : 458–69. http://dx.doi.org/10.1016/j.molliq.2017.12.089.

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Shua'ab, Abbas Khalaf Mohammed. « Drag Reducing Flow of water in forced closed loop circulation system by using Sodium dodecyl sulfate additive ». Kufa Journal of Engineering 4, n^o 1 (30 janvier 2014) : 97–112. http://dx.doi.org/10.30572/2018/kje/411254.

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The turbulent flow friction of a water solution with a small amount of surfactant additive is dramatically reduced when compared to that of pure water. This effect offers a significant reduction in pumping power and energy consumption. Commercial implementation of drag reducing fluids have proved successful for oil pipeline transportation, district heating and cooling systems, fire fighting, sewer throughput, jet cutting, etc. The investigation was carried out on a facility with a forced closed loop for pressure drop measurements. A type of anionic surfactant (Sodium dodecyl sulfate) mixed with same weight of counter ion material (Sodium nitrate) was used as a drag reducing additive to tap water at a mass concentration ranged from 50 to 2000 ppm. Pressure drop data was collected over a 1668 mm flow pipe of carbon steel with 15.8 and 26.6 mm internal diameter and different solution flow rate (up to 8 m3/h) at constant temperature of 30 ÌŠC (ambient temperature). The paper focused on calculation of friction factor from experimental data. It was found that the friction factor values lies near Blasuis asymptote for pure solvent, while they positioned towards maximum drag reduction asymptotes when surfactant is added. A maximum drag reduction percent of about 66% was obtained by using 2000 ppm surfactant â€“ counter ion aqueous solution. Also, it was concluded that there is a critical Reynolds number equals to about 96000 not to be exceeded because any further increasing leads to decrease in drag reduction. In addition, a correlation equation was found to correlate wall shear stress as a function of bulk mean fluid velocity. This correlation equation is of value in scale up of results obtained in small laboratory equipments to larger diameter pipes and different operating conditions. Another objective was to investigate the mechanism behind a possible drag reduction.

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Kaushal, Deepika, Dilbag S. Rana, Manish Kumar, Kailash Singh, Kuldeep Singh, Suvarcha Chauhan et Ahmad Umar. « Furosemide–Cetyltrimethylammonium Bromide Interactions in Aqueous Dimethylsulfoxide Solutions : Physico–Chemical Studies ». Zeitschrift für Physikalische Chemie 233, n^o 3 (26 mars 2019) : 413–30. http://dx.doi.org/10.1515/zpch-2017-1014.

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Abstract Interaction of a cardiovascular drug, Furosemide with cetyltrimethylammonium bromide (CTAB) has been studied in aqueous solutions of Dimethylsulfoxide (DMSO) with the help of density, speed of sound and conductivity measurements over a range of temperatures 293.15–313.15 K at interval of 5 K. The interaction parameters viz. apparent molar volume, Vϕ and apparent molar isentropic compression, κs,ϕ have been enumerated from density and speed of sound data. Also, variation in the micellization behavior has been explored by calculating critical micelle concentration, CMC. It has been observed that micellization tendency of the surfactant decreases in the presence of DMSO as compared to pure aqueous system. Moreover, the CMC values shift toward lower concentration with increase in Furosemide content because of increase in hydrophobic hydration which may be to hydrophobicity of drug molecule. The dependence of CMC in mole fraction (Xcmc) values on the temperature has been analyzed in terms of thermodynamics of the system by reporting the standard thermodynamic parameters i.e. standard Gibb’s free energy $(\Delta G_m^o),$ enthalpy $(\Delta H_m^o)$ and entropy $(\Delta S_m^o)$ of micellization for CTAB in mixed solvent systems. The entropies of micellization are all positive, and they compensate the enthalpies of the process. Compensation temperature, Tc has also been evaluated from enthalpy–entropy compensation whose values lies in Lumrys range (270–300 K).

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Rub, Malik Abdul, Naved Azum, Dileep Kumar, Muhammad Nadeem Arshad, Anish Khan, Maha Moteb Alotaibi et Abdullah M. Asiri. « Investigation of Solution Behavior of Antidepressant Imipramine Hydrochloride Drug and Non-Ionic Surfactant Mixture : Experimental and Theoretical Study ». Polymers 13, n^o 22 (21 novembre 2021) : 4025. http://dx.doi.org/10.3390/polym13224025.

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In this paper, the interaction of imipramine hydrochloride (IMP, antidepressant drug) and a non-ionic surfactant Triton X-100 (TX-100) mixture in five different ratios through the tensiometric method in different solvents (aqueous/0.050 mol·kg−1 aqueous NaCl/0.250 mol·kg−1 aqueous urea (U)) were examined thoroughly at a temperature of 298 K. UV–Visible studies in an aqueous system of IMP + TX-100 mixtures were also investigated and discussed in detail. The pure (IMP and TX-100) along with the mixtures’ critical micelle concentration (cmc) were assessed by a tensiometric technique. The obtained deviation of the mixtures’ cmc values from their ideal values revealed the nonideal behavior of IMP + TX-100 mixtures amongst IMP and TX-100. Compared to aqueous systems, in the presence of aqueous NaCl, several changes in micelles/mixed micelles occurred, and hence a synergism/attractive interaction amongst components was found increased while in the existence of U, the synergism/attractive interaction between them decreased. The evaluated interaction parameter (βRb) value of mixed micelles showed the attractive or synergism between the IMP and TX-100. Various evaluated thermodynamic parameters in an aqueous system showed that the mixed micellization of the IMP + TX-100 mixture was an entropically spontaneous phenomenon, although the existence of salt in all studied systems can somewhat increase the spontaneity of the micellization process and in the aqueous U system, the spontaneity of the micellization process decreased. In an aqueous system, the interaction between IMP and TX-100 was also confirmed by UV–Visible study.

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Gao, Ming, Yuanlu Zhu, Jiangyi Yan, Weixing Wu et Beifu Wang. « Micromechanism Study of Molecular Compatibility of PVDF/PEI Blend Membrane ». Membranes 12, n^o 8 (21 août 2022) : 809. http://dx.doi.org/10.3390/membranes12080809.

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In this paper, the compatibility of polyetherimide (PEI) with different contents as a high-performance copolymer and polyvinylidene fluoride (PVDF) was studied, and 5%–20% PEI was prepared by the non-solvent-induced phase inversion method. The compatibility of PVDF and PEI was evaluated by analyzing the physical structure and properties of the blend membrane, the microstructure, the glass transition temperature Tg, the enthalpy, and the mechanism of the polymer blend enthalpy change. The results show that the blend membranes have -NH and C=O-N binding energies at X-ray photoelectron spectroscopy (XPS), which preliminarily proves that fluorine–amine bonds are formed between the polymers, and new spectra appeared by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) peaks, which further proves that the two have the formation of fluorine–amine bonds, the Tg and enthalpy of the mixed membrane was increased, and a scanning electron microscope (SEM) observed that the membrane pores changed from finger-like pores to sponge-like macropores. When the content of PEI is 15%, the performance of the blended membrane is the best, the water contact angle increases to 58.5°, the porosity increases to 17.33%, the maximum force increases to 8.04 N, and the elongation at break decreases to 24.26%, the pure water flux is 1870.292 L/m2·h, and the oil rejection is 87%. In addition, the enthalpy change of polymer blending further proves that PEI and PVDF are compatible systems and have a good performance improvement for PVDF.

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Actis, Arianna, Francesca Sacchi, Christos Takidis, Maria Cristina Paganini et Erik Cerrato. « Changes in Structural, Morphological and Optical Features of Differently Synthetized C3N4-ZnO Heterostructures : An Experimental Approach ». Inorganics 10, n^o 8 (16 août 2022) : 119. http://dx.doi.org/10.3390/inorganics10080119.

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C3N4 is an innovative material that has had huge success as a photocatalyst in recent years. More recently, it has been coupled to robust metal oxides to obtain more stable materials. This work is focused on the different synthesis techniques used to prepare bare C3N4 and combined C3N4/ZnO mixed systems. Different precursors, such as pure melamine and cyanuric acid-based supramolecular complexes, were employed for the preparation of the C3N4 material. Moreover, different solvents were also used, demonstrating that the use of water leads to the formation of a more stable heterojunction. Structural (XRD), morphological (FESEM) and optical (UV-vis) measurements underlined the role of the precursors used in the preparation of the materials. A clear trend can be extrapolated from this experimental approach involving different intimate contacts between the two C3N4 and ZnO phases, strictly connected to the particular preparation method adopted. The use of the supramolecular complexes for the preparation of C3N4 leads to a tighter association between the two phases at the heterojunction, resulting in much higher visible light harvesting (connected to lower band gap values).

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Acree, William E. « Comments on “The density, dynamic viscosity and kinematic viscosity of protic and aprotic polar solvents (pure and mixed) systems : An experimental and theoretical insight of thermophysical properties” ». Journal of Molecular Liquids 283 (juin 2019) : 299–301. http://dx.doi.org/10.1016/j.molliq.2019.03.081.

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Shenoy, Sulakshana, Mohsen M. Farahat, Chitiphon Chuaicham, Karthikeyan Sekar, Boopathy Ramasamy et Keiko Sasaki. « Mixed-Phase Fe2O3 Derived from Natural Hematite Ores/C3N4 Z-Scheme Photocatalyst for Ofloxacin Removal ». Catalysts 13, n^o 5 (23 avril 2023) : 792. http://dx.doi.org/10.3390/catal13050792.

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Abatement of pharmaceutical pollutants from aquatic systems is crucial but remains a challenge. Semiconductor photocatalysis has emerged as an eco-friendly technique that utilizes renewable solar energy to address environmental issues. Naturally occurring and earth abundant hematite (Fe2O3) ores can be incorporated as a suitable component of a photocatalyst. Herein, Brazilian hematite was partially phase transformed into heterophase (consisting of α/γ-Fe2O3) by a simple single-stage heat treatment procedure. The method of synthesis was simple and economical, requiring neither solvents nor concentrated acids. The existence of α/γ-phases in the produced Fe2O3 (FO) was confirmed by X-ray diffraction analysis. After the phase transformation process, the local structure surrounding the Fe atoms was varied as evidenced from X-ray absorption spectroscopy. Given its low toxicity, narrow bandgap, and chemical stability, FO was further combined with g-C3N4 (CN) to form composites. The optical properties of the synthesized CNFO composites confirmed that the visible light harvesting ability of CN was enhanced after combining with FO. The CN sheets were grown uniformly over the surface of FO as evidenced from scanning electron microscopy. The prepared composites could degrade an aqueous solution of ofloxacin (OFX, 10 ppm) under visible light with remarkable efficacy. The performance of CNFO-5% was 4.8 times higher when compared to pure CN. The initial rate constant value for the photocatalytic degradation of OFX by CNFO-5% was 0.1271 min−1. The catalyst was stable even after five repeated cycles of photodegradation. The photoluminescence spectra and electrochemical measurements confirmed the efficient separation and transfer of the photogenerated charges across their interface. The investigations on different scavengers demonstrated that superoxide anion radicals and holes played a significant role in the degradation of OFX. The mechanism for the charge transfer was proposed to be a Z-scheme heterojunction. These results point to the potential of using inexpensive, abundant, and recyclable natural hematite ores as state-of-the-art photocatalysts for the elimination of pharmaceuticals in wastewater.

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Marín, Sabrina, Mayra Cortés, Mauricio Acosta, Karla Delgado, Camila Escuti, Diego Ayma et Cecilia Demergasso. « From Laboratory towards Industrial Operation : Biomarkers for Acidophilic Metabolic Activity in Bioleaching Systems ». Genes 12, n^o 4 (25 mars 2021) : 474. http://dx.doi.org/10.3390/genes12040474.

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In the actual mining scenario, copper bioleaching, mainly raw mined material known as run-of-mine (ROM) copper bioleaching, is the best alternative for the treatment of marginal resources that are not currently considered part of the profitable reserves because of the cost associated with leading technologies in copper extraction. It is foreseen that bioleaching will play a complementary role in either concentration—as it does in Minera Escondida Ltd. (MEL)—or chloride main leaching plants. In that way, it will be possible to maximize mines with installed solvent-extraction and electrowinning capacities that have not been operative since the depletion of their oxide ores. One of the main obstacles for widening bioleaching technology applications is the lack of knowledge about the key events and the attributes of the technology’s critical events at the industrial level and mainly in ROM copper bioleaching industrial operations. It is relevant to assess the bed environment where the bacteria–mineral interaction occurs to learn about the limiting factors determining the leaching rate. Thus, due to inability to accurately determine in-situ key variables, their indirect assessment was evaluated by quantifying microbial metabolic-associated responses. Several candidate marker genes were selected to represent the predominant components of the microbial community inhabiting the industrial heap and the metabolisms involved in microbial responses to changes in the heap environment that affect the process performance. The microbial community’s predominant components were Acidithiobacillus ferrooxidans, At. thiooxidans, Leptospirillum ferriphilum, and Sulfobacillus sp. Oxygen reduction, CO2 and N2 fixation/uptake, iron and sulfur oxidation, and response to osmotic stress were the metabolisms selected regarding research results previously reported in the system. After that, qPCR primers for each candidate gene were designed and validated. The expression profile of the selected genes vs. environmental key variables in pure cultures, column-leaching tests, and the industrial bioleaching heap was defined. We presented the results obtained from the industrial validation of the marker genes selected for assessing CO2 and N2 availability, osmotic stress response, as well as ferrous iron and sulfur oxidation activity in the bioleaching heap process of MEL. We demonstrated that molecular markers are useful for assessing limiting factors like nutrients and air supply, and the impact of the quality of recycled solutions. We also learned about the attributes of variables like CO2, ammonium, and sulfate levels that affect the industrial ROM-scale operation.

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Pukhovskaya, Svetlana G., Yulia B. Ivanova, Dmitry A. Erzunov, Aleksander S. Semeykin et Sergei A. Syrbu. « SYNTHESIS, COORDINATION AND ACID-BASE PROPERTIES OF MESO-DINITROSUBSTITUTED DERIVATIVES OF 5,15-DIPHENYL-β-OCTAALKYLPORPHINE ». IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 61, n^o 6 (6 juin 2018) : 17. http://dx.doi.org/10.6060/tcct.20186106.5655.

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Presented work shows results of synthesis and spectrophotometric researches on properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphyrin nitroderivatives in comparison with 2,8,12,18,3,7,13,17-octaethylporphyrin and 2,3,7,8,12,13,17,18-octaethyl-5,15-dinitroporphyrin. The method of spectrophotometric titration with perchloric acid (for determining the basicity constant) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) was used in order to study the acid-base properties of porphyrins, namely to determine the acidity constant. The spectral characteristics of the ionized forms of 5,15-dinitro-10,20-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporfin-F (I) and 5,15-dinitro-10,20-bis(4-nitrophenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetraethylporphyrin (II) and the corresponding total constants of the acidic (pKa (I) = 6.00 and pKa (II) = 5.27) and the basic (pKb (I) = 19.78 and pKb (II) = 19.83) ionization were provided. The reaction of complexation of porphyrins with zinc acetate was studied by spectrophotometric method in pure acetonitrile and in mixed AN + DBU solvent. The influence of the degree of deformation of the tetrapyrrole macroring, the electronic effects of substituents and the acidity of the medium on the coordination and acid-base properties of porphyrins was analyzed. It was shown that the reactions of formation of metalloporphyrins with anionic porphyrin forms proceed with much higher rates compared to molecular ones, that is accompanied with a decrease in the energy parameters of the reaction. This is evidently due to the absence of energy costs for the deformation and cleaving N-H bonds of the reaction center, as well as the stronger polarization of the molecule, and as a consequence, the higher degree of solvation of anionic forms of porphyrins in the transition state. Thus, the determination of the conditions for the existence of dianionic forms of porphyrins gives grounds for the development of new sensor systems for the recognition and determination of the concentration of metal cations in liquid media due to a sharp increase in the rate of formation of metalloporphyrins in the presence of an organic base.Forcitation:Pukhovskaya S.G., Ivanova Yu.B., Erzunov D.A., Semeykin A.S., Syrbu S.A. Synthesis, coordination and acid-base properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphine. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 17-28

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Laesecke, Arno. « Comment on The density, dynamic viscosity and kinematic viscosity of protic and aprotic polar solvent (pure and mixed) systems : An experimental and theoretical insight of thermophysical properties by M. S. Alam, B. Ashokkumar and A. M. Siddiq, J. Mol. Liquids, 281(2019), 584–597 ». Journal of Molecular Liquids 294 (novembre 2019) : 111642. http://dx.doi.org/10.1016/j.molliq.2019.111642.

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El Seoud, Omar A. « Solvation in pure and mixed solvents : Some recent developments ». Pure and Applied Chemistry 79, n^o 6 (1 janvier 2007) : 1135–51. http://dx.doi.org/10.1351/pac200779061135.

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The effect of solvents on the spectra, absorption, or emission of substances is called solvatochromism; it is due to solute/solvent nonspecific and specific interactions, including dipole/dipole, dipole-induced/dipole, dispersion interactions, and hydrogen bonding. Thermo-solvatochromism refers to the effect of temperature on solvatochromism. The molecular structure of certain substances, polarity probes, make them particularly sensitive to these interactions; their solutions in different solvents have distinct and vivid colors. The study of both phenomena sheds light on the relative importance of the solvation mechanisms. This account focuses on recent developments in solvation in pure and binary solvent mixtures. The former has been quantitatively analyzed in terms of a multiparameter equation, modified to include the lipophilicity of the solvent. Solvation in binary solvent mixtures is complex because of the phenomenon of "preferential solvation" of the probe by one component of the mixture. A recently introduced solvent exchange model allows calculation of the composition of the probe solvation shell, relative to that of bulk medium. This model is based on the presence of the organic solvent (S), water (W), and a 1:1 hydrogen-bonded species (S-W). Solvation by the latter is more efficient than by its precursor solvents, due to probe/solvent hydrogen-bonding and hydrophobic interactions. Dimethylsulfoxide (DMSO) is an exception, because the strong DMSO/W interactions probably deactivate the latter species toward solvation. The relevance of the results obtained to kinetics of reactions is briefly discussed by addressing temperature-induced desolvation of the species involved (reactants and activated complexes) and the complex dependence of kinetic data (observed rate constants and activation parameters) in binary solvent mixtures on medium composition.

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Bhattarai, Ajaya, Kavita Pathak et Bikash Dev. « Micellization behavior of mixed surfactants in pure water and methanol-water mixed solvent media by density methods ». BIBECHANA 13 (3 décembre 2015) : 114–20. http://dx.doi.org/10.3126/bibechana.v13i0.13887.

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The properties of anionic-rich and cationic-rich mixtures of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylsulfate (SDS) in pure water and methanol-water mixed solvent media were studied using density measurements at room temperature. The results showed that density increases with increasing concentration of surfactant mixture over the entire concentration range investigated in pure water and in the given mixed solvent media and which are found to decrease with an increase in the volume fraction of methanol in the solvent composition. The critical micelle concentration increases with the increase in volume fraction of methanol for both the anionic-rich (SDS-DTAB) and cationic-rich (DTAB-SDS) systems.BIBECHANA 13 (2016) 114-120

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Maitra, Angshuman, et Sanjib Bagchi. « Study of solute–solvent and solvent–solvent interactions in pure and mixed binary solvents ». Journal of Molecular Liquids 137, n^o 1-3 (janvier 2008) : 131–37. http://dx.doi.org/10.1016/j.molliq.2007.06.002.

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