Impact of salts on the phase separation and thermodynamic properties of mixed nonionic surfactants in absence/attendance of polyvinyl alcohol

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Md Ackas Ali ◽  
Md. Ruhul Amin ◽  
Shamim Mahbub ◽  
Md. Delwar Hossen ◽  
Md. Anamul Hoque ◽  
...  
Keyword(s):  
Free Energy ◽  
Polyvinyl Alcohol ◽  
Aqueous Medium ◽  
Standard Free Energy ◽  
Tween 80 ◽  
Aqueous System ◽  
Standard Entropy ◽  
Thermodynamic Variables ◽  
Delta G ◽  
Energy Of Transfer

Abstract Mixed surfactant systems are used in different applied fields like pharmaceutical formulation rather than single surfactant. Therefore, the determination of the clouding nature of the triton X-100 (TX-100) + Tween 80 (TW-80) mixture was carried out in H2O and polyvinyl alcohol (PVA). In the occurrence of PVA, the cloud point (CP) values of TX-100 initially enhance with enhancing the concentration of PVA and tend to decrease after a certain concentration. For different ratios of TX-100 and TW-80 mixture having the same concentration of both solutions, CP values increase through the decreasing ratios of TX-100 with/without PVA. In the presence of polymer, at higher ratios of TX-100 than TW-80, the CP values are higher in magnitudes in comparison to the aqueous medium but at lower ratios of TX-100, the value of CP are lower in magnitudes in comparison to the aqueous system. The CP values of the TX-100 + TW-80 mixture in the salt system are lower in magnitudes than the aqueous medium in both the absence/presence of PVA. However, a reduction of CP values was obtained to a large extent for Na2SO4 over NaCl in the case of lower volume ratios of TX-100. Various thermodynamic variables (standard free energy ( Δ G c o ${\Delta}{G}_{c}^{o}$ ), standard enthalpy ( Δ H c o ${\Delta}{H}_{c}^{o}$ ), standard entropy ( Δ S c o ${\Delta}{S}_{c}^{o}$ ) change, thermodynamic parameters of transfer (free energy of transfer ( Δ G c , t o ${\Delta}{G}_{c,t}^{o}$ ), and transfer of enthalpies ( Δ H c , t o ${\Delta}{H}_{c,t}^{o}$ )) of phase transition) were also determined.

scholarly journals HYDROPHOBIC EFFECTS IN WATER AND WATER/UREA SOLUTIONS A COMPARISON

1994 ◽  
Vol 2 (2) ◽  
pp. 71-82
Author(s):  
E. A. Lissi ◽  
E. B. Abuin
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Alkyl Chain ◽  
Standard Free Energy ◽  
The Other ◽  
Standard Entropy ◽  
Simple Description ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

The partition of several n-alkanols, from methanol to n-nonanol, between n-hexane and water and between n-hexane and water containing 20 % (w/v) urea has been measured at temperatures ranging from 0 °C to 60 °C. The standard free energy of transfer from water to the urea-containing solution decreases with the length of the alkyl chain, being positive for the small alcohols and negative for the higher alkanols. The same tendency is observed upon all the temperature range considered. On the other hand, the standard entropy of transfer from water to the urea-containing solution increases with the length of the alkyl chain of the alkanol. These results are compatible with a simple description of the urea effect in terms of increasing the entropy of dissolution of the hydrophobic alkyl chain in the aqueous solution.

The enols of acetic acid and methyl acetate

1995 ◽  
Vol 73 (9) ◽  
pp. 1395-1398 ◽  
Author(s):  
J. Peter Guthrie ◽  
Zhi Liu
Keyword(s):  
Free Energy ◽  
Acetic Acid ◽  
Methyl Acetate ◽  
Heat Of Formation ◽  
Standard Entropy ◽  
Free Energies ◽  
Average Value ◽  
Boiling Points ◽  
Free Energy Of Formation ◽  
Energy Of Transfer

We have determined the heat of formation of 1,1-dimethoxyethene, ΔHf(l) = −75.56 ± 0.87 kcal mol−1, by measuring the heat of hydrolysis. The heat of vaporization, 8.47 ± 0.10 kcal mol−1, was estimated from the boiling points at various pressures. The standard entropy of gaseous 1,1-dimethoxyethene, 82.02 ± 2. cal deg−1 mol−1, was calculated using frequencies obtained by MO calculations at the 6-31G** level. The free energy of transfer, 1.02 ± 1, was estimated by additivity with allowance for a distant polar interaction. Thus the free energy of formation in aqueous solution, ΔGf(aq) = −37.07 ± 1.48 kcal mol−1, could be calculated. The free energies of hydrolysis for enol ethers appear to be insensitive to structure; we used an average value and so calculated the values of the free energies of formation of the enols of acetic acid and methyl acetate, −67.90 ± 1.67 and −52.48 ± 1.53 kcal mol−1, respectively. These values are in good agreement with other recent evaluations. This method should be applicable to related enols. Keywords: enols, thermodynamics, heat of formation, entropy, ketene acetal.

Interaction of cationic surfactant with acid yellow dye in absence/presence of organic and inorganic additives: conductivity and dye solubilization methods

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Md. Ariful Haque ◽  
Shamim Mahbub ◽  
Mohammad Majibur Rahman ◽  
Md. Anamul Hoque ◽  
Dileep Kumar ◽  
...  
Keyword(s):  
Free Energy ◽  
Cationic Surfactant ◽  
Cetyltrimethylammonium Bromide ◽  
Micelle Formation ◽  
Aqueous System ◽  
Nacl Solution ◽  
Solubilization Capacity ◽  
Delta G ◽  
Free Energy Of Micellization ◽  
Dye Solubilization

Abstract In the present study, the conductometric and dye-solubilization techniques have been utilized to investigate the interaction between an anionic dye (acid yellow 23 [AY]) and a cationic surfactant (cetyltrimethylammonium bromide [CTAB]) in presence of organic (ethanol)/inorganic (NaCl) additives. From the conductometric method, two critical micelle concentrations (cmc) were found for AY + CTAB mixture in an aqueous system and the cmc values were found to undergo a change with the variation of AY concentrations. The cmc values of AY + CTAB systems were observed higher in the alcoholic medium, while the same was found to be lower in the NaCl solutions. The change in cmc of AY + CTAB systems shows an U-like curve with an increase of temperature. The negative free energy of micellization ( Δ G m o ${\Delta}{G}_{m}^{o}$ ) for the AY + CTAB systems has indicated a spontaneous micelle formation in all of the cases studied. The enthalpy ( Δ H m o ${\Delta}{H}_{m}^{o}$ ), as well as the entropy of micellization ( Δ S m o ${\Delta}{S}_{m}^{o}$ ) for the AY + CTAB systems, were assessed and discussed with proper reasoning. Additionally, the enthalpy-entropy compensation parameters were also investigated and illustrated. The solubility of AY and C D was observed to rise linearly with an increase in the concentration of CTAB/NaCl solution. The solubilization capacity (χ) of AY, the molar partition coefficient (K M) amongst the micellar and the aqueous phase, and free energy of solubilization ( Δ G S o ${\Delta}{G}_{S}^{o}$ ) were evaluated and discussed in detail. The former parameters undergo an increase with an increase of NaCl concentrations.

Standard thermodynamic transfer functions from water to water + acetone mixtures for a n-nonylcarbon chain attached to different ionic groups

1978 ◽  
Vol 56 (23) ◽  
pp. 2940-2946 ◽  
Author(s):  
Raymond Bury ◽  
Claude Treiner
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Standard Enthalpy ◽  
Transfer Functions ◽  
Mixed Solvents ◽  
Standard Entropy ◽  
Standard Gibbs Free Energy ◽  
Ionic Groups ◽  
Solvent Molecules ◽  
Energy Of Transfer

The standard enthalpy of transfer of trimethyldecylammonium bromide, tetramethylammonium bromide, methyl and decylsodium sulfate have been determined from water to water + acetone mixtures from calorimetric measurements at 298.15 K. The standard entropy function has been calculated using standard Gibbs free energy of transfer data for the same compounds. It is shown that the standard enthalpy and entropy of transfer of a n-nonylhydrocarbon chain attached to the sulfate or to the trimethylammonium groups are quite different whereas the standard Gibbs free energy functions are practically equal in the mixed solvents. It is concluded that the sign of the charge on the ionic groups is responsible for this behaviour and that the influence of this effect extends to a large number of solvent molecules. It is suggested that a similar effect may contribute to the standard enthalpy of so called reference ions: e.g. tetraphenylboron ion casting some doubt on the reliability of these extrathermodynamic approaches at least in mixed solvents, as far as the standard enthalpy function is concerned.

scholarly journals Standard Free Energy of Transfer of Potassium Chloride from Light to Heavy Water from Solubilities of Sparingly Soluble Salts.

1971 ◽  
Vol 25 ◽  
pp. 361-363 ◽  
Author(s):  
Pentti Salomaa ◽  
Marja Mattsén ◽  
Hans Sievertsson ◽  
Inger Skånberg ◽  
Karl-Gustav Svensson ◽  
...  
Keyword(s):  
Free Energy ◽  
Potassium Chloride ◽  
Heavy Water ◽  
Standard Free Energy ◽  
Soluble Salts ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

Dielectric Measurements and Molecular Structure. Thermodynamic Parameters in Conformational Equilibria of α-Diazoketones

1979 ◽  
Vol 34 (11) ◽  
pp. 1530-1534
Author(s):  
Salvatore Sorriso
Keyword(s):  
Molecular Structure ◽  
Free Energy ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Standard Free Energy ◽  
Standard Entropy ◽  
Dielectric Measurements ◽  
Electric Dipole Moments ◽  
Conformational Equilibria ◽  
Cis Isomer

Abstract The electric dipole moments of acetyldiazomethane (MeCOCHN2) and 1-acetyl-1-diazo-ethane (MeCOMeN2) between 10 and 70 °C have been measured. Using appropriate group and bond moments, the concentrations of the two rotamers present in each have been calculated and, hence, the equilibrium constant for the cis ⇆ trans equilibrium at the various temperatures.The change in standard enthalpy (⊿H°), standard free energy (⊿G°) and standard entropy (⊿S°) are reported for the conversion of one mole of cis isomer to trans isomer.

Thermodynamic Properties of Aqueous Organic Solutes in Relation to Their Structure. Part I. Free Energy of Transfer from H2O to D2O for a Series of Isomeric Ketones

1973 ◽  
Vol 51 (18) ◽  
pp. 3051-3061 ◽  
Author(s):  
Carmel Jolicoeur ◽  
Ghislain Lacroix
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Scaled Particle Theory ◽  
Cavity Formation ◽  
Degree Of Branching ◽  
Structural Part ◽  
Hydrocarbon Chains ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Heats Of Transfer

The solubilities of 18 decanones have been measured in H2O and D2O at 25 °C from their u.v. absorption spectra. The data were used to calculate ΔGt0, the standard free energy of transfer of these solutes from H2O to D2O ΔGt0 was found negative for the saturated ketones, but positive for most of the unsaturated and polycyclic isomers. A rough correlation was observed between ΔGt0 and the degree of branching in the hydrocarbon chains of the ketones: ΔGt0 increases with the degree of branching. From the temperature dependence of ΔGt0 obtained at 10, 25, and 40 °C, heats of transfer ΔHt0 were determined for typical ketones, namely 2-decanone and adamantanone. ΔHt0 was found as −2.1 kcal mol−1 for 2-decanone and ~0 ± 0.5 kcal mol−1 for adamantanone.The results are discussed in terms of two main contributions: (1) an isotope effect in the free energy of cavity formation and (2) perturbation of solvent structure by the solutes, differing in H2O and D2O. Using the scaled-particle theory to evaluate the former, the variations in the observed ΔGt0 are assigned to the structural part of ΔGt0.

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