Measurements of the (p, ρ,T) properties and virial coefficients of pure water, methane,n-hexane,n-octane, benzene, and of their aqueous mixtures in the supercritical region

1996 ◽  
Vol 28 (9) ◽  
pp. 1037-1057 ◽  
Author(s):  
I.M. Abdulagatov ◽  
A.R. Bazaev ◽  
R.K. Gasanov ◽  
A.E. Ramazanova
Keyword(s):  
Pure Water ◽  
Virial Coefficients ◽  
Aqueous Mixtures ◽  
Supercritical Region

Temperature Dependent Solubility of Benzoic Acid in Aqueous Phase and Aqueous Mixtures of Aliphatic Alcohols

2020 ◽  
Vol 234 (11-12) ◽  
pp. 1771-1787
Author(s):  
Sayyar Muhammad ◽  
Sofia Sanam ◽  
Hamayun Khan ◽  
Akhtar Muhammad ◽  
Sabiha Sultana
Keyword(s):  
Benzoic Acid ◽  
Aqueous Phase ◽  
Linear Trend ◽  
Pure Water ◽  
Binary Solvents ◽  
Aqueous Mixtures ◽  
Analytical Technique ◽  
Temperature Range ◽  
Acid Solubility ◽  
Ethanol In Water

AbstractThe benzoic acid solubility in aqueous phase and in various aqueous mixtures of methanol, ethanol and 2-propanol was determined at temperatures ranging from 303 to 333 K by an analytical technique. The results showed that the solubility of the acid in alcohols-water binary mixtures is high as compared to pure aqueous phase. The addition of alcohols to water favors the dissolution of benzoic acid which increases further with the increase in alcohols content of water within the investigated temperature range. The benzoic acid solubility in water alone and aqueous mixtures of the selected alcohols was in the order of; 2-propanol in water > ethanol in water > methanol in water > pure water. It is also observed that within the investigated temperature range, the acid solubility increases with rise in temperature in both the aqueous phase and alcohols-water binary solvents. The logarithm of the mole fraction of the acid’s solubility also showed a linear trend against the temperature. The experimental results obtained in the current study were compared with the reported literature for the studied acid and other organic acids in various solvents and showing a good agreement. The study will have implications in the processes involving separation, crystallization and pharmaceutical formulation in various industries.

Aqueous Mixtures with Nonpolar Gases at High Pressures and Supercritical Temperatures

1983 ◽  
Vol 22 ◽  
Author(s):  
E.U. Franck
Keyword(s):  
Dielectric Constant ◽  
High Pressures ◽  
Pure Water ◽  
Boundary Surface ◽  
Type Equation ◽  
Critical Curve ◽  
Aqueous Mixtures ◽  
Two Phase ◽  
Slow Increase ◽  
Critical Curves

ABSTRACTPTx-phase diagrams and critical curves for binary aqueous systems are briefly discussed. New results of the two-phase boundary surface and the critical curve for the water-nitrogen system to 2500 bar and 400°C are presented as isotherms in the Px-plane. A new extended Carnahan-Starling and squarewell type equation permits calculations of spinodal isopleths of the water-methane system and a prediction of the critical curve. - Excess volumes of supercritical benzene-water mixtures are given as functions of composition and pressure. Excess Gibbs energies and activity coefficients are derived. For the same system the static dielectric constant was measured between 300 and 400 °C in the homogeneous supercritical fluid for all concentrations. At 400 °C and 2000 bar the dielectric constant of pure water is 20 and decreases steeply with the addition of benzene. Addition of water to benzene causes at first only a slow increase above the value of 2 (for pure benzene). A short discussion of the description of the dielectric constant of such polar-nonpolar mixtures for wide ranges of density is given. - The solubility of anthracene in high density water to 250 °C was measured spectroscopically. Data are given. The “enhancement factor” is high at low temperature but decreases to unity at 250 °C and a water density of 1 g . cm−3

Effect of solute–solvent interactions on DPPH radical scavenging efficiency of some flavonoid antioxidants in various binary water–methanol mixtures

2015 ◽  
Vol 93 (5) ◽  
pp. 558-563 ◽  
Author(s):  
Morteza Jabbari ◽  
Hamid Reza Moallem
Keyword(s):  
Pure Water ◽  
Radical Scavenging ◽  
Regression Equations ◽  
Aqueous Mixtures ◽  
Dpph Radical ◽  
Testing Methods ◽  
Solvent Interactions ◽  
Polarity Parameter ◽  
Scavenging Efficiency ◽  
Dpph Radical Scavenging

Scavenging ability of three kinds of natural flavonoid antioxidants including chrysin, naringenin, and quercetin against the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical was evaluated by the UV-vis spectrophotometric technique in different aqueous mixtures of methanol (50%–90% v/v) at physiological pH. The studied flavonoids showed their activity to be comparable with ascorbic acid (vitamin C), which is used as a standard reference material in most testing methods. Our findings indicated that an increase in the organic solvent percentage (v/v) has different effects on the radical scavenging efficiency of flavonoids presumably due to solute–solvent interactions. These variations were analyzed in light of various simple and multiple regression equations using the normalized polarity parameter ([Formula: see text]) and Kamlet, Abboud, and Taft solvatochromic parameters. Moreover, The IC50 values of the samples were then obtained by the Yasuda–Shedlovsky extrapolation procedure in pure water.

scholarly journals Surface tension of aqueous binary mixtures under the supercooled conditions – Development of the measuring technique and preliminary data for water + lower alcohols

2018 ◽  
Vol 180 ◽  
pp. 02118 ◽  
Author(s):  
Václav Vinš ◽  
Jiří Hykl ◽  
Zbyněk Nikl ◽  
Miroslav Čenský ◽  
Jan Hrubý
Keyword(s):  
Surface Tension ◽  
Binary Mixtures ◽  
Capillary Tube ◽  
Pure Water ◽  
Capillary Rise ◽  
Solute Concentration ◽  
Liquid Column ◽  
Measuring Technique ◽  
Aqueous Mixtures ◽  
Experimental Apparatus

An experimental apparatus originally developed for the measurement of surface tension of supercooled water was modified such that it allows for measurement of binary aqueous mixtures. The measuring principle based on the capillary rise technique is similar to that employed in the previous measurements with pure water [J. Hrubý et al., J. Phys. Chem. Lett. 5 (2014) 425 and V. Vinš et al., J. Phys. Chem. B 119 (2015) 5567]. The temperature dependence of the surface tension is determined from the measured height of the liquid column elevated in a vertical capillary tube with an inner diameter of 0.32 mm. The aqueous liquid rises to a height of 60 mm to 95 mm depending on the solute concentration and the temperature. Preliminary tests performed with the binary mixtures of water with methanol, ethanol, and n-propanol at various concentrations and temperatures down to –28 °C approved functionality of the measuring technique. Some difficulties, such as influence of impurities on the liquid column elevation or formation of bubbles in the liquid column, were observed. The experimental apparatus is further being modified in order to obtain more accurate data for various aqueous mixtures.

Viscosity of aqueous mixtures of silver and thallium nitrates with calcium or cadmium nitrates from pure fused salt to pure water

1990 ◽  
Vol 19 (7) ◽  
pp. 693-709 ◽  
Author(s):  
Maurice Abraham ◽  
Ioannis Ziogas ◽  
Marie-Christine Abraham
Keyword(s):  
Pure Water ◽  
Aqueous Mixtures ◽  
Fused Salt

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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