Density, Viscosity, and Thermal Conductivity of Aqueous Ethylene, Diethylene, and Triethylene Glycol Mixtures between 290 K and 450 K

Sun, Tongfan; Teja, Amyn S.

doi:10.1021/je025610o

Cited by 185 publications

(102 citation statements)

References 17 publications

(31 reference statements)

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“…The precision of density measurements is estimated to be better than 10 (Figure 1). Density values at different temperatures for the aqueous solutions of ethylene glycols are in a good agreement with those published by Sun and Teja [11] and Müller and Rasmussen [12].…”

Section: Densitysupporting

confidence: 89%

Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Adam

Al-Dujaili

Awwad

2014

ISRN Physical Chemistry

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Densities of aqueous solutions of Ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) were measured at temperatures from 293.15 to 318.15 K and molalities ranging from 0.0488 to 0.5288 mol⋅kg −1 . Volumes of all investigated solutions at a definite temperature were linearly dependent on the solute molality; from this dependence the partial molar volumes at infinite dilution were determined for all solutes. It was found that the partial molar volumes at infinite dilution ( 2,0 ) were concentration independent and slightly increase with increasing temperature. The partial molar volumes at infinite dilution ( 2,0 ) or the limiting apparent molar volumes of ethylene glycols were fitted to a linear equation with the number of oxyethylene groups ( ) in the solute molecule. From this equation a constant contribution of the terminal (OH) and the (CH 2 CH 2 O) groups to the volumetric properties was obtained. The thermal expansion coefficient ( 1,2 ) for all investigated solutions was calculated at temperatures from 293.15 to 318.15 K. The thermal expansion coefficients for all solutes increase with increasing temperature and molality. Values of ( 1,2 ) were higher than the value of the thermal expansion coefficient of the pure water.

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Section: Densitysupporting

confidence: 89%

Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Adam

Al-Dujaili

Awwad

2014

ISRN Physical Chemistry

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“…Ethylene glycol (Ͼ99% purity; Sigma) was added to obtain the following final concentrations: 11, 22, 32, 43, and 53% wt/wt. Viscosities of ethylene glycol (44), glycerol (45), and glucose (46) were obtained from the literature.…”

Section: Methodsmentioning

confidence: 99%

Measuring internal friction of an ultrafast-folding protein

Cellmer

Henry²,

Hofrichter³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

153

193

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Nanosecond laser T-jump was used to measure the viscosity dependence of the folding kinetics of the villin subdomain under conditions where the viscogen has no effect on its equilibrium properties. The dependence of the unfolding/refolding relaxation time on solvent viscosity indicates a major contribution to the dynamics from internal friction. The internal friction increases with increasing temperature, suggesting a shift in the transition state along the reaction coordinate toward the native state with more compact structures, and therefore, a smaller diffusion coefficient due to increased landscape roughness. Fitting the data with an Ising-like model yields a relatively small position dependence for the diffusion coefficient. This finding is consistent with the excellent correlation found between experimental and calculated folding rates based on free energy barrier heights using the same diffusion coefficient for every protein.funneled energy landscape ͉ Ising-like model ͉ Kramers ͉ polypeptide ͉ viscosity D espite the complexity of the protein folding process, the kinetics and mechanisms of folding can be usefully and accurately described by diffusion over barriers on a lowdimensional free-energy surface (1-5). For ultrafast-folding proteins, the barriers are small and the rates may be affected by the variation of the diffusion coefficient along the reaction coordinate. In addition to solvent friction, the diffusion coefficient is determined by internal friction, which reflects the ''roughness'' of the energy landscape that arises from drag because of intrachain interactions and escape from local minima on the energy surface (1, 4, 6, 7). Both theoretical studies (1,8) and simulations (4, 9, 10) indicate that the internal friction depends on position along the reaction coordinate, but there have been no experiments that address this important issue in the physics of protein folding. In this work, we obtain a quantitative measure of the contribution of internal friction to the dynamics of folding from experiments on the viscosity dependence of the kinetics for the ultrafast-folding villin subdomain. Fitting the data with an Ising-like theoretical model, moreover, yields information on the position dependence of the diffusion coefficient. Unlike all previous studies of the viscosity dependence of protein-folding kinetics (11-17), we carried out experiments under conditions where there is no effect of the viscogen on the equilibrium thermal unfolding, as was done in a previous study of ␣-helix and ␤-hairpin formation (18).For barriers Ͼϳ 3RT separating folded and unfolded states, Kramers theory (19) predicts that the relaxation rate, 1/ , is given by:where is the relaxation time, f and u are the folding and unfolding times, ⌬G f ‡ is the free energy barrier to folding, ⌬G u ‡ is the free energy barrier to unfolding, R is the gas constant, T is the absolute temperature, ( u ) 2 is the curvature in the unfolded free energy well, ( f ) 2 is the curvature in the folded free energy well, ( ‡ ) 2 is the curvature a...

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“…(Kestin et al, 1978;Perry and Green, 2008;Vargaftik et al, 1983). As for the physical properties of water-MEG mixtures, the work by Sun and Teja (2003) has been taken into account for evaluating their densities and viscosities as a function of the mass fraction of monoethylene glycol, of the temperature and of the properties of the two components constituting the binary system. As for the surface tension of aqueous monoethylene glycol solutions at T=298.15 K, the correlation found in the product guide provided by MEGlobal™ (MEGlobalTM, 2015) for monoethylene glycol aqueous solutions has been used:…”

Section: Experimental Setup and Liquid Phasesmentioning

confidence: 99%

The dual effect of viscosity on bubble column hydrodynamics

Besagni

Inzoli

Guido

et al. 2017

Chemical Engineering Science

110

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A B S T R A C TSome authors, in the last decades, have observed the dual effect of viscosity on gas holdup and flow regime transition in small-diameter and small-scale bubble columns. This work concerns the experimental investigation of the dual effect of viscosity on gas holdup and flow regime transition as well as bubble size distributions in a large-diameter and large-scale bubble column. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, and can be operated with gas superficial velocities in the range of 0.004-0.20 m/s. Air was used as the dispersed phase, and various water-monoethylene glycol solutions were employed as the liquid phase. The water-monoethylene glycol solutions that were tested correspond to a viscosity between 0.9 mPa s and 7.97 mPa s, a density between 997.086 kg/m 3 and 1094.801 kg/m 3 , a surface tension between 0.0715 N/m and 0.0502 N/m, and log 10 (Mo) between −10.77 and −6.55 (where Mo is the Morton number). Gas holdup measurements were used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. An image analysis method was used to investigate the bubble size distributions and shapes for different gas superficial velocities, for different solutions of watermonoethylene glycol. In addition, based on the experimental data from the image analysis, a correlation between the bubble equivalent diameter and the bubble aspect ratio was proposed. The dual effect of viscosity, previously verified in smaller bubble columns, was confirmed not only with respect to the gas holdup and flow regime transition, but also for the bubble size distributions. Low viscosities stabilize the homogeneous flow regime and increase the gas holdup, and are characterized by a larger number of small bubbles. Conversely, higher viscosities destabilize the homogeneous flow regime and decrease the gas holdup, and the bubble size distribution moves toward large bubbles. The experimental results suggest that the stabilization/destabilization of the homogeneous regime is related to the changes in the bubble size distributions and a simple approach, based on the lift force, was proposed to explain this relationship. Finally, the experimental results were compared to the dual effect of organic compounds and inorganic compounds: future studies should propose a comprehensive theory to explain all the dual effects observed.

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Density, Viscosity, and Thermal Conductivity of Aqueous Ethylene, Diethylene, and Triethylene Glycol Mixtures between 290 K and 450 K

Cited by 185 publications

References 17 publications

Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Measuring internal friction of an ultrafast-folding protein

The dual effect of viscosity on bubble column hydrodynamics

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