Dielectric Relaxation Time and Relaxation Time Distribution of Alcohol−Water Mixtures

Abstract

Complex permittivity was measured in the frequency range from 10 MHz to 20 GHz at 25°C for water mixtures of 22 aliphatic alcohols. The molecular structures of these alcohols systematically changed with the number of carbon atoms and hydroxyl groups, and their positions in the molecules. The asymmetric shape of the frequency dependence of the dielectric loss for the primary relaxation process was observed for each mixture. The broadness of the asymmetric dielectric loss depends on the water content, and the broadest dielectric loss was observed in the water mole fraction range of 0.65 < x w < 0.85. There is a strong correlation between the broadness of dielectric loss and the number of carbon atoms in the alcohol molecule. Deviations of observed relaxation times from those estimated for ideal mixtures depend on the number of carbon atoms except for the mixtures of water and alcohols with large alkyl groups, which form a micelle-like structure. These experimental results are interpreted on the basis of a model of three kinds of cooperative domains coexisting in the mixtures.

Solvent effects in the catalytic hydrotreament of haloaromatics over Pd/Al2O3 in water+organic mixtures

“…The e E and v E parameters represent the excess properties, which serve to correct for deviations associated with the methanol+ water mixture relative to ideal behaviour and numerical values are available in the literature (Herrá ez and Belda, 2006;Smith et al, 1998). Indeed, when mixing water with alcohols, a reorganization of the overall solution structure occurs with the formation of clusters wherein water accommodates the hydrophilic/hydrophobic organic components via H-bonding/physical interactions (Jouyban et al, 2004;Sengwa and Abhilasha, 2006;Sudo et al, 2002). The continuous formation/destruction of these clusters results in an excess of the thermodynamic properties (including e and v) in the mixture, i.e.…”

Dynamics and Glass Transition of Aqueous Solutions of Molecular Liquid, Polymer, and Protein Studied by Broadband Dielectric Spectroscopy

“…In solutions containing solutes with a low molecular weight, such as alcohols (molecular weight, M W 100), the observed relaxation curve was asymmetric with respect to the loss peak above the separation temperature T S [39,40,55,[59][60][61], as shown in Fig. 9.3a.…”

Dielectric Relaxation in Ethylene Glycol - Dimethyl Sulfoxide Mixtures as a Function of Composition and Temperature

“…The structure and dynamics of the hydrogen bonded ethylene glycol (HOCH 2 CH 2 OH) molecules are 417 very interesting and have been studied by various workers using different measurement techniques. 21,22 The four sites available for H-bonding in EG molecules promote a set of transient crosslinks between neighboring molecules. In such a case, relevant transient structures such as branched associated species and/or chains are formed.…”