Relative Permittivity Measurements of Gaseous, Liquid, and Supercritical Dimethyl Ether

Abstract

The relative permittivity ( r ) of dimethyl ether (DME) was measured as a function of temperature and pressure in the gaseous, liquid, and supercritical states. The temperature and pressure ranges studied were (303 to 403) K and (0.04 to 33.2) MPa, respectively. The relative permittivity was fitted to the reduced density (F r ) using the function ( r -1)/(2 r + 1), and the apparent dipole moment (µ * ) of the liquid phase was calculated using Kirkwood's theory of molecular polarizability.

Extraction of carotenoids and lipids from algae by supercritical CO2 and subcritical dimethyl ether

“…DME is the simplest form of ether, possessing the following characteristics: (i) DME has a low normal boiling point (−24.8 °C); therefore, it is not present in the final products at normal temperatures [17]; (ii) Relative permittivity of DME is 1.08 and 5.34 at 30.5 °C, in gaseous and liquid states, respectively. Liquefied DME has high affinity for oily substances [18] and partial miscibility with water [19]; (iii) DME has been approved as a safe extraction solvent for the production of foodstuffs and food ingredients by the European Food Safety Authority (EFSA) [20], by the Food Standards Australia New Zealand, and by the United States [21]. The EFSA panels also consider the intended use of dimethyl ether as an extraction solvent to remove fat from animal protein raw materials provided: (a) the defatted animal protein is submitted to vacuum, which assures that most of the volatile dimethyl ether is eliminated from the final animal protein products; (b) the maximum residual limit of dimethyl ether is 9 μgkg -1 of extracted animal proteins and; (c) the extracted proteins are used at a level of up to 2% in the final foodproduct, at which the Panel considers that there is no safety concern;…”

Thermodynamics of solvent-driven water extraction from hypersaline brines using dimethyl ether

“…For sodium and chloride ions, r i and q i values are taken from Mohs et al [51]. The solubility of NaCl in the organic phase of a water-DME-electrolyte mixture at liquidliquid equilibrium (LLE) is negligible as a result of the very low polarity of DME, which has a dielectric constant of 5.34 at 304 K and 6.3 MPa [37]. The concentration of NaCl in water extracted using SDWE with DME (c Extracted NaCl ) was experimentally measured for feed NaCl concentration (c Feed NaCl ) values of approximately 70 g kg −1 (moderate salinity, 1.19 mol kg −1 ) and 200 g kg −1 (high salinity, 3.42 mol kg −1 ).…”

“…Dimethyl ether (DME, CH 3 OCH 3 ) is a polar aprotic organic solvent that is partially miscible with water. The low polarity of DME, which has a dielectric constant of less than 5.0, minimizes the solubility of electrolytes in the organic phase at LLE enabling near perfect salt rejection [37]. DME's high volatility-a vapor pressure of 5.9 bar at 298 K-enables the rapid and efficient separation of water-DME mixtures after extraction using energy sources ranging from electrical power to ultra-low-grade, or "waste", heat (< 50 °C) [38].…”

Ethanol‐free extraction of resveratrol and its glycoside from Japanese knotweed rhizome by liquefied dimethyl ether without pretreatments

“…When the pressure is reduced to atmospheric pressure after extraction, DME is not present in the final products at room temperature. (b) Relative permittivity of liquefied DME is 5.34, 16 which indicates that it has a weak polarity. Therefore, liquefied DME has high affinity to oily substances and partial miscibility with water.…”