Fourier-Transform Infrared Study of Ethylene Glycol Monoethyl Ether Adsorbed on Montmorillonite: Implications for Surface Area Measurements of Clays

Abstract

Abstract-Infrared spectra of 2-ethoxyethanol (ethylene glycol monoethyl ether, EGME) adsorbed on Camontmorillonite were obtained using diffuse-reflectance infrared-Fourier-transform (DRIFT) and attenuated total-reflectance (ATR) spectroscopy. The molecular conformation of adsorbed EGME shows predominantly a gauche configuration for the CH2-CH2 linkage as originally present in the liquid. The orientation of the adsorbed EGME molecule in the interlamellar region of the clay was deduced from measurements of the polarized ATR spectra. The planar zig-zag skeleton of the molecule appears to have its long axis tilted at an angle of 44 ~ to the clay surface; the molecule is in van der Waals contact with both adjacent surfaces. Further, the plane of the skeleton of the molecule is tilted at an angle of 69 ~ to the clay surface. This orientation leads to estimates of the d-value of the clay-EGME complex and of the surface area occupied by each molecule. These values are in excellent agreement with independent measurements of both parameters. The full surface coverage on montmorillonite is represented by a single layer of tilted EGME molecules shared by two adjacent clay sheets; each molecule occupies a total surface area consisting of one portion (25.4 A2) on the lower surface of the interlayer plus another portion (14.8 ,~z) on the upper surface. The implication of this model for materials such as kaolinite, where adsorption takes place on the external surface only, is that on these materials each EGME molecule occupies 20/~2 at full surface coverage.

Injectable silk-polyethylene glycol hydrogels

“…3A). The strong peak shown at wave numbers lower than 1200 cm À1 and the peak centered on 2900 cm À1 are a result of residual PEG, as reported in the literature [26]. PEG did not show peaks in the amide I and II band region, and thus had a negligible influence on silk structural analysis.…”

Conformational Studies with Density Functional Theory of Ethylene Glycol as Intermediate

“…The corresponding FTIR [12] wave numbers and intensities with Raman active intensities corresponding to assigned functional groups with stretching and bending modes were tabulated in Table-2. These computed results signify that the infrared and Raman spectra are in good agreement with the experimental and theoretical values reported [9][10][11]. In this study, we have performed a frequency calculation to obtain the spectroscopic signature of ethylene glycol monomer.…”

Effects of Iron Oxidation State on the Specific Surface Area of Nontronite

“…To determine the effect of freezedrying on the ability of the clay to rewet, several freezedried samples were resuspended in deionized water and their equilibrium water contents determined at 3-atm (3) was somewhat more difficult, but was also considered fulfilled in this study based on the following observations. Any of the following phenomena should change the amount of EGME adsorbed: (1) a rearrangement of clay layers resulting in the complete collapse of some layers and a corresponding decrease in available surface area; (2) a sufficient partial collapse of some clay layers to prevent two full layers of EGME from entering the interlaminar spaces, such as reported by Nguyen et aL (1987) for Ca-montmoriUonite; and (3) a change in the interaction energy between the surface and the adsorbate molecule, which could result in only a single layer or less of EGME within the interlayer region. Occurrence of either phenomenon (2) or (3) should prevent fulfillment of condition (3) above, and EGME adsorption should underestimate S,,.…”