Baseline Studies of the Clay Minerals Society Source Clays: Infrared Methods

Abstract

Infrared (IR) spectroscopy has a long and successful history as an analytical technique and is used extensively (McKelvy et al., 1996; Stuart, 1996). It is mainly a complementary method to X-ray diffraction (XRD) and other methods used to investigate clays and clay minerals. It is an economical, rapid and common technique because a spectrum can be obtained in a few minutes and the instruments are sufficiently inexpensive as to be available in many laboratories. An IR spectrum can serve as a fingerprint for mineral identification, but it can also give unique information about the mineral structure, including the family of minerals to which the specimen belongs and the degree of regularity within the structure, the nature of isomorphic substituents, the distinction of molecular water from constitutional hydroxyl, and the presence of both crystalline and non-crystalline impurities (Farmel, 1979).

Possible mechanism of structural incorporation of Al into diatomite during the deposition process I. Via a condensation reaction of hydroxyl groups

“…The bands at 3420 and 1630 cm À1 are attributed to the O-H stretching and deformation of adsorbed water on the Dt surface [38], respectively. Moreover, the bands at 3625 and 910 cm À1 in the Dt spectrum are assigned to the O-H stretching and deformation vibrations of the clay minerals attached to the surface of diatomite, respectively, and the 536 cm À1 band is attributed to the Si-O-Al vibration of the clay mineral impurity [40]. The clay mineral bands are weak, indicating that only a few clay minerals are attached to the surface of diatomite.…”

Development and characterization of co-loaded curcumin/triazole-halloysite systems and evaluation of their potential anticancer activity

“…The frequency and assignments of each vibrational mode are based on previous halloysite reports (Yuan et al, 2008;Tonle et al, 2003;Vansant et al, 1995;White and Tripp, 2000;Madejova and Komadel, 2001;Vranken et al, 1992). Compared to p-HNT, 1 exhibits the CH 2 asymmetric and symmetric stretching at 2930 cm À1 and 2850 cm À1 respectively, the CH 2 scissoring at 1470 cm À1 and the stretching of the azido groups at 2103 cm À1 .…”

Fourier Transform Infrared Spectroscopy of Clay Size Fraction of Cretaceous-Tertiary Kaolins in the Douala Sub-Basin, Cameroon

“…In this study, the method used for ATR spectroscopy is that described by [12]: Each < 2 µm sample was placed in contact with an ATR crystal (ZnSe). The ZnSe crystal is preferably used because it produces the widest transmission range for complete spectra.…”

“…The IR spectra were recorded using a Brucker Alpha Platinum ATR FTIR spectrometer (made in USA), in the MIR regions (4000-400 cm −1 ) and with a resolution of 4 cm −1 . The peaks obtained were compared to those of the Georgia kaolins (KGa1b and KGa-2), known for their high grade (high purity and crystallinity), which were also analysed using ATR [12]. The samples were described as ordered, partially ordered and poorly ordered, based on the empirical classification of [28]: (i) Ordered (OH stretching and bending bands are clearly resolved; ii) Partially ordered (individual OH bands at 3670 cm −1 , 3650 cm −1 and 938 cm −1 have low intensities but can be identified); iii) Poorly ordered (only one band near 3660 cm −1 or inflexions near 3670 cm −1 , 3650 cm −1 and 938 cm −1 are observed in the spectra).…”

“…It is used to characterise functional groups in clay minerals and to fingerprint specific minerals [12,13]. Unlike X-ray powder diffraction, it has proven to be a rapid and cost-effective technique in determining the degree of structural disorder of clay minerals [12].…”