Infrared Attenuated Total Reflectance Spectroscopy: An Innovative Strategy for Analyzing Mineral Components in Energy Relevant Systems

Abstract

The direct qualitative and quantitative determination of mineral components in shale rocks is a problem that has not been satisfactorily resolved to date. Infrared spectroscopy (IR) is a non-destructive method frequently used in mineral identification, yet challenging due to the similarity of spectral features resulting from quartz, clay, and feldspar minerals. This study reports on a significant improvement of this methodology by combining infrared attenuated total reflection spectroscopy (IR-ATR) with partial least squares (PLS) regression techniques for classifying and quantifying various mineral components present in a number of different shale rocks. The developed multivariate classification model was calibrated using pure component mixtures of the most common shale minerals (i.e., kaolinite, illite, montmorillonite, calcite, and quartz). Using this model, the IR spectra of 11 real-world shale samples were analyzed and evaluated. Finally, the performance of the developed IR-ATR method was compared with results obtained via X-ray diffraction (XRD) analysis.

Microwave-Assisted Dip Coating of Aloe Vera on Metallocene Polyethylene Incorporated with Nano-Rods of Hydroxyapaptite for Bone Tissue Engineering

“…These shifts were supposed to appear owing to the presence of the minerals available in Aloe vera gel. This result is in accordance with the peaks formed between 400-500 cm −1 and 500-600 cm −1 , demonstrating Si-O bending and C-H stretch as in some previous studies [41]. Figure 4 represents the 100× and 500× 3D Hirox digital microscopy images of mPE-nHA and Aloe vera dip-coated mPE-nHA.…”

Development of far-infrared attenuated total reflectance spectroscopy for the mineralogical analysis of shales

“…The model was validated against the same 28 shales and the RMSEC, RMSECV, RMSEP and R 2 for each mineral are shown in Table 4. The RMSEC and RMSECV values are significantly lower than the first model and comparable with other studies in literature [10,18]. The R 2 calibration values vary more widely than the first model.…”

“…These bands are all lattice modes similar to the ones found in calcite [20,28,39]. The mid-infrared spectra of the carbonate minerals tend to look similar considering that they involve mainly internal vibrations of the CO 3 2À ion [10]. However, the farinfrared spectra seem to be more discernible since they entail lattice vibrations and any substitution of one cation for another will result in significant peak shifts [28].…”

“…In albite, the bands between 250 cm À1 and 100 cm À1 are believed to be due to the motion of the sodium ion [41]. The differentiation of feldspars such as albite and other network silicates like quartz using MIR spectra is possible, but should be considerably enhanced using the FIR [10]. This is because substitution of one cation for another along with changes in the silica network causes considerable differences in the lattice modes [42].…”

“…Similarly, infrared spectroscopy (IR) is another method that has been used for a number of years to provide chemical information and assess the structural properties of a wide range of inorganic and organic materials [7]. In particular, a wealth of qualitative and quantitative data pertaining to the mineralogical composition [8][9][10][11], hydrocarbon potential/yield [12,13], kerogen type/maturation [12], and total organic carbon content/geochemistry [14,15] has been obtained in the mid-infrared (MIR) region between 4000 and 400 cm À1 . The MIR spectrum comprises a number of fundamental modes of vibration (i.e., stretching and bending movements) that involve either a change in the bond length or bond angle [7].…”