Structural characterization of four south african fly ashes and their structural changes with β-cyclodextrin

This article examines the structural characteristics of four South African fly ashes and their structural changes with β-cyclodextrin so as to compare their structural responses to fly ash-β-cyclodextrin (FA-βCD) composite. The four different fly ashes, obtained from different power stations in South Africa were subjected to x-ray fluorescence (XRF), particle size distribution, x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. FA-βCD composites were subjected to XRD and FTIR analyses. The XRF analysis showed that all the fly ash samples used are in class F with SiO₂ + Al₂O₃ + Fe ₂O₃ greater than 70%. The average particle sizes of all fly ash samples were less than 0.075 mm; the major mineral phase in all fly ash samples was quartz (SiO₂). The FTIR analysis showed Si-O-Si asymmetric and Al-O symmetric stretching vibrations in all fly ash samples. FA-βCD composites for all the fly ashes revealed additional upcoming peaks between diffraction angles (2θ) 10° and 25°, which was not in the raw fly ashes. Shift in FTIR spectra frequencies and an additional peak at approximately 1155 cm^-1 attributed to O-Si-O bending vibration were observed in all the composite samples.