*2.1.2 Methods*

We analyzed the morphology of the raw fly ash samples using scanning electron microscopy (SEM;LEO SEM 1450), the molecular structure using Fourier-transform infrared spectroscopy (FTIR;Perkin Elmer 100 spectrum), the mineralogy using X-ray diffraction (XRD; X-ray generator, Philips PANalytical


#### **Table 1.**

*Chemical composition of the sand dune (western Algeria).*


#### **Table 2.**

*Chemical composition of the fresh fly ash of eggshell (FAES).*

pw3830), and the chemical composition using XRF (dispersion spectrometer, Philips 1404 wavelength).
