Thermochemical Purification, Technical Properties, and Characterization of Ethiopian Diatomite from Adami-Tulu Deposit

Abstract

This article presents the purification and characterization of several application-oriented properties of Ethiopian diatomite mineral collected from Adami-Tulu deposit. The diatomite samples were purified by thermochemical method conducted in 6 M H2SO4 at 360–368 K for 48 h. The chemical, mineralogical, textural, morphological and thermal properties of the raw diatomite and treated diatomite were then characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, dynamic light scattering particle size analyzer, Fourier transform infrared spectroscopy, thermogravimetry analyzer, Inductively coupled plasma optical emission spectrometry, N2 sorption techniques, and Mercury intrusion porosimetry. Based on the results, the diatomite was composed of mainly amorphous silica, and a small amount of quartz, feldspar, cristobalite and montmorillonite. The diatom frustules showed cylindrical and platy morphological shapes. The treatment for 24 h decreased the impurities, and increased the silica content and Brunauer–Emmett–Teller surface area to 95 wt% and 29 m2/g, respectively. Moreover, interconnected mesopores and a significant amount of macropores were found. From the obtained results, it can be concluded that the diatomite from Adami-Tulu region is moderate in quality, and the application of a hot acid leaching was a valid approach to produce high-quality diatomite, which can be used in several industrial applications.