Phase transitions of silica in diatomite from Besiste (North Macedonia) during thermal treatment

Arianit, Reka and Pavlovski, Blagoj and Boev, Blazo and Boev, Ivan and Makreski, Petre (2019) Phase transitions of silica in diatomite from Besiste (North Macedonia) during thermal treatment. Zbornik radova knjiga sažetaka: II Kongres geologa Bosne i Hercegovine sa međunarodnim učešćem, 6. ISSN 1840-4073

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Introduction Diatomaceous earth (DE) is one of the raw materials that is very intensively examined. This is mainly to its application in ceramic, pharmaceutical, chemical, food industries, in the drinking and waste water treatments, as well as in the development of new technologies i.e fabrication of semiconductors, optical fibers, solar cells etc. The diatomaceous earth presented in this work is collected from Besiste region. For the characterization of the DE physical-mechanical, chemical, XRPD, SEM and IR analysis were performed. From the physical-mechanical characterization, the materials represents a white to grayish rock with homogenous texture and shell-like fragility. The diatomaceous earth is very light, soft, and weakly bound, while in dry state exhibits compressive strength from 2.20–3.20 MPa. The total porosity ranges 68–72%, whereas the density is 2.01–2.06 g/cm3. Results obtained from ICP-MS show the following chemical composition: SiO2 (86.338%), Al2O3 (3%), Fe2O3 (2.8 %), CaO (0.76%), TiO2 (0.139%), K2O (0.687%), Na2O (0.191%), MnO (0.0006%), MgO (0.28%), and P2O5 (0.139%). The results from the X-ray powder diffraction of the raw diatomaceous earth indicate amorphous SiO2 phase with the established presence of muscovite and quartz. The XRPD of the thermally treated diatomaceous earth at 950 C for a period of 1 hour, shows increase of the quartz peak while the peak for muscovite is significantly reduced. Evident is presence is the formation of tridymite in the sample. The results of the SEM analysis of the DE provide valuable information for the morphology, surface characteristics as well as the nanometric pores present in the raw material.

Item Type: Article
Uncontrolled Keywords: diatomite, scanning electron microscopy, XRDP, phase transition
Subjects: Natural sciences > Earth and related environmental sciences
Divisions: Faculty of Natural and Technical Sciences
Depositing User: Biljana Kosturanova
Date Deposited: 15 Nov 2019 12:12
Last Modified: 15 Nov 2019 12:12

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