For the characterization of diatomite from Vitachevo (Kavadarci, Republic of Macedonia), chemical, mineralogical and structural examinations were performed. The results of the chemical analysis of diatomite revealed a SiO2 content exceeding 89%. The X-ray powder diffraction indicates presence of amorphous phase, as well as presence of crystalline phases quartz, muscovite and cristobalite. The results of the infra-red confirm the results of the XRPD analyses. The SEM examinations explain the high porosity of the material and the presence of pores with nano-metric dimensions ranging from 300-600 nm. Based on the performed analysis the raw material can be utilized for various uses

Boev, Blazo

Boev, Ivan

Makreski, Petre

Pavlovski, Blagoj

Reka, Arianit

UGD Academic Repository

  CHEMICAL, MINERALOGICAL AND STRUCTURAL CHARACTERIZATION OF DIATOMITE FROM REPUBLIC OF MACEDONIA  Arianit A. Reka1*, Blagoj Pavlovski2, Blazо Boev3, Ivan Boev3, Petre Makreski4 1 – Faculty of Natural Sciences and Mathematics, University of Tetovo, Ilinden n.n., 1200 Tetovo, Republic of Macedonia,  2 – Faculty of Technology and Metallurgy, Ss. Cyril and Methodius University, Ruger Boskovic bb, 1000 Skopje, Republic of Macedonia 3 – Faculty of Natural and Technical Sciences, Goce Delčev University, Blvd. Krste Misirkov 10-A, 2000 Štip, Republic of Macedonia 4 – Faculty Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Arhimedova 5, 1000 Skopje, Republic of Macedonia (*e-mail: blazо.boev@ugd.edu.mk)    Abstract: For the characterization of diatomite from Vitachevo (Kavadarci, Republic of Macedonia), chemical, mineralogical and structural examinations were performed. The results of the chemical analysis of diatomite revealed a SiO2 content exceeding 89%. The X-ray powder diffraction indicates presence of amorphous phase, as well as presence of crystalline phases quartz, muscovite and cristobalite. The results of the infra-red confirm the results of the XRPD analyses. The SEM examinations explain the high porosity of the material and the presence of pores with nano-metric dimensions ranging from 300-600 nm. Based on the performed analysis the raw material can be utilized for various uses.  Кеy words: diatomite, mineralogical characterization, structural examinations   INTRODUCTION  Inorganic non-metallic materials are suitable for various uses. Silicon dioxide, also known as silica, is widely spread in nature and it occurs in various forms (Callister & Rethwisch, 2010; Holleman & Wiberg, 2007; Kingery, 1960; Iler, 1978) Republic of Macedonia is rich in amorphous silica based crude materials, and these materials have a wide spectrum of potential use and application (Cekova et al., 2013; Cekova et al., 2014; Pavlovski et al., 2011; Reka et al., 2014). Diatomaceous earth, as well as other inorganic materials that contain amorphous SiO2 such as trepel, are convenient and promising materials for the production of porous ceramics, refractory ceramics, special oxide ceramics, as well as widespread use as means for filtering, adsorbent, catalysts and other uses due to its natural porosity, low density and mineralogical composition (Reka et al., 2016; Reka et al., 2017). The raw material subject of this research is taken from Vitachevo (Kavadarci, Republic of Macedonia).  METHODS The chemical composition of diatomite is determined with the classical silicate analysis. The characterization from the mineralogical point of view was performed by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). XRPD analysis was performed on Rigaku Ultima IV X-ray diffractometer equipped with D/teX high-speed 1-dimensional detector using CuKα radiation (λ = 1.54056 Å) in 2θ range from 10 to 60°. The accelerating voltage and the current power were set to 40 kV and 40 mA, respectively. The Perkin-Elmer FTIR system 2000 interferometer was employed to record the IR spectra in 4000–500 cm–1 range using the KBr pellet method. The spectral resolution was set to 4 cm–1 and the spectrum merged from 16 measurements. Scanning electron microscopy (SEM) of the products was performed with energy dispersive X-ray spectroscopy (EDX) employing FEI Quanta 3D FEG dual beam microscope.   RESULTS   The physical-mechanical analysis of diatomite showed that it represents a white to grey rock. The subject diatomite has a massive homogeneous texture and shell-like fragility. It represents a light, soft, weakly bound rock, and in dry condition exhibit compressive strength of 3.4–4.6 MPa. The rock's bulk mass and porosity are ranging from 0.55 to 0.60 g/cm3 and 73–75%, respectively. Results of the XRPD analysis of the diatomite (Fig. 1) depicts amorphous behaviour of the sample manifested by the appearance of one complex “bump” widely positioned between 15 and 30° (2θ) with the maximum peaking in the 18–26.7° range. However there is presence of the following crystalline phases: quartz, muscovite and cristobalite. The IR spectrum of diatomite exhibits absorption bands at 800 cm-1 as result of the bending vibrations of Si-O-Si framework, whereas the band at 1103 cm-1 is as result of the stretching vibrations of Si-O-Al units. The band at 1636 cm-1 is due to bending vibrations from the absorbed water, while the band at 3435 cm-1 is due to the stretching vibration of the absorbed water molecules.  The results from the scanning electron microscopy show presence of various skeletal shapes and their morphological characteristics, skeletons of microorganisms which have clearly visible pores and canals. Majority of the pores are open (and do not contain impurities) and are in the range 300-600 nm.   DISCUSSION Based on the detailed examination of the diatomite from Vitachevo (Kavadarci, Republic of Macedonia), the crude diatomite represents a weakly bound, soft loose rock with a white to greyish white color; it has a low bulk mass and high porosity. The results obtained from the chemical composition of diatomite, indicate material with high purity, with a dominant presence of SiO2 (89.15%), while the presence of the remaining oxides are as follows: Al2O3 (0.64 wt. %), Fe2O3 (0.23 wt. %), TiO2 (0. 031 wt. %), CaO (0.20 wt. %), MgO (0.07 wt. %), MnO (0.005 wt. %), P2O5 (0.03 wt. %), K2O (0.11 wt. %), Na2O (0.10 wt. %) and LOI 9.10. The XRD analyses show that the material depicts amorphous behavior as well as presence of crystalline phases (quartz, muscovite and cristobalite). The infra-red spectra of the raw materials shows the characteristic absorption bands at 800 cm-1 as result of the bending vibrations of Si-O-Si framework, whereas the band at 1103 cm-1 is as result of the stretching vibrations of Si-O-Al units. The band at 1636 cm-1 is due to bending vibrations from the absorbed water, while the band at 3435 cm-1 is due to the stretching vibration of the absorbed water molecules. The scanning electron microscopy results shows presence of various skeletal shapes and their morphological characteristics, skeletons of microorganisms which have clearly visible pores and canals. Majority of the pores are open (and they do not contain impurities) and are in the range 300-600 nm.    Figure 1. XRPD pattern of diatomite from Vitachevo (Kavadarci)      CONCLUSIONS Based on the abovementioned results the following can be concluded: the raw material represents a white to grayish rock, porous, soft and weakly bound. A high quality diatomaceous earth, with high percent of SiO2 (89%), and small amount of impurities: Al2O3 (0.64 wt. %), Fe2O3 (0.23 wt. %), TiO2 (0. 031 wt. %), CaO (0.20 wt. %), MgO (0.07 wt. %), MnO (0.005 wt. %), P2O5 (0.03 wt. %), K2O (0.11 wt. %), Na2O (0.10 wt. %), while LOI is 9.10%.  From the mineralogical point of view, the diatomaceous earth represents amorphous material with presence of crystalline phases (quartz, muscovite and cristobalite). The results from the scanning electron microscopy shows presence of various skeletal shapes and their morphological characteristics, skeletons of microorganisms which have clearly visible pores and canals. Majority of the pores are open (and they do not contain impurities) and are in the range 300-600 nm.   REFERENCES  Callister, W. D., Rethwisch, D. G., 2010. Material Science and Engineering, John Wiley & Sons Inc. 464–465 pp.  Cekova, B., Pavlovski, B., Spasev, D., Reka, A. A., 2013. Structural examinations of natural raw materials pumice and trepel from Republic of Macedonia, Proceedings of the XV Balkan Mineral Processing Congress, Sozopol, Bulgaria, 73-75.  Cekova, B., Pavlovski, B., Markoska, V., Reka, A. A., 2014. The adsorption character of zeolites, type 4a, obtained by natural raw trepel Bitola, R. Macedonia, Int. J. Eng. Sci. Innov. Technol, 3, 449–454.  Holleman, A. F., Wiberg, E., 2007. Lehrbuch der Anorganischen Chemie, Walter de Gruyter, Berlin, New York. 975 pp.  Iler, R. K., 1978.  The Chemistry of Silica. A Wiley-Interscience Publication, John Wiley & Sons. 15–16 pp.  Kingery, W. D., 1960. Introduction to Ceramics, John Willey & Sons, Inc.   Pavlovski, B., Jančev, S., Petreski, Lj., Reka, A., Bogoevski, S., Boškovski, B., 2011. Trepel – a peculiar sedimentary ock of biogenetic origin from the Suvodol village, Bitola, R. Macedonia, Geologica Marcedonica, 25 (1), 67–72.  Reka, A. A., Anovski, T., Bogoevski, S., Pavlovski, B., Boškovski, B., 2014. Physical-chemical and mineralogical-petrographic examinations of diatomite from deposit near village of Rožden, Republic of Macedonia, Geologica Macedonica, Vol. 28, No. 2, 121–126.  Reka, A.A.,, Durmishi, B.H.,, Jashari, A.,, Pavlovski, B., Buxhaku, N., Durmishi, A., 2016. Physical-chemical and mineralogical-petrographic examinations of trepel from Republic of Macedonia, Int. J. Innov. Stud. Sci. Eng. Technol. 213–17.  Reka, A. A., Pavlovski, B., Makreski, P., 2017. New optimized method for low-temperature hydrothermal production of porous ceramics using diatomaceous earth, Ceram. Int. 43, 12572–12578.  

Chemical, mineralogical and structural characterization of diatomite from Republic of Macedonia

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Chemical, mineralogical and structural characterization of diatomite from Republic of Macedonia

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