[01] Azimi Pirsaraei Seyed Reza, Occupational Health Engineering Department, Faculty of Medical Sciences, Tarbiat Modares University, Jalal Ale Ahmad Highway, Tehran, IR Iran. [02] Asilian Mahabadi Hasan, Occupational Health Engineering Department, Faculty of Medical Sciences, Tarbiat Modares University, Jalal Ale Ahmad Highway, Tehran, IR Iran. [03] Jonidi Jafari Ahmad, Environmental Engineering Department, Faculty of Health, Iran University of Medical Sciences, Shahid Hemmat Highway, Tehran, IR Iran. [04] Farahmandkia Zohreh, Analytical Chemistry & Chemistry Laboratory, Faculty of Health, Zanjan University of Medical Sciences, Parvin Etesaami, Zanjan, IR Iran. [05] Taran Jafar, Analytical Chemistry & Chemistry Laboratory, Faculty of Health, Zanjan University of Medical Sciences, Parvin Etesaami, Zanjan, IR Iran.

The characterizations of a natural diatomite such as chemical compositions, specific surface area, total pore volume, pore size distribution and XRD were studied. The diatomite that was treated only with sulfuric acid displayed a larger surface area, expanded total pore volume and increased pore size in comparison with both washed natural diatomite with deionized water (D-H2O) and the diatomite treated with sulfuric acid then calcinated at 550°C (D-H2SO4+550). The specific surface area and total pore volume were increased 46.63% and 71.40%, respectively. The results showed that the diatomite was composed of cristobalite, quartz and feldspar phases. Acid treatment and then calcination at 550°C changed the Si/Al ratio and grew the crystallite size. BJH with DFT analysis showed that the diatomite had very disordered micro/mesoporous pore networks. The pore size distribution of the diatomite was from 1.4100 nm. Its isotherm was type IV and showed a long hysteresis loop that resembled the H3 type on the basis of the IUPAC classification. Therefore, the diatomite that was treated only with sulfuric acid can be to serve as a catalyst support or an adsorbent.

Natural Diatomite, Acid Treatment, X-Ray Diffraction, Crystallite Size Determination, Scanning Electron Microscopy

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