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Open AccessArticle

Flow and Tableting Behaviors of Some Egyptian Kaolin Powders as Potential Pharmaceutical Excipients

1
Geology Department, Faculty of Science, Al Azhar University in Cairo, Nasr City 11884, Egypt
2
Andalusian Institute of Earth Sciences IACT, Spanish National Research Council CSIC—University of Granada UGR, 18100 Armilla, Granada, Spain
3
Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Belgrade, 11221 Belgrade, Serbia
4
Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Granada, 18071 Granada, Spain
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(1), 23; https://doi.org/10.3390/min10010023
Received: 19 November 2019 / Revised: 17 December 2019 / Accepted: 21 December 2019 / Published: 26 December 2019
(This article belongs to the Special Issue Special Clays and Their Applications)
The present work aimed at assessing the pharmaceutical tableting properties of some Egyptian kaolin samples belong to the Abu Zenima kaolin deposits (estimated at 120 million tons). Four representative samples were selected based on kaolinite richness and their structural order-disorder degree, and after purification, they were dried at 70 °C and heated from room temperature up to 400 °C (10 °C/min). Mineralogy, micromorphology, microtexture, granulometry, porosimetry, moisture content, bulk and tapped density, direct and indirect flowability, and tableting characteristics are studied. Results indicated that purified kaolin samples were made up of 95–99% kaolinite, <3% illite, 1% quartz and 1% anatase. The powder showed mesoporous character (pore diameters from 2 to 38 nm and total pore volume from 0.064 to 0.136 cm3/g) with dominance of fine nanosized particles (<1 μm–10 nm). The powder flow characteristics of both the ordered (Hinckley Index HI > 0.7, crystallite size D001 > 30 nm) and disordered (HI < 0.7, D001 < 30 nm) kaolinite-rich samples have been improved (Hausner ratio between 1.24 and 1.09) as their densities were influenced by thermal treatment (with some observed changes in the kaolinite XRD reflection profiles) and by moisture content (variable between 2.98% and 5.82%). The obtained tablets exhibited hardness between 33 and 44 N only from the dehydrated powders at 400 °C, with elastic recovery (ER) between 21.74% and 25.61%, ejection stress (ES) between 7.85 and 11.45 MPa and tensile fracture stress (TFS) between 1.85 and 2.32 MPa, which are strongly correlated with crystallinity (HI) and flowability (HR) parameters. These findings on quality indicators showed the promising pharmaceutical tabletability of the studied Egyptian kaolin powders and the optimization factors for their manufacturability and compactability. View Full-Text
Keywords: Egyptian kaolin; powder; microstructure; micrometrics; flowability; tableting properties; manufacturability; table hardness Egyptian kaolin; powder; microstructure; micrometrics; flowability; tableting properties; manufacturability; table hardness
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Awad, M.E.; López-Galindo, A.; Medarević, D.; Đuriš, J.; El-Rahmany, M.M.; Ibrić, S.; Viseras, C. Flow and Tableting Behaviors of Some Egyptian Kaolin Powders as Potential Pharmaceutical Excipients. Minerals 2020, 10, 23.

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