7 research outputs found
Flow and Tableting Behaviors of Some Egyptian Kaolin Powders as Potential Pharmaceutical Excipients
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 ÂșC and heated from room
temperature up to 400 ÂșC (10 ÂșC/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 95â99%
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 umâ10 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 ÂșC, 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.This work has been funded by the Egyptian Cultural Affairs and Missions Sector (Plan 2013â2014),
Ministry of Higher Education, in collaboration with the Group CTS-946 (Junta de AndalucĂa) and MINECO project
CGL2016-80833-R (Spain), and the grant funded by Erasmus+ KA1 mobility program 2016/2017
Enhanced antimicrobial activity and physicochemical stability of rapid pyro-fabricated silver-kaolinite nanocomposite
The present research aims to enhance the antimicrobial activity of kaolinite surfaces by a one-step cost-effective and energy-efficient dry thermal reaction, producing an antibacterial and antifungal silver-kaolinite (Ag-Kao) nanocomposite agent. Pharmaceutical grade kaolin powder samples, with variable kaolinite structural orderâdisorder degree, were homogeneously mixed with silver nitrate in a proportion 1:4 AgNO3:kaolin (w/w) and sintered at 400 °C for 30 min. The composition, microstructure, microtexture and surface characteristics of the pyro-fabricated nanocomposites were characterized by XRD/XRF diffractometry, differential scanning calorimetry DSC, FT-IR spectroscopy, TEM/EDX, zeta potential (mV) measured within the 2â12 pH range, and BET method. Physicochemical stability was evaluated by silver dissociation testing under close-neutral and acidic conditions with Ag content assay using ICP-OES. The resulting Ag-Kao nanocomposites exhibited bulk silver contents ranging from 9.29% to 13.32% with high physicochemical stability in both neutral and acidic mediums (Ag dissociation rate 1) produced platelet edge-clustered silver nanocrystals due to the abundance of the dangling hydroxyls on platelet edges, while the highly disordered kaolinite (HI < 1) provided homogeneous platelet basal-doped silver nanocrystals due to the presence of some residual charges by exposed basal hydroxyl groups with interplatelet silver diffusivity. At pH 2, the magnitude of the positive surface charge was influenced by the silver nanocrystal size. Nanocomposites with the smallest silver nanocrystals (10â5 nm) exhibited the highest positive zeta potential (+15.2 mV to +17.0 mV), while those with larger silver nanocrystals (up to 30 nm) indicated lower positive zeta potential values (+9.5 mV to +3.6 mV). Under the same testing conditions using the Mueller-Hinton broth microdilution method, the raw kaolin samples did not show any significant antimicrobial activity, while all the pyro-fabricated Ag-Kao nanocomposite samples showed potent antibacterial and antifungal activity at low doses (MIC range 0.1â0.0125 mg/mL). Therefore, modulation of the effective electrostatic surface charge of the kaolinite platelets, via thermal doping of silver within their basal planes and edges, was found to be strongly dependent on the pH as well as the size and microtexture of the silver nanocrystals (mainly controlled by the orderâdisorder degree HI). The resulting modified nanostructure, with physicochemical stability and the efficient surface properties of the designed pyro-fabricated nanocomposite, led to an enhanced synergistic biophysical antimicrobial activity
Enhanced antimicrobial activity and physicochemical stability of rapid pyro-fabricated silver-kaolinite nanocomposite
The present research aims to enhance the antimicrobial activity of kaolinite surfaces by a one-step cost-effective and energy-efficient dry thermal reaction, producing an antibacterial and antifungal silver-kaolinite (Ag-Kao) nanocomposite agent. Pharmaceutical grade kaolin powder samples, with variable kaolinite structural orderâdisorder degree, were homogeneously mixed with silver nitrate in a proportion 1:4 AgNO:kaolin (w/w) and sintered at 400 °C for 30 min. The composition, microstructure, microtexture and surface characteristics of the pyro-fabricated nanocomposites were characterized by XRD/XRF diffractometry, differential scanning calorimetry DSC, FT-IR spectroscopy, TEM/EDX, zeta potential (mV) measured within the 2â12 pH range, and BET method. Physicochemical stability was evaluated by silver dissociation testing under close-neutral and acidic conditions with Ag content assay using ICP-OES. The resulting Ag-Kao nanocomposites exhibited bulk silver contents ranging from 9.29% to 13.32% with high physicochemical stability in both neutral and acidic mediums (Ag dissociation rate 1) produced platelet edge-clustered silver nanocrystals due to the abundance of the dangling hydroxyls on platelet edges, while the highly disordered kaolinite (HI < 1) provided homogeneous platelet basal-doped silver nanocrystals due to the presence of some residual charges by exposed basal hydroxyl groups with interplatelet silver diffusivity. At pH 2, the magnitude of the positive surface charge was influenced by the silver nanocrystal size. Nanocomposites with the smallest silver nanocrystals (10â5 nm) exhibited the highest positive zeta potential (+15.2 mV to +17.0 mV), while those with larger silver nanocrystals (up to 30 nm) indicated lower positive zeta potential values (+9.5 mV to +3.6 mV). Under the same testing conditions using the Mueller-Hinton broth microdilution method, the raw kaolin samples did not show any significant antimicrobial activity, while all the pyro-fabricated Ag-Kao nanocomposite samples showed potent antibacterial and antifungal activity at low doses (MIC range 0.1â0.0125 mg/mL). Therefore, modulation of the effective electrostatic surface charge of the kaolinite platelets, via thermal doping of silver within their basal planes and edges, was found to be strongly dependent on the pH as well as the size and microtexture of the silver nanocrystals (mainly controlled by the orderâdisorder degree HI). The resulting modified nanostructure, with physicochemical stability and the efficient surface properties of the designed pyro-fabricated nanocomposite, led to an enhanced synergistic biophysical antimicrobial activity.This research was supported by the Egyptian Cultural Affairs and Missions Sector (Plan number 7: 2012/2017), Ministry of Higher Education; Group CTS-946 (Junta de AndalucĂa, Spain); MINECO project (CGL2016-80833-R); Erasmus + KA1 mobility program 2016/2017; and the Ministry of Education, Science and Technological Development, Republic of Serbia. The first author is very grateful to Mrs. NataĆĄa StojkoviÄ (Department of Microbiology), Mrs. Biljana MihailoviÄ and Dr. Vladimir DobriÄiÄ (Department of Pharmaceutical Chemistry) of the Faculty of Pharmacy, University of Belgrade, Serbia for their technical assistance
Impact of DEMs for Improvement Sentinel 2 Lithological Mapping Utilizing Support Vector Machine: A Case Study of Mineralized Fe-Ti-Rich Gabbroic Rocks from the South Eastern Desert of Egypt
Fused remote sensing datasets have greatly contributed to enhancing lithological targets and providing significant information for mineral exploration. For instance, multispectral datasets can discriminate rock units through their unique spectral signatures. Digital Elevation Models (DEMs) could be an effective tool boosting lithological discrimination based mainly on their topographic variations. Consequently, the current study applied the power of the support vector machine (SVM) algorithm and the integrated Phased Array L-type band Synthetic Aperture Radar (PALSAR) DEM and multispectral Sentinel 2 data to: 1âCreate an updated lithological map of a poorly mapped arid terrain (Khashir-Ras El-Kharit district, Eastern Desert of Egypt), and 2âCompare and assess the distribution of ferrogabbros with the aim of improving the localization of these rock bodies and investigating their mineral content. Our results enhanced the lithological mapping and revealed a better generalization of mineralized ferrogabbros when the input was a fused DEM with Sentinel 2 compared to the salt and pepper effect observed when adopting the Sentinel 2 solely as the input data. Additionally, the current research strongly recommends detailed exploration programs for Fe-Ti oxide ores within the gabbroic rocks delineated through the resultant thematic map. The ferrogabbros were subjected to a comprehensive analysis involving whole rock geochemistry, XRD, EDX, and light-reflecting investigations, which revealed the existence of magnetite, titanomagnetite, and hematite. The titanomagnetite crystals display subhedral morphology and exhibit fine- to medium-grained surfaces with irregular shapes. X-ray diffraction (XRD) analysis revealed the presence of magnetite and hematite in the concentrated Fe-Ti oxides. Additionally, the whole rock geochemistry highlighted the origin of the ferrogabbros and their proposed tectonic setting as an alkaline to calc-alkaline magma type that developed in a continental arc setting
Multiscale mineralogical investigations for mineral potentiality mapping of Ras El-Kharit-Wadi Khashir district, Southern Eastern Desert, Egypt
Through various scales of observation, ranging from remote sensing data, field investigations, hand specimens, microscopic petrographic examinations, XRD, to SEM, indicators of various mineralization types are highlighted in Ras El-kharit-wadi Khashir (Eastern Desert, Egypt). Systematic remote sensing exploration of the mineralized zones is performed through integrating Sentinel 2 and ASTER datasets. False-color combinations, informative band ratios, relative absorption band depth, and CEM techniques were applied to discriminate rock units and various types of hydrothermal alterations. Moreover, ALOS PALSAR DEM was utilized to decipher the structural lineaments. Intensive field investigations confirmed hydrothermally altered zones that were picked out through remote sensing analysis and revealed that the study area is affected by cataclastic metamorphism to some extent. Magmatic and metamorphic rock types are represented by propylitic, phyllic, argillic, and silicification zones. Sericitization, chloritization, epidotization, kaolinitization, carbonatization, and silicification are recorded utilizing petrographic and remote sensing investigations. Moreover, the current study reveals that the detected alteration is the main reason for the apparent wide range of petrographic characteristics of each rock type and bearing several opaque minerals, such as pyrite, magnetite, titanomagnetite, chalcopyrite, arsenopyrite, covellite, galena, goethite, and hematite. Most of these opaques were identified using ore microscopy, XRD, and SEM. The distribution of hydrothermal alterations, representative samples bearing mineralization, structurally dissected zones are integrated to build a mineral potentiality map of the study area. The resultant MPM was confirmed via field survey and emphasized the usefulness of the current integrated approach besides highlighting about 125Â km2 as potential mineralized zones
Kaolinite in pharmaceutics and biomedicine
Kaolinite has been used in many pharmaceutical applications as excipient or active ingredient, because it
exhibits excellent physical, chemical and surface physicochemical properties. In addition to their classical
pharmaceutical uses, kaolinite and its derivatives have been recently considered as a promising material in many
biomedical innovation areas such as drug, protein and gene delivery based on the high interaction capacities
with organic and biochemical molecules, bioadhesion and cellular uptake