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Abdel-Khalek A.A.,Beni Suef University | Ali M.M.,Nuclear Material Authority | Hussein A.E.M.,Nuclear Material Authority | Abdel-Magied A.F.,Nuclear Material Authority
Journal of Radioanalytical and Nuclear Chemistry | Year: 2011

Extraction of uranium from Egyptian phosphoric acid with synergistic mixture of di-2-ethylhexylphosphoric acid (D2EHPA) and di-butyl butyl phosphonate (DBBP) is reported in this paper. The influence of various factors such as D2EHPA concentration, DBBP concentration, phosphoric acid concentration, contact time, aqueous: organic phase's ratio (aq:org) and temperature on the degree of extraction has been established. The data on the effect of temperature on the extraction showed that the enthalpy change is -23.12 kJ/mol. Uranium extracted by D2EHPA-DBBP is further subjected to a second cycle of extraction and scrubbing impurities. The uranium is finally converted to a high purity UO 3 product using precipitation with hydrogen peroxide and heat treatment at 375 °C. © 2011 Akadémiai Kiadó, Budapest, Hungary.

Ali K.A.,King Abdulaziz University | Ali K.A.,University of Texas at Dallas | Moghazi A.-K.M.,King Abdulaziz University | Moghazi A.-K.M.,Alexandria University | And 7 more authors.
International Journal of Earth Sciences | Year: 2012

The Humr Akarim and Humrat Mukbid plutons, in the central Eastern Desert of Egypt, are late Neoproterozoic post-collisional alkaline A-type granites. Humr Akarim and Humrat Mukbid plutonic rocks consist of subsolvus alkali granites and a subordinate roof facies of albite granite, which hosts greisen and Sn-Mo-mineralized quartz veins; textural and field evidence strongly suggest the presence of late magmatic F-rich fluids. The granites are Si-alkali rich, Mg-Ca-Ti poor with high Rb/Sr (20-123), and low K/Rb (27-65). They are enriched in high field strength elements (e. g., Nb, Ta, Zr, Y, U, Th) and heavy rare earth elements (La n/Yb n = 0. 27-0. 95) and exhibit significant tetrad effects in REE patterns. These geochemical attributes indicate that granite trace element distribution was controlled by crystal fractionation as well as interaction with fluorine-rich magmatic fluids. U-Pb SHRIMP zircon dating indicates an age of ~630-620 Ma but with abundant evidence that zircons were affected by late corrosive fluids (e. g., discordance, high common Pb). εNd at 620 Ma ranges from +3. 4 to +6. 8 (mean = +5. 0) for Humr Akarim granitic rocks and from +4. 8 to +7. 5 (mean = +5. 8) for Humrat Mukbid granitic rocks. Some slightly older zircons (~740 Ma, 703 Ma) may have been inherited from older granites in the region. Our U-Pb zircon data and Nd isotope results indicate a juvenile magma source of Neoproterozoic age like that responsible for forming most other ANS crust and refute previous conclusions that pre-Neoproterozoic continental crust was involved in the generation of the studied granites. © 2012 Springer-Verlag.

Mahmoud M.A.,Nuclear Material Authority | Mahmoud M.A.,Jazan University
Journal of Saudi Chemical Society | Year: 2016

The adsorption kinetics for removal of uranium (V1) from aqueous solution using silicon dioxide nanopowder (nano-SiO2) was investigated in batch and continuous techniques. Pseudo-first order and pseudo-second order were used to analyze the kinetics of batch experiments. In continuous technique the important parameters (initial concentration, flow rate and bed height) on the breakthrough curves were studied and the adsorption kinetics was analyzed using Thomas and Yoon and Nelson kinetic models. The comparison between the kinetic models was evaluated by the correlation coefficients (r 2). The results indicated that the batch experiments fitted well with pseudo second-order kinetic model. The comparison of the experimental breakthrough curve to the breakthrough profile obtained from Thomas and Yoon and Nelson methods showed a satisfactory fit for silicon dioxide nanopowder. © 2016 King Saud University.

Salman A.B.,Nuclear Material Authority | Howari F.M.,University of Texas of the Permian Basin | El-Sankary M.M.,Nuclear Material Authority | Wali A.M.,Cairo University | Saleh M.M.,Cairo University
Journal of African Earth Sciences | Year: 2010

Kharga Oasis monumental sites are important to the cultural heritage in the South Western Desert of Egypt. These sites are scattered on the floor of the oasis representing ancient civilizations. The studied sites include the Hibis, EI-Nadura, EI-Ghueita and El-Zayyan temples as well as El-Bagawat Cemetery. The present study found that natural hazards have remarkable impacts on these sites. The impact of weathering processes, encroachment of sand dunes, stability of foundation beds and shallow groundwater seepage were documented. The present study found that humidity, temperature, sunlight and water content conditions seem to be favorable for biodegradation as evidenced by the presence of algae, bat blood and bird excretions. The radioactivity levels at the investigated sites are also measured via gamma-ray spectrometry.Sand dunes in the area pose a serious natural threat to the monumental sites. Active sand dunes are rapidly encroaching upon the components of these monuments, partially covering some monuments such as El-Ghueita Temple. These dunes load wind storms with fine sand particles. This causes wind erosion through sand blasting of these sites. Some monuments, such as EI-Nadura, EI-Ghueita and El-Zayyan temples were constructed on a suitable hard sandstone ground, whereas others, such as the Hibis Temple, were constructed on unsuitable soft shale ground in relatively topographically low area. The impact of the unstable foundation and shallow groundwater levels have caused severe structural damage as evidenced by tilted columns, cracked walls and salt-crystal growth in the porous building stones. These destructive elements threaten some other temples in Kharga Oasis and will eventually cause total physical collapse. Although rain is rare in this area, it can form a real threat to mud brick monuments such as El-Bagawat Cemetery. The natural radioactivity sources resulted in an annual effective dose equivalent values averaging 0.20, 0.13, 0.09 and 0.07. mSv/year for the monumental sites at Hibis, El-Nadura, El-Ghueita and El-Zayyan, respectively. © 2010 Elsevier Ltd.

Mahmoud M.A.,Nuclear Material Authority | Mahmoud M.A.,Jazan University
Journal of Environmental Chemical Engineering | Year: 2015

Abstract Sorption of uranium(VI) from aqueous solution onto powdered corn cob has been carried out using batch technique. The maximum removal (98.5%) was obtained at pH 5 and contact time 60 min. Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherms are used for describing the sorption process. It is found that the Langmuir isotherm appears to be the best fitting model and pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion kinetics models were studied. The results indicate that the process follows the pseudo-second-order kinetics model. As well as the thermodynamic data indicate that the sorption processes is exothermic. The values of enthalpy (ΔH°), mean free energy (E) and activation energy (Ea) indicate that the sorption process is physical sorption. A single stage of batch adsorber has been designed for various volumes using the Langmuir isotherm. © 2015 Elsevier Ltd.

Mahmoud M.A.,Nuclear Material Authority | Mahmoud M.A.,Jazan University
Process Safety and Environmental Protection | Year: 2016

Aluminum oxide nanopowder (AONP) was used for the preconcentration and recovery of uranium ions from an aqueous solution. Adsorption process in batch system was carried out by varying pH, initial U(VI) concentration, adsorbent dose, adsorption time and temperature. The adsorption efficiency could reach 99.85% at pH 5.0, 150 mg dose and 303 K. Desorption of uranium ions can be carried out using 1.5 M HNO3. Equilibrium adsorption was attained within 40 min at 303 K and within 20 min at 333 K indicating that the rate of U(VI) uptake was found to be faster with increasing temperature. Adsorption data indicates the process following Langmuir isotherm and pseudo-second-order kinetic model. The mean energy, enthalpy, and activation energy confirming that the adsorption of U(VI) onto AONP is physical adsorption. Moreover, the thermodynamic parameters showed the endothermic and spontaneous nature of the adsorption process. © 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Mohammed H.,Nuclear Material Authority | Sadeek S.,Zagazig University | Mahmoud A.R.,Nuclear Material Authority
Microchemical Journal | Year: 2016

Uranium and thorium have been measured in oil ash samples collected from four Egyptian power plants that use heavy fuel oil. The U and Th content in oil ashes was determined by INAA, ICP-MS, ICP-OES, WDXRF, and EDXRF without any sample pretreatment. Samples were digested using two acid, four acid, or fusion method. The concentration of U and Th were found to be within the average worldwide value. Uranium and thorium content in heavy fuel oil were also measured for the first time. For quality control of the analytical data, three internal reference materials were prepared and used. © 2015 Elsevier B.V.

Howari F.,Zayed University | Goodell P.,University of Texas at El Paso | Salman A.,Nuclear Material Authority
Journal of African Earth Sciences | Year: 2016

This paper is briefly involved in classification and distributions of the Middle East and North Africa (MENA) uranium deposits. The study of these mineral systems can significantly contribute to our further understanding of the metallogeny of known and poorly explored deposits. This provides contribution to, and further enhancement of, current classifications and metallogenic models of uranium systems, allowing researchers to emphasize on unknown or poorly studied mineral systems found in MENA. The present study identified eight metallogenic types of uranium associated with: 1) the Archean rocks and intra-cratonic basins, 2) the Pan-African granites and rhyolites which are characterized by igneous activity, 3) Phanerozoic (Paleozoic) clastics, these deposits are the sedimentological response to Pan African magmatism, 4) Mesozoic (basal) clastics type e.g. Nubia sandstones which are characterized by uranium minerals, 5) regional sedimentary phosphate deposits which are categorized as geosynclinal, or continental margin deposits, on the shelf of the Tethys Ocean, 6) Cenozoic Intracratonic Felsic Magmatism of the Tibesti and Hoggar, and the sandstone U deposits of adjoining Niger. These are similar to the Pan-African magmatism metallogenic, 7) Calcretes, and 8) Resistate minerals which are often enriched in rare earth elements, sometimes including uranium. They are thus sometimes considered as U resources but poorly explored in the MENA region. These metallogenic types are described and discussed in the current paper. © 2015 Elsevier Ltd.

Osman R.A.,Nuclear Material Authority | Mahmoud M.A.M.,Nuclear Material Authority
Arabian Journal of Geosciences | Year: 2014

The Um Ghannam area lies within the core of Hafafit Complex, South Eastern Desert. This area is occupied mainly by granitic gneiss (orthogneiss). However, the granitic gneiss is extruded by swarm metarhyolite dykes and quartz veins. The studied metarhyolite dyke is classified into two distinctive zones. However, the intense degree of hydrothermal alteration can partition this dyke into weakly and extremely altered zones. According to the extraordinary diversity in color, this dyke is distinguished into gray to dark gray (weakly altered) and greenish (extremely altered) metarhyolite. Petrographical, mineralogical, and geochemical characteristics of the two distinctive zones are detected in a representative sample. Petrographically, the weakly altered zone is mainly represented by chloritization of primary biotite, garnet, and epidote, and argillitization of primary plagioclase. Although the extremely altered zone contains intensely altered remnants of the original rock, the extremely altered zone is distinguished by intense oxidation products (carbonate minerals and quartz, with significant amounts of secondary Cr-muscovite and hematite). The mineralogical studies are imposed on the millimeter and the micrometer scale in this important hydrogeothermal system. Except for Ca and Mg, most of the major elements are depleted at the extremely altered zone. However, the extremely altered zone is enriched in trace elements (Cr, Mn, Co, and Ni). The major elements of the extremely altered zone reflect the significant alterations (desilication, muscovitization, and carbonatization). These alteration processes have taken place in the hydrogeothermal system in the extremely altered zone. The geothermal fluid is responsible for these hydrothermal alterations. High fO2 and high temperature are characteristic features of this fluid. Then, the high-field-strength elements such as Zr, Ti, and P are depleted as a significant hydrothermal alteration. Also, nuclear elements with the anion of (CO3)2- can travel as molecular complexes (carbonates), as long as the chemical and structural conditions are suitable for the movement of these elements from the metarhyolite dyke to redeposit and accumulate in another geologic formation. The rare earth elements La and Ce, as well as Yb and Lu, are partially mobilized during intensity alterations. The rare earth elements (REEs) are depleted in abundance with enrichment of CO2 from the weakly altered zone to the extremely altered zone. The REE budget is decreased from the weakly altered zone to the extremely altered zone as 121.17 to (27.38 - 16.52), respectively. The significant depletion of ∑REEs is controlled by dissolution of monazite. Monazite breakdown and even apatite formation can be caused by alkaline fluid. This fluid is related to event and thermal stage. However, the negative anomaly of Eu can be noticed in all studied samples. Then, Eu anomaly may be formed from plagioclase fractionation. The weakly altered metarhyolite zone and orthogneiss have lower HREE/LREE (0.07-0.11), respectively, relative to the extremely altered metarhyolite zone (0.17 - 0.2). Even all studied samples at two significant zones are characterized by the enrichment of ∑LREEs relative to ∑HREEs. © 2013 Saudi Society for Geosciences.

Jamil T.S.,National Research Center of Egypt | Ghaly M.Y.,National Research Center of Egypt | Fathy N.A.,National Research Center of Egypt | Abd El-Halim T.A.,Nuclear Material Authority | Osterlund L.,Swedish Defence Research Agency
Separation and Purification Technology | Year: 2012

The activated carbon loaded TiO 2 photocatalyst was prepared and characterized by FT-IR, scanning electron micrograph (SEM) and X-ray diffraction (XRD). The photocatalytic efficiency of activated carbon loaded TiO 2 was evaluated by photocatalytic oxidation of Methyl Orange (MO) dye in aqueous medium using visible and solar light. TiO 2/AC exhibited higher photocatalytic oxidation efficiency of MO than that of naked TiO 2. The various experimental parameters like initial dye concentration, amount of catalyst and solution pH for efficient dye degradation are investigated. Activity measurements performed under visible light and solar irradiation have shown good results for the photo degradation of MO in aqueous solution. The higher efficiency of TiO 2/AC is due to synergy effect of activated carbon. Addition of high adsorption capacity activated carbon to photoactive titanium dioxide in photocatalytic degradation of dyes improves the efficiency of dye mineralization. The present catalysts show high adsorptivity and high photoactivity for the degradation of the MO dye and can be very easily separated from the solution by sedimentation or simple filtration and it can be used repeatedly for MO removal with preservation of its photoactivity. © 2012 Elsevier B.V. All rights reserved.

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