Ezzat A. Ahmed

Superior removal of Co 2+ , Cu 2+ and Zn 2+ contaminants from water utilizing spongy Ni/Fe carbonate–fluorapatite; preparation, application and mechanism

Spongy Ni/Fe carbonate - fluorapatite was synthesized from natural phosphorite enriched with iron impurities. The morphological, chemical and structural features of the product were estimated using several techniques as XRD, SEM, EDX, and FT-IR. It exhibits spongy structure of nano and micro-pores. The average crystallite size is about 8.27 nm. The suitability of the product for considerable decontamination of Zn2+, Co2+, and Cu2+, ions from water was studied based on several reacting parameters. The equilibrium was attained after 240 min for Zn2+ and Co2+ ions while the adsorption equilibrium of Cu2+ reached after 120 min. The adsorption data for the selected metals was represented well by a pseudo-second-order model which revealed chemisorption uptake. The equilibrium studies were appraised based on traditional models and two advanced models were designed according to the statistical physical theories. The adsorption results highly fitted with Langmuir model followed rather than the other models. This indicated a monolayer adsorption for the metal ions by spongy Ni/Fe carbonate - fluorapatite. The estimated qmax values are 149.25 mg/g, 106.4 mg/g and 147.5 mg/g for the uptake of Zn2+, Co2+, and Cu2+, respectively. Based on monolayer models of one energy and two energies, the number of receptor adsorption sites, number of adsorbed metal ions per active site, the average number of sites which occupied by ions, mono layer adsorption quantity and the adsorption quantity after total saturation were calculated for the first time for such materials.

Sedimentological, mineralogical and geochemical studies on some recent Khors sediments, Lake Nasser, Egypt

Abstract Sixty-six bottom samples were collected from Khor El-Ramla, Khor Kalabsha, Khor Wadi-Abyad and Khor Allaqi of Lake Nasser. Variations in their grain-size parameters are attributed to the characteristics of the surrounding Precambrian basement rocks and Upper Cretaceous Nubia Sandstone. The quartz surface texture reflects fingerprints of the original aeolian environment of some grains in spite of the diagenesis effect. The heavy mineral suite illustrates the prime control of provenance. The clay fraction is composed mainly of kaolinite and smectite. Illite occurs in traceable amounts. Their distributions suggest a detrital origin. Geochemical analysis of the clay fraction for SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, K 2 O, Ni, Cu, Pb and Mn content was carried out.

Cosmetic and pharmaceutical qualifications of Egyptian bentonite and its suitability as drug carrier for Praziquantel drug

Abstract The aim of this paper is to characterize and evaluate newly discovered bentonite deposits in Egypt for pharmaceutical and cosmetic applications as well as its suitability as carrier for Praziquantel drug. The study was performed for the raw bentonite sample, purified bentonite sample and alkali activated purified bentonite sample. The raw bentonite sample composed mainly of montmorillonite contaminated by little amounts of quartz and calcite, while the purified sample composed of montmorillonite without detected mineral impurities and matches the mineralogical properties of Wyoming bentonite as an international standard. Geochemically, the studied raw and purified samples appear to high purity with a chemical composition close to those of Wyoming bentonite and match the pharmacopeia specifications. The chemical properties in addition to the textural properties of the surface area, porosity, particle size distribution qualify the bentonite products to use as a function in powder, emulsion and creams. Investigation of pharmacopeia properties of pH, sedimentation volume and swelling capacity revealed the suitability of the raw and purified samples for pharmaceutical and cosmetic applications. Moreover, the microbiological tests indicated that the samples free from harmful microbial pathogens. At the optimum conditions of time (240 min), bentonite dose (250 mg) and reaction temperature (60 °C), the obtained encapsulation percentages of Praziquantel drug are 62%, 78.4% and 93.2% for raw bentonite, purified and alkali activated bentonite, respectively. The releasing percentage of the drug using an intestinal buffer at pH 7.4 is more efficient and the maximum obtained values were obtained after 420 min. The obtained releasing values are 71%, 79.2% and 87.4% for raw bentonite, purified bentonite and alkali activated bentonite, respectively Graphical Abstract Figure. No caption available.

Quartz surface textures of some cretaceous Nubian sandstone exposures, Central Eastern desert, Egypt

Abstract The common and dominant surface features observed in the quartz grains of the Nubia Sandstone encompass both mechanical and chemical features. Such features point to a complex depositional history of the Nubia Sandstone including deposition by aeolian processes followed by fluvial sedimentation. Diagenesis in the Nubia Sandstone is represented by silica precipitation and dissolution.

Aquifer recharge, depletion, and connectivity: Inferences from GRACE, land surface models, and geochemical and geophysical data

Data from the Gravity Recovery and Climate Experiment (GRACE) and outputs of the CLM4.5 model were used to estimate recharge and depletion rates for large aquifers, investigate the connectivity of an aquifer’s subbasins, and identify barriers and preferred pathways for groundwater flow within an aquifer system. The Nubian Sandstone Aquifer System and its subbasins (Dakhla, Northern Sudan Platform, and Kufra) in northeast Africa were used for demonstration purposes, and findings were tested and verified against geological, geophysical, remote sensing, geochronologic, and geochemical data. There are four major findings. (1) The average annual precipitation data over recharge areas in the southern Kufra section and the Northern Sudan Platform subbasin were estimated at 54.8 km 3 , and 32.8 km 3 , respectively, and knowing the annual extraction rates over these two areas (∼0.40 ± 0.20 km 3 ), recharge rates were estimated at 0.78 ± 0.49 km 3 /yr and 1.44 ± 0.42 km 3 /yr, respectively. (2) GRACE-derived groundwater depletion rates over the Dakhla subbasin and the Northern Kufra section were estimated at 4.44 ± 0.42 km 3 /yr and 0.48 ± 0.32 km 3 /yr, respectively. (3) The observed depletion in the southern parts of the Dakhla subbasin is apparently caused by the presence of the east-west−trending Uweinat-Aswan basement uplift, which impedes the south-to-north groundwater flow and hence reduces replenishment from recharge areas in the south. (4) A major northeast-southwest−trending shear zone (Pelusium shear system) is apparently providing a preferred groundwater flow pathway from the Kufra to the Dakhla subbasin. Our integrated approach provides a replicable and cost-effective model for better understanding of the hydrogeologic setting of large aquifers worldwide and for optimum management of these groundwater resources.

Mid-Paleocene event at Gabal Nezzazat, Sinai, Egypt: planktonic foraminiferal biostratigraphy, mineralogy and geochemistry

The Qreiya Beds that record the ‘mid-Paleocene event’ at Gabal Nezzazat occur within the Igorina albeari (P3b) Zone and constitute part of a 14-m thick shale succession that ranges in age from Early to Late Paleocene. They are composed of four alternating dark grey and brown shale beds, which are thinly laminated, phosphatic, organic-rich and extremely sulphidic. They are characterized by distinct enrichment and high peak anomalies in chalcophiles (Zn, Co, Ni, Cu and Pb) and organic association elements (V and Cr), especially within the brown organic-rich beds. It is concluded that these elements are incorporated into the phosphatic debris, sulphides and organic matter. In contrast, the grey beds are enriched in clay minerals and quartz. Clay mineral assemblages indicate alternating periods of warm/humid climate (high kaolinite) and dry climate (low kaolinite) during the formation of the grey and brown beds, respectively. The sediments of the Qreiya Beds yield lithological, biotic, geochemical and mineralogical data indicative of suboxic/anoxic marine environments as a result of high productivity and/or upwelling. The top metre of the succession below the Qreiya Beds is characterized by a progressive change from faunas dominated by praemurcurids to faunas dominated by Morozovilids, and by a progressive upward decrease in δ13Ccarb and δ18Ocarb values. The foraminiferal faunal change may reflect shallowing and warming preceding deposition of the Qreiya Beds. The change in isotopic values is inferred to be the result of surface weathering, fluvial input and diagenesis with no evidence of any primary change that could support presence of a hyperthermal event.

Facies control on the distribution of some trace and rare earth elements in Egyptian phosphorites

Abstract The distribution of some trace and rare earth elements in phosphorite samples from the Red Sea area, the Nile Valley and the Western Desert of Egypt is described in this paper. The phosphorites are interbedded with siliciclastic and/or carbonate facies. Elements such as Sc, As and Sr are concentrated in the phosphorites associated with the c siliciclastic facies, whereas Cr, V, Zn, Sb, I, Ba, U and Th are enriched in the phosphorites associated with the carbonate facies. Shale-normalized rare-earth element pattern for the Abbu Tartuir and Yunis phosphorites are similar to those reported for shale, while phosphorites interbedded with the carbonate facies (Wadi Abu Hamra, Abu Shgeili, Queih, Nasser, Duwi together to those of the Nile Valley) show a sea water pattern.

A conceptual phosphogenesis model for the Red Sea phosphorites, Quseir area, Egypt

Along the Red Sea coast (at Quseir area), the Upper Cretaceous-Lower Paleogene phosphorite-bearing sediments were laid down under shallow marine conditions. There, thick economic phosphorite beds are intercalating the Quseir, Duwi, and Dakhla formations. Furthermore, thin phosphorite beds (< 20-cm thick) have been recorded as interbeds within the above-mentioned rock units. Each high-grade, economic phosphorite bed experienced many successive stages of phosphogenesis. The initial stage of phosphogenesis started with scattered phosphate peloids, which accumulated below fair-weather wave base and under calm conditions. Subsequently, the frequency and quantities of these peloids increased with time. The closing session of the phosphogenesis scenario was characterized by exhumation, fragmentation, and redeposition of the peloids by high-energy episodes (i.e., storms). Prolonged action of these high-energy events resulted in mixing of peloids with other phosphatic components in crudely fining upward sequences. Both one-event and amalgamated (multi-event) storm beds are common. The SEM investigations have indicated that algal blooms played a vital role in the origin of the Red Sea phosphorites. These algal blooms acted as important sites for P fixation and consequently, a release of P. Integrated field and laboratory studies have revealed that phosphorite rocks display noticeable variations from one locality to another. These variations include changes in thickness, P2O5 content and the hosting sediments (siliciclastics and/or carbonates). A plausible explanation for these variations may be related to the effect of synsedimentary local tectonics.