Search

Variable single and/or swarms of post-granitic dikes are widespread at Gabal Serbal, Southwestern Sinai, Egypt. The present article aims to identify and discriminate these multiphase dikes through detailed geological, petrographical, and geochemical examinations. These dikes are classified into two subphases: (1) acidic dikes (porphyritic dacite, microgranite, granophyre, and alkaline granophyre dikes); and (2) basic dikes (basalt and dolerite dikes). They range from vertical or steeply inclined bodies, 0.5–15 m wide, pink to black color, and NE–SW to N–S directions. Acidic dikes with different mineralogical constituents have medium to high k-characters, originating from calc-alkaline magma and extruded in a volcanic arc environment. In contrast, basic dikes have medium k-characters, originating from tholeiitic magma and developing within a plate environment. Basic dikes are enriched with opaque minerals, where the basaltic dike contains iron oxides (magnetite and hematite), such as apatite in addition to copper minerals. Dolerite dike comprises magnetite, titanomagnetite, and pyrite.

Radiological hazards of natural radionuclides in eleven sedimentary rocks samples, collected from southwestern Sinai, were investigated. The activity concentrations were measured using HPGe detector. The average values of 238U, 235U, 234U, 226Ra, 232Th, and 40K were 5456 ± 35, 250 ± 4.50, 4853 ± 68, 5194 ± 17, 60 ± 2.62 and 553 ± 14 Bq kg−1, respectively. The hazard indices including radium equivalent, gamma index, internal health hazard, the absorbed gamma dose rate, annual effective doses and excess lifetime cancer risk were evaluated. The results demonstrated high concentrations of the natural radioactivity and the associated hazard indices.

The exposures of the lower member of Um Bogma Formation (Early Carboniferous) in a vast area east of Wadi Baba were studied in six localities. The member is dominated by argillaceous rocks in the w...

High-level natural radioactivity, geochemical, geological, and radiological hazard assessment of the poorly investigated Wadi Gebeiy Dokhan volcanics rocks are discussed. Wadi Gebeiy Dokhan volcanics are located in Southwestern Sinai, Egypt, covering an area of ~1.3 km2. Dokhan volcanics rocks are represented by porphyritic dacite. Geochemically, they have medium-k characters and originate from calc-alkaline magma within a volcanics arc environment. Along the fault plane striking NNE-SSW, and at its intersection with the NW-SE fault plane, altered Dokhan volcanics occur with high radioactive anomalies. Radiological parameters (absorbed dose rate, radium equivalent, activity annual effective dose, external and internal hazard indices) are used to evaluate their suitability as an ornamental stone. Except for the absorbed dose rate, all the radiological hazard indices show that unaltered Dokhan volcanics can be used as an ornamental stone. Controversially, the applied radiological indices reveal that altered Dokhan volcanics have a higher content than the recommended values of UNSCEAR, reflecting their risk on human organs. © 2022 by the authors. H.M.H.Z. is funded by a scholarship under the Joint Executive Program between Egypt and Russia.

International audience; A new sorbent was designed by functionalization of a bio-based composite made of chitosan and Arabic gum. The grafting of two sulfonate-bearing moieties allows reaching, at the optimum pH (i.e., pH0 4), a sorption capacity as high as 1.48 mmol U g−1 (with strong affinity; bL being close to 356 L mmol−1). The Sips equation fits better sorption isotherms than the Langmuir equation. The maximum sorption capacity increases with temperature (while the affinity coefficient does not follow a continuous trend). The sorption kinetics are very fast; 20 min of contact are sufficient for reaching the equilibrium and the kinetic profiles are successfully fitted by the pseudo-first order rate equation. HCl solutions (0.2 M) are highly efficient for completely desorbing bound uranyl ions; the loss in sorption efficiency does not exceed 3% after 5 re-use cycles. At pH above 4, the sorbent shows high selectivity against Ca(II), Mg(II), Al(III) and Zn(II) (against Fe(III) and Cu(II), to a lesser extent). The sorbent is successfully tested for the decontamination of water samples collected from five wells located in Sinai (Egypt): uranium removal approaches 100%; metal ions like Cu(II), Fe(III), Zn(II) and Pb(II) are also remarkably recovered from samples at pH0 5.5. Complementary tests (using agar well diffusion method) show that the sorbent brings an additional antimicrobial activity against S. aureus, B. subtilis, E. coli, P. aeruginosa, and C. albicans, with MIC values ranging between 50 and 25 µg mL−1. The sorbent is characterized by negligible toxicity, using the MTT assay method against two normal cell lines (i.e., Vero and HFB4), and a cancerous cell line (i.e., Caco-2).

This research focused on studying the effect of sulfuric acid concentrations on the leaching of different radionuclides (238U and 235U series) in two samples (high- and low-grade). The activity concentrations of radionuclides in the uranium series (238U and 235U) were measured by an HPGe detector. The leaching efficiency of 238U and 235U series was different in the samples and the leaching percent of 230Th was the highest in the samples, which may be due to the presence of the organic matter. There are radioactive disequilibria between 238U, 234U and 230Th in leachate and residual phase due to redistribution between acid-soluble and acid-resistant phases.

Soil is a source of natural radionuclides and a source of natural radiation risk to humans. This study aims to measure the radioactivity concentrations, contributions, radiological hazards and to quantify the radiogenic heat productions in thirty two rock samples having different lithology from the middle member of Um Bogma Formation in Gabal Um Hamd, southwestern Sinai, Egypt. The concentration of natural radionuclides was determined using a p-type Hyper Pure Germanium (HPGe) detector. The average activity concentrations of uranium U 238 , radium R 226 a , thorium T 232 h , and potassium K 40 in the interested area were found to be 4909.58 ± 54.34 B q k g − 1 , 5003.12 ± 17.56 B q k g − 1 , 79.04 ± 8.82 B q kg − 1 and 137.35 ± 8.64 B q kg − 1 respectively. Other hazard indices average values were measured, such as: annual effective dose equivalent, radium equivalent activity, external and internal indices, annual gonad equivalent dose, and excess lifetime cancer risk. The radiologic hazards results, obtained in this study shows that the radiation levels are higher than the internationally approved values and the recommended safety limits. Furthermore, the results show that the radiogenic heat value ranged from 3.58 to 402.45 μW m −3 with an average value of 60.11 ± 0.79μW m −3 in the studied area which is higher than previously reported averages.

Uranium tailings represent a huge radioactive waste contaminant, where radon emanation is considered a major health hazard. Many trials have been conducted to minimize radon exhalation rate by using different covering materials. In the present work, three covering materials, commonly available in the local environment, (kaolin, white sand and bentonite) have been used with different thickness 10, 15, and 20 mm). 238U, 232Th, 40K and the radon exhalation rate were measured by using gamma spectrometry with a Hyper Pure Germanium (HPGe) detector and solid state nuclear track detectors (CR-39). Radon exhalation rate, calculated before and after covering, ranged from 2.80 ± 0.14 to 4.20 ± 0.21 Bq m−2 h−1, and from 0.30 ± 0.01 to 4.00 ± 0.20 Bq m−2 h−1, respectively. Also, the attenuation coefficients of different covering materials and radon emanation were calculated. The obtained results demonstrate that covering of uranium tailings by kaolin, white sand and bentonite has potentially minimized both the radon exhalation rate and the corresponding internal doses.

The upper part of the Adediya Formation (Cambro-Ordivician) exposed in southwestern Sinai represents a very interesting succession. It contains mineralizations which are exceptionally rich in radioactive and rare earth elements as well as heavy metals. Field and several laboratory studies were carried out on this part of the Adediya Formation exposed in four stratigraphic sections distributed in a geographically wide area in southwestern Sinai. The radioactive mineralizations exist in sandstones, ironstone bodies and, to a much lesser extent, siltstones. Each of these rock types has a relatively wide range of textural characteristics. The recorded mineral assemblage consists of a large number of essential and accessory minerals some of which are radioactive and REE-bearing. The obtained field and laboratory data were implemented to determine the sedimentary history of the host rocks and the genesis of the mineral species which constitute the mineralizations. This included the identification of the types and effects of the various diagenetic processes and hydrothermal activity which led to the genesis of the recorded mineralizations. Also, the relative roles played by these post-depositional processes in determining the mineral, chemical and radioactive characteristics of the mineralizations and host rocks were assessed. These roles resulted in redistribution of the various elements especially the radioactive and rare earth elements as well as heavy metals during the epigenetic phase particularly by the action of supergene processes. A genetic model for the studied mineralizations is proposed.

Processed ores may contain substantial amounts of residual valuable metals. In the case of the mining wastes issued from the exploitation of gibbsite bearing shale ore in the Southwestern Sinai, the characterization of the residue shows the presence of uranium, rare-earth elements (REEs), aluminum and zinc that can be valorized. Pug leaching at 120 °C with an acid consumption of about 200 kg H2SO4 per ton of ore succeeded in leaching more than 94% of U(VI) and REEs (in addition to substantial amounts of Al(III) and Zn(II)). A series of selective precipitation steps allowed successively recovering (almost quantitatively) Zn(II), Fe(III) and Al(III). In a second step, a magnetic resin has been used for enriching the pregnant leaching solution (by a factor close to 19) through sorption/desorption steps. In the last stage of the process, REEs were recovered by selective precipitation using 25% (w/w) oxalate solution at pH 1.5, while uranium was fully recovered by precipitation with NaOH at pH 9. Energy dispersive X-ray analysis performed on the different precipitates showed purity grades systematically superior to 93%.

International audience; A magnetic glycine-grafted chitosan sorbent (Gly) was functionalized to produce a hydrazide derivative (HGly). The two sorbents were tested in batch mode for the sorption of a series of 10 metal ions present in the groundwater collected in three wells in the Wadi (valley) Nasib mining area (SW Sinai, Egypt). HGly is much more efficient for metal recovery than Gly. Under selected experimental conditions (sorbent dosage 1.5 g L−1), the sorption efficiency is not sufficient for achieving the standard levels for drinking water: the most problematic metal ions in terms of drinkability remain aluminum (too high metal concentration in the groundwater), cadmium, and chromium for the three wells (and nickel in the case of only one well). Increasing the sorbent dosage improves the treatment efficiency. The sorbent (HGly) was tested in fixed-bed columns. The breakthrough curves were compared for the different metals for the groundwater collected in the most contaminated of the three wells. The levels of metal concentration in the treated groundwater are too high for direct use in irrigation. However, they are consistent with the standards for livestock drinking water (based on FAO recommendations, Food and Agriculture Organization of the United Nations). The metals can be readily desorbed using 0.5 M HCl solutions with a relatively high concentrating effect (i.e., 50 times). The re-use of the sorbent for three successive cycles of sorption/desorption cycles shows a progressive but weak decrease in sorption and desorption performances.

Tailings resulted from sulphuric acid leaching process of uranium from sedimentary rocks contain high concentrations of 226Ra and its daughters, the most important of which is 222Rn. Movement of radon gas out of the tailings is strongly influenced by the physicochemical characteristics of these tailings especially their radium content and the grain size. So, the tailing samples were size fractionated into four sizes (> 250, 250–125, 125–74 and 250 and

Water from well in Wadi Naseib is contaminated with uranium (4 mg/l). The maximum uranium concentration in drinking water is 0.009 mg/l as assigned by World Health Organization in 1998, thus this water increases drinking water limit nearly 500 times. It is characterized by high concentrations of carbonaceous matters and heavy metal ions reflecting the geochemical characterization of the surrounding rocks of black shale and dolomite. Removal of uranium was performed using commercial and synthetic adsorbents with respect to its effect on human health. Resins used were DOWEX 21K 16/20 type (commercial resin) and polyacrylamidoxime acrylic acid divinylbenzene PAm/AA (synthetic resin). DOWEX 21K 16/20 type is suited for mineral processing and groundwater remediation applications. PAm/AA has high capacity and selectivity for uranium and recovered it from low grade solutions. It was safe and suited for groundwater treatment.

It is very difficult to recover uranium and rare earth elements (REEs) from low-grade ore especially gibbsite-bearing shale. The difficulty lies not only in the separation of uranium from REEs, but also the very low concentration of uranyl ions and REEs comparison with other metal ions in liquor. In this study, we perform the recovery in three steps. In the first step, involves the chelating resins are synthesized. The second step, then, involves the leaching of the ore sample (leach liquor), which can be performed by two methods—direct agitation and column leaching, whichever the most efficient under stated conditions. A sulfuric acid solution was used, with different concentrations of 0.5–3.0% (W/W) with different solid liquid ratios (S/L) of 1:2 to 1:5. The effect of the leaching time was calculated and the optimum condition of agitation was determined. In the third and last step, the leach liquor is applied to the choice synthesized resins.

The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation were determined by gamma- ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone (El Has- hash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization, dedolomitization, karstification and lateri- tization. The specific radioactivity of 238 U, 226 Ra, 232 Th and 40 K determined in different samples, indicate that 238 U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of 238 U reached up to 2129.36 ppm in argillaceous sedi- ments. The average concentrations of determined radio- nuclides ( 238 U, 226 Ra, 232 Th and 40 K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm, 808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%, respectively. The 238 U/ 226 Ra ratio in sandstone ranges between 0.89 and 1.25, while in do- lostones and argillaceous sediments are 0.27-2.63 and 0.27-1.83, respectively. These variations in the concen- trations of radioelements and their ratios are due to the action of the alteration processes affected these different sedimentary rocks in different times. Environmentally, the Raeq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible levels.

Uptake of uranyl ions on polyacrylamidoxime resins synthesized from polymerization of acrylonitrile, and divinylbenzene as crosslinking agent in the presence of different diluents, then conversion of polyacrylonitrile to polyacrylamidoxime by hydroxylamine in basic media were investigated. FTIR on base polymer, functional resins, resins loaded with uranyl ions and that after elution were investigated. The effect of pore solvents on the morphologies of the prepared resins were examined by scanning electron microscope. Loading of uranyl ions performed with respect effects of pH, time of loading, and ratio of crosslinker. Elution of adsorbed ions carried out with different eluent and elution efficiency were determined. Regeneration of resins performed after six cycles and regeneration efficiency were determined.

Radon exhalation rates from five studied laboratory waste samples resulted from five different sedimentary rock types named sandy dolostone, siltstone –two samples-, marly claystone and black shale were measured using ‘‘Sealed Can technique”. These rates were found to vary between 0.005 and 0.015 Bq m−2 h−1. A positive correlation was found between the radon exhalation rates and the radium activities. The emanation coefficients were calculated for these laboratory waste samples which varied between 0.0004 and 0.0007 according to the physical and chemical characterize of the wastes. These results are partially in accordance with autonite acid leached tailings on laboratory scale (USA). These results led us to pay attention about the effect and impact of these wastes on the environment.