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Purpose. To assess the impact of mining waste on the heavy metal content of water surfaces, plants, and topsoil near the tailings dam of a Zn-Pb mine using both biotests and analytical methods. Methodology. A battery of microbiotests on different animal and plant species was carried out, making it possible to evaluate the toxic effect of residues and surrounding soils on living organisms. Furthermore, the possible relationship between the observed toxicity and the results of the physicochemical analysis of the samples was studied. Findings. The tests showed that the topsoil in contact with the tailings dam is slightly toxic to the living organisms used while the mining tailings are toxic or even very toxic. The heavy metal content of the samples is particularly high for Fe, Zn, Pb and Cu. The correlation of physic-chemical parameters and the results of microbiotests using the principal components analysis (PCA) and the multiple correspondence factor analysis (MCFA) indicate that the toxicity of tailings and the surrounding topsoil can be associated with anthropogenic mining activity. Originality. The study aimed to assess the impact of mining waste on the heavy metal content using biotests and analytical methods. The evaluation considers the concentrations of the samples (highly concentrated samples and samples after dilution) and the different phases of exposure (solid, liquid) for a more detailed assessment of the potential toxicity of the samples. Practical value. It is important to conduct a comprehensive assessment of mining waste and the risks it may pose to humans and the environment in order to develop an adequate rehabilitation plan. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose. Choice of a method for treating the iron ore of the Khanguet mine depending on its characterization. Methodology. This work is focused on the study on physicochemical and mineralogical characterization of the poor iron ore of Khanguet mine, using multiple analysis techniques (X-ray diffraction, X-ray fluorescence, scanning electron microscope and optical microscope), to identify the chemical composition and mineral phases of the ore. The study also focused on the possibility of enrichment, using the electrostatic separation process. For this purpose, two main parameters are studied, such as, the voltage between the electrodes and the rotation speed of the roll. Findings. The results of the characterization show the possibility of using the process of electrostatic separation for the enrichment of the Khanguet ore, which allows increasing the content of Fe2O3 up to 58.46%. Originality. The originality of this work is the possibility to use the electrostatic treatment process for the poor iron ore of the Khanguet iron mine. Practical value. This study shows that the results obtained by the process of electrostatic treatment of ore are very significant; this technique makes it possible to obtain a concentrate with an iron content of 58.46% and to bring an added value to the company and the steelmaking industry, on the one hand, and, on the other hand, to eliminate reserves of these poor iron ores stored near the mining site, which is harmful for the environment. [ABSTRACT FROM AUTHOR]

In this investigation, Co–, Ni- and Cu-doped ZnO nanoparticles were prepared using precipitation methods. The characterization of the as-prepared nanomaterials was carried out using XRD, FT-IR, DRS, XPS and SEM. The XRD analysis showed that the insertion of foreign metal ions into the matrix of ZnO caused a slight shift of the positions of (100), (002) and (101) diffraction peaks of ZnO towards the lower 2θ, by comparison with pure ZnO. The DRS results showed that Co-doped ZnO nanoparticles absorb wavelengths higher than 400 nm. The estimated band gaps (eV) were 2.48, 3.17 and 3.14 for 10 %Co-ZnO, 10 %Ni-ZnO and 10 %Cu-ZnO respectively. The XPS results showed the existence of two valence states for Co and Ni (Co2+/Co3+ and Ni2+/Ni3+) while Cu exists in the form of Cu2+. The photocatalytic efficiency was evaluated under UV and visible irradiations in aqueous solution using methyl orange (MO) as an organic pollutant probe molecule. The results showed that, under visible light, the MO degradation increased significantly by doping ZnO (10 %Co-ZnO: 33.2 %; 10 %Ni-ZnO: 19.8 % and 10 %Cu-ZnO: 52.5 %) by comparison with undoped ZnO (9.3 %). The important increase in photocatalytic activity observed for the doped ZnO by comparison with pure ZnO, particularly for 10 %Cu-ZnO, has been linked to a synergistic effect of both the band gap narrowing and the increase in the lifetime of photogenerated charge carriers.

In this paper, it was aimed to select and propose a feasible as well as an applicable method, for the extraction of zinc that was present in the disposed GHAZOUAT leach residues having 17.82 wt. % Zn and 20.82 wt. % Fe. After the determination of the components of the residue, the acid leaching was performed to reclaim Zn sequentially. The acid leaching experiments were carried out for Zn extraction by controlling acid concentration, reaction duration and temperature. At the optimum conditions, 240 g/L H2SO4 at 90 °C for 210 min, 80% of initial iron content was removed, and the resultant overall zinc extraction was usually superior than 96%. [ABSTRACT FROM AUTHOR]

In this work we report on a study of the mechanism of O[sup -] electron stimulated desorption (ESD) from hydrogenated and hydrogen-free polycrystalline diamond films exposed to thermally activated oxygen for incident electron energies in the 4-22 eV range. Two types of experiments were carried out in order to assess the nature of the ESD processes: (i) total O[sup -] and H[sup -] yields as a function of incident electron energy and (ii) kinetic-energy distribution (KED) of O[sup -] desorbed from the hydrogen-free diamond surface. The discussed ESD mechanism is referred to the information obtained from x-ray photoelectron spectroscopy, near-edge x-ray absorption fine structure, and core level H[sup +] photodesorption measurements which reveal formation of C=O and C-O-C bonds on the hydrogen-free diamond surface, and C=O and C-O-H bonds on the hydrogenated one. Based on the maximum kinetic-energy value of O[sup -] and the ESD threshold measured for hydrogen-free surface, all low-energy (5-10 eV) O[sup -] ions are attributed to desorption by the dissociative electron attachment (DEA) to C-O-C, while DEA to C=O occurs at the incident electron energy higher than ∼10 eV. O[sup -] ESD from the hydrogenated diamond surface exposed to thermally activated oxygen is a more complicated process. Its threshold is substantially higher than for hydrogen-free diamond, and the line shape of the ESD yield curve is very similar to that of chemisorbed CO molecules. Several reaction pathways leading to production of O[sup -] by DEA are discussed for this sample. At incident electron energies higher than ∼15 eV, O[sup -] ESD proceeds also via dipolar dissociation processes for both hydrogenated and hydrogen-free diamond surfaces. [ABSTRACT FROM AUTHOR]

In this work, the decay of secondary-electron emission (SEE) intensity and charging of hydrogenated and hydrogen-free diamond film surfaces subjected to incident electron irradiation at energies between 5 and 20 eV are investigated. Electron emission curves as a function of incident electron energy were measured. For the hydrogenated films, it was found that the SEE intensity decays in intensity under continuous electron irradiation, albeit maintains a nearly constant onset. The decay in time of the SEE intensity was measured for various incident electron energies. From these measurements, the SEE intensity decay rate from the hydrogenated diamond surface was calculated as a function of incident electron energy and found to display a broad peak at ∼9 eV. The decay of the SEE intensity is explained as due to electron trapping in the near-surface region of the hydrogenated diamond films resulting in the formation of a depletion layer and upward surface band bending while overall charge neutrality is maintained. It is suggested that the mechanism of charge trapping is by resonant electron attachment of incident electrons into C-H (ads) bonds present within the near-surface region of the hydrogenated diamond films which displays a similar dependence on incident electron energy. Upward band bending results in a surface potential barrier to secondary electrons created within the solid. For the hydrogen-free diamond surface, decay in intensity and a positive shift in the onset of the SEE were observed for all incident electron energies and currents used. It was found that surface charging increases monotonically with incident electron energy. In this case, charging is associated with electron trapping into localized surface states of π[sup *] symmetry. These electronic states are associated with surface reconstruction resulting from hydrogen desorption. [ABSTRACT FROM AUTHOR]

Morocco, which is in a seismically active zone, is currently experiencing a significant development in terms of the realization of development and infrastructure projects. Therefore, reflection on soil liquefaction problems during project design is essential. The densification of soils by vibro compaction is a recent process of soil treatment, its effect is to improve the geo mechanical characteristics of the soil in this case the relative density and subsequently the reduction of the potential for liquefaction, it is a technique soil improvement in the mass, it is closely linked to the grain size of the soil to be treated, its percentage of fines less than 10% (going to 0.08 mm

This research work is focused in study of the dilation/retreat properties of ceramic membranes and its characterization. The clay used in this work is collected in the region of Midelt in Morocco. This raw material has been characterized by XRD, FTIR, TGA/DTA and X-ray fluorescence. These analyzes show that this clay consists essentially of Quartz and Kaolinite. Then, the clay pastes containing different proportions of the organic additive are aged and used to develop rods and bricks of known geometric dimensions. However, the pastilles were developed by dry process. After drying in the open air with a different percentage of the organic matter (0–15%), the parts are treated at different temperatures (700, 800, 900, 1000 and 1050 °C) according to a suitable heating program, taking into account the initial mineralogical composition and the TGA/DTA thermograms of the samples. The dilation/retreat properties of the processed samples are discussed according to the variation of predetermined parameters such as weight loss, length, height and diameter. The evolution of the porosity, the mechanical and chemical resistance of the samples is determined. It has been found that the organic additive increases the porosity of the parts prepared by its degradation by the heat treatment and the results obtained show that the prepared materials have a high mechanical strength and chemical resistance and they have improved porosity. Indeed, the clay studied will be used to develop tubular membranes intended for the tangential filtration of wastewater, which will be the subject of the second part of this study.

Removal of para-nitrophenol (p-NP) from an aqueous solution was studied under various batch adsorption experiments, using alumina (Al2O3) and its composite hexadecyltrimethylammonium bromide (HDTMA+-Br−) as adsorbents. These were later characterized, before and after adsorption of p-NP, by thermal analysis (DSC-TG), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV/Visible spectroscopies. The results show that HDTMA+/Al2O3 adsorbents have a greater affinity toward p-NP than Al2O3 alone. Linear and non-linear forms of kinetics and isotherms were used to analyze the experimental data obtained at different concentrations and temperatures. The results indicate that the pseudo-second order kinetic model provided the best fit to the experimental data for the adsorption of p-NP on both adsorbents, and that the intra-particle diffusion was not only the rate controlling step. Both the Langmuir and Redlich-Peterson (R-P) models were found to fit the sorption isotherm data well, but the Langmuir model was better. Physical adsorption of p-NP onto the adsorbents proved to be an endothermic and spontaneous process at high temperatures, which mainly involves a hydrogen bonding mechanism of interactions between p-NP and functional groups of adsorbents. The antibacterial activity of Al2O3, HDTMA+-Br− and HDTMA+/Al2O3 were evaluated against Listeria monocytogenes and Salmonella spp. strains using both disc diffusion and broth microdilution methods. The HDTMA+-Br− and HDTMA+/Al2O3 displayed a bacteriostatic effect against all tested strains of Listeria monocytogenes and Salmonella spp., while Al2O3 exhibited no bacterial effect against all bacterial strains tested.

A raw Moroccan clay locally named “Ghassoul” (Gh) was characterized using several techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Brunauer, Emmett and Teller method (BET), Scanning Electron Microscopy (SEM) and simultaneous Thermo-Gravimetric and Differential Thermal Analysis (TGA/DTA). These techniques indicate that the Gh consists essentially of steveniste, calcite, dolomite and quartz. The study of the interfacial electrochemical properties of Gh in different solutions of electrolyte salts (NaCl, CsCl, NaF, NaBr and LiCl) was carried out using the potentiometric and conductometric titrations It was shown that the Gh particles were stable in aqueous phase within the pH range (3–12) and the point of zero charge (PZC) was located at pH = 10.7. The adsorption sequence, carried out at various ionic strengths, showed that the adsorption mechanism onto the Gh particles is both electrostatic and specific at pH below the pHpzc, while at a pH range greater than the pHpzc the mechanism is electrostatic in nature. The total number of surface sites, determined using the graphical extrapolation method, was 11OH/nm2. Ionization constants (pKint+ and pKint−) in the presence of various electrolytes have also been determined and their values are 10.08 and 12.38, respectively.