New Ethylenediamine Crosslinked 2D-Cellulose Adsorbent for Nanoencapsulation Removal of Pb (II) and Cu (II) Heavy Metal Ions: Synthesis, Characterization Application, and RSM-Modeling

The main objective of the present work is to elaborate on a new eco-friendly and efficient adsorbent designated for aquatic micropollutants removal. However, the synthesis of the Ethylenediamine Crosslinked 2D-Cellulose green adsorbent was carried out successfully, by partial grafting of benzyl entities onto hydroxyl groups of HEC, and crosslinking with ethylenediamine ED. Further, the new ethylenediamine crosslinked 2D-Cellulose was used as a biosorbent for nanoencapsulation removal of copper and lead heavy metal ions from aqueous solutions. The proposal chemical structures of unmodified and modified materials were confirmed using FTIR, XRD, TGA, and SEM–EDX analysis. Furthermore, many parameters of the optimization for Pb (II) and Cu (II) in terms of removal efficiency including pH, adsorbent amount, and contact time were optimized by response surface methodology with a Box–Behnken design. Based on the desirability optimization with three factors, the maximal removal was 99.52% and 97.5% for Pb(II) and Cu(II), respectively and was obtained at pH = 5.94, 22.2 mg as the optimal adsorbent amount, and 21.53 min as contact time

Protección frente a la corrosión de espumas de magnesio con aplicaciones biomédicas

[ES] Las espumas de magnesio presentan unas características que las hacen atractivas para su aplicación en la regeneración de tejido vivo. Sin embargo, se corroen fácilmente en el medio fisiológico, por ello, se busca la modificación superficial de estas espumas que les permita mantener su atractivo bioquímico o incluso mejorarlo y también obtener una mayor resistencia frente a la corrosión. En este trabajo se ha optado por el oxido de grafeno reducido (rGO), ya que este presenta unas buenas propiedades físicas y químicas, entre ellas, una buena resistencia frente a la corrosión, electroactividad, biocompatibilidad y mejora del crecimiento de tejidos, lo que lo hace ideal para la aplicación en la implantología biomédica.[EN] Magnesium foams have characteristics that make them attractive for their application in living tissue regeneration. However, they are easily corroded in the physiological environment, therefore, it is sought the superficial modification of these foams that allow them to maintain their attractive biochemical or even improve it and also to obtain a greater resistence against the corrosion. This work has opted for reduced graphene oxide (rGO), because of his good physical and chemical properties, among them, a good resistance against corrosion, electroactivity, biocompatibility and improvement of tissue growth. Ideal characteristic for its application in biomedical implantology.Ouardi, YE. (2018). Protección frente a la corrosión de espumas de magnesio con aplicaciones biomédicas. http://hdl.handle.net/10251/110294TFG

Bentonite et diatomite modifiées versus polymères à empreintes ioniques : vers de nouveaux matériaux pour l'extraction du nickel et de l'argent d'effluents contaminés

The brassware manufacturing of Fez city produces effluents that are very contaminated by metals such as nickel, silver, lead, copper and zinc. These effluents are directly discharged into the environment with a negative impact on the ecosystems and nearby wastewater treatment plant. Therefore, there is an urgent need for decontaminating these effluents before their treatment. In this context, the objectives of this work were the valorisation of natural mineral substances, bentonite and diatomite, widespread minerals in Moroccan soil although little exploited, for their use as adsorbent phases for nickel and silver extraction. A considerable part of this work has been directed toward modifying the physicochemical properties of these natural materials to maximize their adsorption capacity. In a first step, the modification of the diatomite was carried out by heating treatment at different temperatures (550 to 950 °C). The diatomite calcined at 550 °C showed the best adsorbing capacity towards nickel and silver. The second step was dedicated to the modification of the bentonite by heating treatment (550 °C and 750 °C) and chemical activation by sodium carbonate and by a combined chemical and thermal activation at 450 °C. Bentonites modified by chemical activation with sodium carbonate and by combined chemical and thermal activations at 450 ° C showed the best results. In addition, Ion Imprinted Polymers (IIPs) have been considered as alternative materials to replace these natural materials to improve the selectivity. The last part of this study consisted in comparing the performance of these materials, in order to select the best material for a future application in the remediation of contaminated effluents before their depollution by the treatment plant of Fez city. The nickel and silver concentrations become negligible in the natural samples after adsorption by the studied materials, which perfectly meets the Environmental Quality Standards. These results successfully validated the use of natural and synthetic materials for the extraction of nickel and silver from contaminated effluents.Les unités de dinanderies de la ville de Fès produisent des effluents très fortement contaminés par des éléments métalliques tels que le nickel, l’argent, le plomb, le cuivre ou encore le zinc. Ces effluents, déversés directement dans le réseau collectif, ont un impact négatif sur la station d’épuration proche. Il s’avère ainsi nécessaire de décontaminer ces effluents en amont de leur traitement. Dans ce contexte, les objectifs de ce travail étaient la valorisation de substances minérales naturelles, bentonite et diatomite, minerais abondants dans le sol national et peu exploités au Maroc, pour leur utilisation en tant que phase d’adsorption du nickel et de l’argent. L’objectif de ce travail a été de modifier les propriétés physico-chimiques de ces matériaux naturels pour maximiser leur capacité d'adsorption. Dans une première étape, la modification de la diatomite a été réalisée par traitement thermique à différentes températures (de 550 à 950 °C). La diatomite calcinée à 550 °C présente le meilleur pouvoir adsorbant vis-à-vis du nickel et de l’argent. La deuxième étape a été consacrée à la modification de la bentonite par traitement thermique (550 °C et 750 °C), par activation chimique par le carbonate de sodium et par activations combinées chimique et thermique à 450 °C. Les bentonites modifiées par activation chimique par le carbonate de sodium et par activations combinées chimique et thermique à 450 °C présentent les meilleurs résultats. En outre, des polymères à empreintes ioniques (IIPs) du nickel ont été considérés comme des matériaux alternatifs pour remplacer les matériaux naturels afin d'améliorer la sélectivité. La dernière partie a consisté à comparer les performances de ces matériaux, afin de sélectionner le meilleur matériau pour une future application dans la dépollution des effluents contaminés avant leur traitement par la station d'épuration de la ville de Fès. Les concentrations en nickel et argent résiduelles deviennent négligeables dans les échantillons naturels après l'adsorption par les matériaux étudiés dans ce travail, ce qui répond parfaitement aux Normes de Qualité Environnementale. Ces résultats ont permis de valider avec succès l’utilisation des matériaux naturels et de synthèse pour l’extraction du nickel et de l’argent issus d’effluents contaminés

Bentonite and diatomite modified versus Ion imprinted polymers : towards new materials for the extraction of nickel and silver from contaminated effluents

Les unités de dinanderies de la ville de Fès produisent des effluents très fortement contaminés par des éléments métalliques tels que le nickel, l’argent, le plomb, le cuivre ou encore le zinc. Ces effluents, déversés directement dans le réseau collectif, ont un impact négatif sur la station d’épuration proche. Il s’avère ainsi nécessaire de décontaminer ces effluents en amont de leur traitement. Dans ce contexte, les objectifs de ce travail étaient la valorisation de substances minérales naturelles, bentonite et diatomite, minerais abondants dans le sol national et peu exploités au Maroc, pour leur utilisation en tant que phase d’adsorption du nickel et de l’argent. L’objectif de ce travail a été de modifier les propriétés physico-chimiques de ces matériaux naturels pour maximiser leur capacité d'adsorption. Dans une première étape, la modification de la diatomite a été réalisée par traitement thermique à différentes températures (de 550 à 950 °C). La diatomite calcinée à 550 °C présente le meilleur pouvoir adsorbant vis-à-vis du nickel et de l’argent. La deuxième étape a été consacrée à la modification de la bentonite par traitement thermique (550 °C et 750 °C), par activation chimique par le carbonate de sodium et par activations combinées chimique et thermique à 450 °C. Les bentonites modifiées par activation chimique par le carbonate de sodium et par activations combinées chimique et thermique à 450 °C présentent les meilleurs résultats. En outre, des polymères à empreintes ioniques (IIPs) du nickel ont été considérés comme des matériaux alternatifs pour remplacer les matériaux naturels afin d'améliorer la sélectivité. La dernière partie a consisté à comparer les performances de ces matériaux, afin de sélectionner le meilleur matériau pour une future application dans la dépollution des effluents contaminés avant leur traitement par la station d'épuration de la ville de Fès. Les concentrations en nickel et argent résiduelles deviennent négligeables dans les échantillons naturels après l'adsorption par les matériaux étudiés dans ce travail, ce qui répond parfaitement aux Normes de Qualité Environnementale. Ces résultats ont permis de valider avec succès l’utilisation des matériaux naturels et de synthèse pour l’extraction du nickel et de l’argent issus d’effluents contaminés.The brassware manufacturing of Fez city produces effluents that are very contaminated by metals such as nickel, silver, lead, copper and zinc. These effluents are directly discharged into the environment with a negative impact on the ecosystems and nearby wastewater treatment plant. Therefore, there is an urgent need for decontaminating these effluents before their treatment. In this context, the objectives of this work were the valorisation of natural mineral substances, bentonite and diatomite, widespread minerals in Moroccan soil although little exploited, for their use as adsorbent phases for nickel and silver extraction. A considerable part of this work has been directed toward modifying the physicochemical properties of these natural materials to maximize their adsorption capacity. In a first step, the modification of the diatomite was carried out by heating treatment at different temperatures (550 to 950 °C). The diatomite calcined at 550 °C showed the best adsorbing capacity towards nickel and silver. The second step was dedicated to the modification of the bentonite by heating treatment (550 °C and 750 °C) and chemical activation by sodium carbonate and by a combined chemical and thermal activation at 450 °C. Bentonites modified by chemical activation with sodium carbonate and by combined chemical and thermal activations at 450 ° C showed the best results. In addition, Ion Imprinted Polymers (IIPs) have been considered as alternative materials to replace these natural materials to improve the selectivity. The last part of this study consisted in comparing the performance of these materials, in order to select the best material for a future application in the remediation of contaminated effluents before their depollution by the treatment plant of Fez city. The nickel and silver concentrations become negligible in the natural samples after adsorption by the studied materials, which perfectly meets the Environmental Quality Standards. These results successfully validated the use of natural and synthetic materials for the extraction of nickel and silver from contaminated effluents

Conception and Experimental Validation of a Standalone Photovoltaic System Using the SUPC5 Multilevel Inverter

In this work, an advanced pulse width modulation (PWM) technique was developed to provide the auto-balancing of the capacitors voltages of the five-level split-packed U-Cells (SPUC5) single-phase inverter, and then, the latter was applied to a photovoltaic (PV) system in standalone mode to evaluate its performance in this kind of application. The SPUC5 inverter makes use of only five switches (four active bidirectional switches and one four quadrant switch), one DC source and two capacitors to generate five levels of output voltage and a current with a quasi-sinusoidal waveform which reduces the total harmonic distortion (THD) without the need to add filters or sensors, and also reduces its cost compared to the other multilevel inverters. In the proposed system; the incremental conductance (INC) algorithm is combined with a DC/DC boost converter to reach the maximum power (MP) of the PV array by tracking the MP point (MPP). The offered concept has been constructed and then simulated in the MATLAB/Simulink environment to evaluate its efficiency. According to the results, the self-balancing of the capacitors voltages has been achieved. A comparative study was performed with the traditional PWM technique. The proposed PV system has been validated by experimental results

Novel Three-Phase Nine-Level Inverter and Its Control Strategies

In this paper, the authors propose a new three-phase, nine-level inverter with self-balancing of capacitors voltages. The proposed inverter is the result of a serial connection of the SPUC topology and the NPC converter. A single DC source is used, and each phase is made up of nine power switches and three capacitors. Two control techniques are proposed to maintain capacitors voltages at desired values, the first of which is a PWM technique ensures the self-balancing of capacitors voltages in open loop without using any filters or PI regulators, and the second is based on the hysteresis control which offers a nearly sinusoidal waveform of the load current without using any voltage sensors. The authors make use of the Matlab Simulink environment to perform the simulation of the proposed concept. The dynamics of the latter was verified against load change

Conception and Experimental Validation of a Standalone Photovoltaic System Using the SUPC5 Multilevel Inverter

In this work, an advanced pulse width modulation (PWM) technique was developed to provide the auto-balancing of the capacitors voltages of the five-level split-packed U-Cells (SPUC5) single-phase inverter, and then, the latter was applied to a photovoltaic (PV) system in standalone mode to evaluate its performance in this kind of application. The SPUC5 inverter makes use of only five switches (four active bidirectional switches and one four quadrant switch), one DC source and two capacitors to generate five levels of output voltage and a current with a quasi-sinusoidal waveform which reduces the total harmonic distortion (THD) without the need to add filters or sensors, and also reduces its cost compared to the other multilevel inverters. In the proposed system; the incremental conductance (INC) algorithm is combined with a DC/DC boost converter to reach the maximum power (MP) of the PV array by tracking the MP point (MPP). The offered concept has been constructed and then simulated in the MATLAB/Simulink environment to evaluate its efficiency. According to the results, the self-balancing of the capacitors voltages has been achieved. A comparative study was performed with the traditional PWM technique. The proposed PV system has been validated by experimental results

A gamma radiation exposure risk assessment using Monte Carlo simulation and an adult anthropomorphic phantom

The human body is vulnerable to exposure to ionizing radiation permanently. These radiations can be of natural origin such as soil and space, or of artificial and medical origins etc. Despite the great benefits that come from the applications of ionizing radiation in human life can turn at any time into threats to the life of the population once there is serious exposure to ionizing radiation. The aim of this work is to assess the risks of exposure by gamma radiation using the Monte Carlo simulation and an anthropomorphic phantom. This study is carried out on gamma rays received from the cobalt-60 irradiator of the National Institute of Agronomic Research (NIAR) Tangier / Morocco. With the code Geant4 we calculate the absorbed dose by the whole phantom body placed in front of the gamma irradiator inside the NIAR ionization cell. Dose calculations are made as a function of three parameters: phantom-irradiator distance, exposure time and as a function of gamma irradiator activity. The results clearly show that the dose absorbed and thus the danger of irradiation decreases by increasing the phantom-source distance, and by reducing the exposure time and the activity of the cobalt-60 source

Use of gamma irradiation for decorative coloring of glass in the Moroccan NIAR facility

The applications that cover the use of ionizing radiation are numerous, very diverse and belong to several fields of activity such as, the medical and agricultural fields etc. The aim of this work is to highlight an application of decorative glass coloring by gamma radiation. Crystal white glass cups are placed on small rotating tables and subjected to exposure to gamma radiation from the cobalt-60 gamma irradiator of the National Institute of Agronomic Research (INRA-Morocco / Tangier) for doses between 0 and 1.5 KGy. The results obtained show the variation in the color of glass between light brown to dark brown depending on the absorbed dose

Radiation protection study for a reloading operation of cobalt 60 sources in the Moroccan ionisation station using the GEANT4 Monte-Carlo simulation code

The operation of reloading the irradiators is considered among the tasks requiring high radiation protection monitoring, to protect the intervening manipulators, the public and the environment. Morocco is among the countries that have a cobalt irradiator, installed at the National Institute of Agricultural Research (NIAR) of Tangier, to carry out research in the field of agronomy. In the beginning, the irradiator used low doses of activity for the study of products only, for treatment of high doses. The NIAR carried out a reload to increase the activity. To perform this, a temporary pool was installed inside the irradiation room to handle the sources safely. A radiation protection study is necessary to ensure the safe operation. This operation requires a height level of exposure. To ovoid the exposer risk, it is proposed to use the Monte Carlo method thanks to its reliability in the dosimetric calculation. This article presents a radiation protection study of the Moroccan irradiator reloading operation using the GEANT4 Monte-Carlo Simulation Code