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Electrochemical Analysis of Zirconiumin Aqueous and Organic Media

American Journal of Analytical Chemistry 2024年第2期15卷 99-118页

作者： Paul Mendy Démo Koita Theodore Tzedakis Cheikhou Kane codou gu.ye mar-diop Ecole Supérieure Polytechnique Université Cheikh Anta DIOP Dakar Sénégal Laboratoire de Génie Chimique Université de Toulouse III—Paul Sabatier Toulouse France

For the challenging nature of the zirconium environment analysis, this study consists to analyze the electrochemical behavior of Zirconium in both aqueous and organic media. To that end first the electrolytic media was selected on the basis of the Pourbaix potential-pH diagram, which provides informations on the predominance of Zr(IV) ion and Zr in aqueous media. In aqueous media, analyzes were first carried out in acidic media then in basic media. Studies have thus revealed that the acidic environment is not favourable for the electrochemical analysis of zirconium. Voltammograms obtained in an acidic environment show no zirconium detection signal;this is due to the strong presence of H+ ions in the solution. We have also observed in acidic media the phenomenon of passivation of the electrode surface. In aqueous alkaline media (pH = 13), we have drawn in reduction several Intensity-Potential curves by fixingsome technical parameterslike scanning speed, rotation speed of the electrode. The obtained voltammograms show cathodic waves, starting from -1.5 V/DHW and attributed to the reduction of Zr (IV) to Zr (0). The last phase of this study focused on the electrochemical analysis of zirconium in an organic media. In this media, several intensity-potential curves were plotted in reduction and in cyclic voltammetry with various parameters. Through several reduction analysis, the Zr (IV) was reduced to Zr (0) to the potential of -1.5 V/DHW. The electrochemical analysis of zirconium in organic media seems globally easier to achieve thanks to its large solvent window (i.e. dimethylformamide (DMF) solvent window > 6 V).

关键词： Zirconium Electrochemical Reduction Cyclic Voltammetry Voltammogram Dymethylformamide

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Removal of Methyl Violet in Aqueous Solution on Activated Carbon Based on Saba senegalensis Shell Residues

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Journal of Geoscience and Environment Protection 2023年第5期11卷 197-208页

作者： Mouhamed Ndoye Mamadou Faye Cheikhou Kane Adama diop mar codou gu.ye diop Water Energy Environment and Industrial Processes Laboratory Ecole Superieure Polytechnique (ESP) Dakar Senegal Cheikh Anta diop University Dakar Senegal

Adsorption on activated carbon is one of the most widely used methods for the removal of dyes. The objective of this study is to valorize the shells of Saba senegalensis from local product in Senegal in the form of activated carbon and to test its effectiveness for the removal of methyl violet. The study was carried out in batch mode for a maximum duration of one hour with 100 mL of solution treated at 600 rpm. The results reveal that the granulometry 500 μm gives the best yield with an adsorption rate of 95%, a mass of adsorbent of 0.2 g gives an adsorption capacity of 20 mg/g, the contact time of one hour with a capacity of 5 mg/g. The study also showed that the adsorption process of methyl violet is described by the pseudo-second order kinetic model with correlation coefficient of 0.99. Two adsorption isotherms were studied, and the results revealed that the Freundlich model better describes the adsorption of methyl violet on Saba senegalensis shell residue-based activated carbon (SSSRAC). The results indicate that SSSRAC could be used as a low-cost alternative for the removal of textile dyes such as methyl violet.

关键词： Methyl Violet Adsorption Activated Carbon Saba senegalensis Shell

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Process for the Biological Removal of Fe (II) from Reconstituted Waters on a Support of Filter Material with Coated Jujube Seeds

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Journal of Geoscience and Environment Protection 2022年第12期10卷 65-76页

作者： Mamadou Faye Falilou Mbacké Sambe Alpha Ousmane Toure Mouhamed Ndoye codou gu.ye mar diop Water Energy Environment and Industrial Processes Laboratory Ecole Supérieure Polytechnique (ESP) Dakar Senegal Cheikh Anta diop University Dakar Senegal

Three beakers for removing Fe (II) in reconstituted water (doped with FeSO4) were built and tested. Given the set operating conditions ([O2] > 4 mg·L-1, Patm = 1.013 bar, T = 25°C ± 1°C and [Fe2+]0 = 0.5 to 2 mg·L-1), removal of iron was caused by biological and possibly physical and chemical oxidation because there is a quantity of free oxygen in the medium. The extent of each type of oxidation has not been evaluated as it specifically studies the biological degradation of iron in these beaker tests by setting the operating conditions (pH > 6.5, dissolved oxygen from 0 to 8 mg·L-1, Redox Potential from 100 to 400 mV). The experimental studies focused particularly on the measurements of maximum wavelength, conversion efficiencies from Fe (II) to Fe (III), the effect of the Fe (II) concentration, the influence of pH, the action of the temperature of the prepared solutions and the effect of O2 concentration under specified operating conditions. It noticed precipitated amounts of iron deposited at the bottom of the beakers. Thus, the low concentrations of Fe (II) detected in the influent after the biological oxidation operation could be attributed to microorganisms that consume iron as a substrate.

关键词： Biofilm Batch Test Biological Oxidation Iron Removal Beaker Doped Water

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Iron in Water: Study of Iron Removal Kinetics in Chemically Reconstituted Waters: Application to Groundwater of South Pout (PS2 Site)

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Open Journal of Metal 2021年第1期11卷 1-10页

作者： Faye Mamadou Sambe Falilou Mbacké diop El Hadji Moussa Toure Alpha Ousmane Mbaye Fall Aminata diop mar codou gu.ye Laboratory of Electrochemistry and Membrane Process Ecole Supérieure Polytechnique Cheikh Anta Diop University Dakar Senegal Quality Control Analysis Laboratory of the Senegalese Water Company (SWC) Dakar Senegal

The goal of this topic is a synthesis of the main characteristics of iron in groundwater and the oxidation process used to remove it. Indeed, the kinetics of chemical oxidation of iron (II) was examined with reconstituted water (distilled water + iron sulphate) and proceeded to the application in the groundwater samples taken from South Pout (Senegal) precisely in the drilling PS2. The sources of iron are natural or anthropogenic. In Senegalese waters, its content is variable and sometimes exceeds the standards of potability. Despite the diversification of iron removal process, chemical oxidation is the most used solution in drinking water treatment plants in Senegalese rural areas. Applied oxidation processes such as aeration and chlorination, however, are insufficient to produce drinking water with an iron concentration in accordance with standards of potability.

关键词： Iron Kinetics Chemical Oxidation Groundwater Drilling

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Isolation of Iron Bacteria from Washing Sludge Filters Kolda (Senegal) Water Treatment Station and Study of the Kinetics of Biological Degradation of the Iron (II)

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Open Journal of Metal 2019年第3期9卷 19-32页

作者： Mamadou Faye Falilou Mbacké Sambe Modou Dieng Alpha Ousmane Touré Matar Faye codou gu.ye mar diop Laboratory of Electrochemistry and Membrane Processes (LEMP) Ecole Supérieure Polytechnique (ESP) Dakar-Fann Senegal Cheikh Anta diop University of Dakar (UCAD) Dakar-Fann Senegal Microbiology Laboratory of the Department of Chemical Engineering and Applied Biology (ESP) Dakar-Fann Senegal

In the present work, the treatment of synthetic waters doped with iron (II) has been studied. The treatment mechanism used in this study is the biological oxidation which consists, in test tubes, of bringing bacteria isolated on Petri dishes into contact with water containing divalent iron (II). These de-ironing bacteria (non-specific bacteria) are used to carry out laboratory biological oxidation experiments on iron (II) under different pH conditions (pH = 3.4 - 3.6, pH = 7.3 - 7.5 and pH = 9.8 - 10) and variable concentration of iron (II). Biological treatment trials included different concentrations of iron during time intervals of a day. Examination of the elimination kinetics of Iron (II) indicates a removal rate of 59.453% for an initial iron concentration in the synthetic solution of 1 mg·L−1 at basic pH (pH = 9.8 - 10). Therefore, the degradation of divalent iron by this method seems to be quite effective, but it should be noted that biological nitrification is impaired by the presence of high iron concentrations above 5 mg·L−1.

关键词： Biodegradation Bacteria Washing Mud Iron Kinetics Efficiency

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Determination of Lead in Water by Linear Sweep Anodic Stripping Voltammetry (LSASV) at Unmodified Carbon Paste Electrode: Optimization of Operating Parameters

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American Journal of Analytical Chemistry 2018年第3期9卷 171-186页

作者： Ndoye Mouhamed Kane Cheikhou Gadji Elhadji Momar Rokhy Diédhiou Moussa Bagha mar-diop codou gu.ye Theo Tzedakis Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Laboratoire de Génie Chimique UMR CNRS 5503 Université de Toulouse III-Paul Sabatier Toulouse France

This study presents the elaboration of a simple and cheap electrode made by carbon paste introduced into a cavity of electrode body, and used for the lead traces determination in tap water. A potentiostatic pre-electrolysis at constant voltage enables the reduction of the lead (Pb2+) and the accumulation of the metallic lead at and into the carbon paste;the reoxidation of the Pb (Linear sweep voltammetry) leads to the anodic striping peak. The effect of the main operating parameters on the shape of the peak and the magnitude of the current was examined and their optimal values were determined. Then calibration was achieved and the method was successfully applied (using all the optimized parameters) to the determination of lead in water, with a detection limit of 0.138 μg·L-1. Compared to other methods (ICP-AES for example), the proposed method offers a satisfactory detection limit of the Pb2+ (0.138 μg·L-1) because of the important specific area of the carbon paste electrode, for a significantly lower cost. Besides, there is no observed loss in the electrode answer in terms of peak current, which means that there is no any irreversible steps nor deactivation of the electrode, even after ten successive measurements;only reduction of the lead followed by the deposit oxidation was observed at the electrode.

关键词： Carbon Paste Electrode Lead Linear Sweep Anodic Stripping Voltammetry Water

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Antioxidant Activity of Hydro-Acetonic, Hydro-Methanolic and Aqueous Leaf and Bark Extracts of Sclerocaria birrea(A. Rich.) Hochst

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Food and Nutrition Sciences 2021年第5期12卷 429-438页

作者： Lahat Niang Seid Ali Mahamat Nicolas Cyrille Ayessou Mady Cisse codou mar diop Laboratory of Electrochemistry and Membrane Processes (LEPM) ESP-UCAD Dakar Sénégal Center for Studies on Food Safety and Functional Molecules (CESAM-RESCIF) ESP-UCAD Dakar Sénégal Adam Barka University Abeche Tchad

Bioactive compounds in plants are associated with the reduction of chronic diseases. The free radical scavenging activity of different extracts of a medicinal plant, Sclerocarya birrea, has been investigated using the DPPH test, ABTS test and FRAP. Three extracts were prepared from the leaves and bark: hydro-methanolic, hydro-acetonic and aqueous. Phytochemical screening was carried out the standard methods followed by the determination of the polyphenol by Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 and statistical significance was set at p 0.05. Evolution of percent inhibition (PI) as well as the IC50 of the extracts was obtained using the Origin Pro 8.5 software and Microsoft Excel. The results show that the bark extracts

关键词： Sclerocarya birrea Antioxidant Activity DPPH ABTS Total Phenolic

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Nutritional Potential of Two Leafy Vegetables Leptadenia hastataDecne and Senna obtusifoliaLink Consumed in Senegal

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Food and Nutrition Sciences 2018年第2期9卷 77-85页

作者： Nicolas Cyrille Ayessou Mady Cissé Mathieu gu.ye Cheikh Ndiaye codou mar diop 1Laboratoire d’Electrochimie et des Procédés Membranaires Centre d’Etudes sur la Sécurité Alimentaire et les Molécules Fonctionnelles-Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Laboratoire d’Electrochimie et des Procédés Membranaires Centre d’Etudes sur la Sécurité Alimentaire et les Molécules Fonctionnelles-Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Institut Fondamental d’Afrique Noire Cheikh Anta diop Département de Botanique et Géologie Université Cheikh Anta Diop Dakar Senegal Laboratoire des Biotoxines et Contrô le des Aliments Institut de Technologie Alimentaire (ITA) Route des Pères Maristes Dakar Senegal

This study focused on two woody leafy vegetables Leptadenia hastata Decne and Senna obtusifolia Link, commonly consumed in Senegal. Leaves were col-lected from three regions. Then, proximate analyses and micronutrients were carried out to evaluate their nutritional values. Results revealed that protein level of S. obtusifolia (SO) is richer (21.75%) than Leptadenia hastata (LH) (18.16%). The cellulose and carbohydrate contents of the two vegetable’s leaves are in the same order except those of LH from Widou which are less rich in cellulose (8.31%) and richest in carbohydrate (6.35%). These leaves are also good sources of various mineral elements and especially iron. Leaves of LH appear to be richer in iron and magnesium, while SO appears to be richer in calcium. Vitamin C intakes of SO leaves are better than those of LH and respectively range from 142 to 196.5 and 22.5 to 159.5 mg/100 g. According to the use of this leafy vegetable by the populations, a domestication opportunity is thus justified to ensure availability and accessibility of these significant sources of micronutrients.

关键词： Leptadenia hastata Senna obtusifolia Woody Leafy Vegetables Nutritional Values Domestication

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Phytochemical Screening, Total Phenolic and Antioxidant Activity of Numerous Extracts from Leaves and Bark of Bauhinia rufescensLam

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Food and Nutrition Sciences 2021年第6期12卷 544-556页

作者： Seid Ali Mahamat Niang Lahat Ayessou Nicolas Cyrille Cisse Mady diop codou mar Adam Barka University Abeche Tchad Water Energy Environment and Industrial Processes Laboratory (LE3PI) ESP-UCAD Dakar Sénégal Center for Studies on Food Safety and Functional Molecules (CESAM-RESCIF) ESP-UCAD Dakar Sénégal

Researches for natural antioxidants that play an important role in the prevention of diseases linked to free radicals have increased in recent years. In this study, antioxidant activity of Bauhinia rufescens Lam which is a medicinal plant was investigated. The methanol extract, acetone extract and water extract of leaf and trunk bark had antioxidant activity. Three methods were used: 2,2-diphenyl-1picryl-hydrazyl (DPPH), 2,2’-Azino-bis-(3-ethylbenzoth iazoline-6-sulfonic acid) (ABTS) and ferric ion reducing power (FRAP) by spectrophotometry. Phytochemical screening was carried out followed by the quantification of the total phenolic by the Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 software revealed significant differences (p 0.05). Percentage inhibition (PI) and IC50 of the extracts were obtained using the OriginPro 8.5 software. These tests show that the bark is as rich in total phenolic as the leaves. The DPPH test shows that at 2.5 mg/ml, the bark and

关键词： Bauhinia rufescens Lam Total Phenolic Antioxidant Activity

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Monitoring of Anthocyanins and Colour in Electrochemically Processed Hibiscus sabdariffaJuice

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Food and Nutrition Sciences 2021年第11期12卷 1073-1087页

作者： Khady Ndiaye Cheikhou Kane Omar Ben Khatab Cisse Nicolas Ayessou codou mar diop Laboratoire d’électrochimie et des Procédés Membranaires ESP/UCAD Dakar Sénégal Laboratoire de Formation Continue en Industrie Agroalimentaire ESP/UCAD Dakar Sénégal

The vital role of anthocyanins in Hibiscus sabdariffa L. is now known to most consumers. The richness of anthocyanins in antioxidants, vitamin C, minerals, etc., provides Hibiscus juice with proven nutritional qualities. The health requirements of recent years have made food products with added preservatives or processed at high temperatures less popular, thus explaining the new orientations towards innovative and interdisciplinary technologies. Anthocyanins from Hibiscus sabdariffa L. are, however, sensitive to degradation factors such as temperature, light, enzymes and also oxygen. The instability of anthocyanins has long been a subject of research using classic techniques such as heat treatment, the results of which are often limited by the rapid degradation and above all the destruction of the nutritional and organoleptic qualities of the product. Oxygen dissolved in juices is so far treated by bubbling with an inert gas or by adding other molecules such as preservatives which can cause a lot of health damage. The electrochemical approach is a new stabilisation technique that reduces the dissolved oxygen in the juice, cold and without the addition of other molecules. The electrolysis of Hibiscus juice was carried out by noble electrodes (Platinum and Stainless Steel) with a well-characterised Time/Potential or Time/Intensity couple. The electroreduced samples and the control were then stored at 4°C, 25°C and 37°C for more than 6 months. Monitoring of anthocyanins in the first month, of the samples and the control, showed a significant difference of 10% between the electroreduced extract and the untreated control at 37°C, which had previously been problematic for the heat treatment and even for the other membrane techniques. Oxygen reduction on the platinum electrode/ECS allowed the retention of more than 10% of anthocyanins after 4 weeks of storage at 25°C and 37°C. At 4°C, a sign

关键词： Monitoring Anthocyanin Colour Oxygen Stabilisation Electrochemical Nafion Membrane Ratio

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