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Assessment of Heavy Metals (As, Cd, Hg, Pb) in Sources of Water for Human Consumption in Sub-Saharan Africa: A Literature Review
Alassane Youssao Abdou Karim,
Emmanuel Azokpota,
Léonce Firmin Dovonon,
Abdoul Kader Alassane Moussa,
Alphonse Sako Avocefohoun,
Daouda Mama,
Dominique Codjo Koko Sohounhloue
Issue:
Volume 11, Issue 1, February 2023
Pages:
1-9
Received:
26 December 2022
Accepted:
14 January 2023
Published:
30 January 2023
Abstract: In the world and particularly in Africa, the supply of drinking water by rural communities is still a challenge to be met due to the unavailability of water in quality and quantity. Indeed, 76% of the population in sub-Saharan Africa does not have access to drinking water. This situation is more pronounced in rural and peri-urban communities than in urban areas. Some communities, particularly in rural areas, are therefore condemned to consume surface water, rainwater and well water of dubious quality due to the contamination of this water and especially the lack of a drinking water distribution network. Several research studies on metal contamination of surface water, groundwater and rainwater have reported high levels of metals. This review article focuses on the contamination of waters in sub-Saharan Africa by cadmium, lead, mercury and arsenic, because of their toxicity and the health and ecotoxicological consequences linked to their presence in water. These are heavy metals at the origin of several dangerous diseases such as lead poisoning, hydrarygysmus, Itai Itai disease, etc. This article reviews the problems of accessibility to drinking water in communities in terms of quantity and quality, the origins and levels of water contamination by metals as well as analytical methods for metals and the consequences related to the consumption of these waters.
Abstract: In the world and particularly in Africa, the supply of drinking water by rural communities is still a challenge to be met due to the unavailability of water in quality and quantity. Indeed, 76% of the population in sub-Saharan Africa does not have access to drinking water. This situation is more pronounced in rural and peri-urban communities than i...
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Study of the Chemical Reactivity of a Series of Dihydrothiophenone Derivatives by the Density Functional Theory (DFT) Method
Fandia Konate,
Kadjo François Kassi,
Georges Stephane Dembele*,
Chiepi Nadege Dominique Dou,
Bibata Konaté,
Doh Soro,
Guy-Richard Mamadou Kone,
Nahosse Ziao
Issue:
Volume 11, Issue 1, February 2023
Pages:
10-17
Received:
30 December 2022
Accepted:
20 January 2023
Published:
14 February 2023
DOI:
10.11648/j.sjc.20231101.12
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Abstract: This chemical reactivity theory study was conducted on ten (10) molecules of a series of dihydrothiophenone (DH) substituted by the quantum chemical method using density functional theory, at the B3LYP/6-31G (d, p) level. A set of global and local descriptors were used to assess the reactivity of the molecular systems. In addition, the most relevant quantum chemical descriptors for the action of the molecule as an inhibitor, such as the highest occupied molecular energy (EHOMO), the lowest vacant molecular orbital energy (ELUMO), the energy gap (ΔE), the dipole moment (μ), electronegativity (χ), overall hardness (η) and overall softness (Ѕ) on the heteroatoms were calculated. The analysis of the thermodynamic formation quantities confirmed the formation and existence of the studied series of molecules. The study of the boundary molecular orbitals provided a better overview of the molecular activities. The analysis of the global descriptors revealed that the DH1 molecule has the lowest value of energy gap. This lower gap allows it to be the most reactive (soft) and the least stable molecule. Also we note that it has the lowest hardness, but the highest softness. This indicates that it is the most electrophilic of all the compounds.
Abstract: This chemical reactivity theory study was conducted on ten (10) molecules of a series of dihydrothiophenone (DH) substituted by the quantum chemical method using density functional theory, at the B3LYP/6-31G (d, p) level. A set of global and local descriptors were used to assess the reactivity of the molecular systems. In addition, the most relevan...
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Synthesis, Spectroscopic Characterization, and X-ray Structure of the Co-crystal Copper(II) Complex of the Dissymmetrical 1-(2 hydroxy-3-methoxybenzylidene)-5-(pyridin-2 ylmethylene) Carbnohydrazide Ligand
Ndiouga Fall,
Bocar Traore,
Mbosse Ndiaye-Gueye,
Ousmane Diouf,
Ibrahima Elhadji Thiam,
Simon Coles,
James Orton,
Mohamed Gaye
Issue:
Volume 11, Issue 1, February 2023
Pages:
18-25
Received:
10 January 2023
Accepted:
30 January 2023
Published:
14 February 2023
Abstract: In the pentanuclear title complex, bis{μ2-1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide}-1κ4O,N,N’,N’’:2κ2O,N;2κ2O,N:3κ4O,N,N’,N’’-1,2,3-tricopper(II) bis{[1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide]-κ4O,N,N’,N’’-copper(II)} tetraperchlorate tetrahydrate (1), two monocationic mononuclear units and one dianionic trinuclear unit co-exist. The CuII centers in the mononuclear units as well as the two terminal CuII centers in the trinuclear unit are located in the N3O cavity of the ligand and are coordinated to a phenolate oxygen atom, to a pyridine nitrogen atom, to an imino nitrogen atom and to a hydrazinyl nitrogen atom. The third central Cu(II) atom in the trinuclear unit, which is hexacoordinated, is located in N2O4. The metal center is coordinated to two ligand molecule through one imino nitrogen atom one oxygen atom of a carbonyl moiety per ligand and two oxygen atom of water molecules. The tetracoordinated copper(II) ions are situated in distorted square planar environments, while the hexacoordinated copper(II) is located in octahedral geometry. In the mononuclear units, as well as in the trinuclear units, the methoxy oxygen atoms remain uncoordinated. Each atom of the uncoordinated perchlorate anions is disordered over two sets of sites in a 0.5 ratio. Four free water molecules are also present. In the crystal, the trinuclear cationic unit and the mononuclear cationic units are assembled into infinite layers. These layers are held together via electrostatic interactions, forming a three-dimensional structure.
Abstract: In the pentanuclear title complex, bis{μ2-1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide}-1κ4O,N,N’,N’’:2κ2O,N;2κ2O,N:3κ4O,N,N’,N’’-1,2,3-tricopper(II) bis{[1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide]-κ4O,N,N’,N’’-copper(II)} tetraperchlorate tetrahydrate (1), two monocationic mononuclear ...
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Comparison of the Chemical Composition of L. schlechteri with Other Selected Green Leafy Vegetables
Arnaud Wenceslas Geoffroy Tamba Sompila,
Nadia Pamela Gladys Pambou-Tobi,
Roniche Nguie,
Michel Elenga
Issue:
Volume 11, Issue 1, February 2023
Pages:
26-35
Received:
17 January 2023
Accepted:
10 February 2023
Published:
28 February 2023
Abstract: The present study, aimed at analyzing by comparison the nutritional, mineral and fatty acid composition of some available green leafy vegetables, will promote an increased use and consumption of these vegetables for their contribution as a source of nutrients. L. schlechteri was used as a reference vegetable to perform this comparison. Recommended AOAC methods were used for the determination of moisture, ash, lipids, carbohydrates, and proteins of L. schlechteri, while the gas chromatographic method was used to evaluate the fatty acid profile of the extracted oil. The results showed that the ash of its vegetables ranged from 1.71 to 30.62% (b.h). Moisture was higher in L. schlechteri (97.50% b.h) and lower in C. integrifolia. (61.22% b.h). Protein and carbohydrate contents varied widely from 3.5 to 30.62 g/100 g, and from 2.30 to 63.22 g/100 g respectively. Lipids were higher in L. schlechteri (7.85%) and lower in Hibiscus c. (0.20%), while the calorific value in all leafy vegetables was relatively low. L. schlechteri had the highest calcium (1160 mg/100 g) and iron (400 mg/100 g) contents, M. oleifera in Mg (1910 mg) and finally G. africanum in phosphorus (1340 mg/100 g). It should also be noted that the PMQ oils contain 5 main fatty acids: palmitic, C16:0 (15.7-63%); stearic, C18:0 (1-2.50%); oleic, C18:1 (2-5.1%); linoleic, C18:2 (4-28.68%) and linolenic (9-53%). The values of ω6/ω3 and PUFA/SFA ratios are within the recommended levels for edible oils.
Abstract: The present study, aimed at analyzing by comparison the nutritional, mineral and fatty acid composition of some available green leafy vegetables, will promote an increased use and consumption of these vegetables for their contribution as a source of nutrients. L. schlechteri was used as a reference vegetable to perform this comparison. Recommended ...
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Chemical Stability of Imidazole-Thiosemicarbazides in Solvents: NBO Studies and Theoretical Absorption Spectrum
Mamadou Guy-Richard Kone,
Adama Niare,
Bafétigué Ouattara,
Georges Stéphane Dembele,
Panaghiotis Karamanis,
Nahossé Ziao
Issue:
Volume 11, Issue 1, February 2023
Pages:
36-44
Received:
30 January 2023
Accepted:
20 February 2023
Published:
28 February 2023
Abstract: This study of chemical stability in solvents was performed on four (4) molecules of a series of halogen-substituted imidazole-thiosemicarbazides (IT) using the TD-DFT method at the B3LYP/6-31+G (d, p) level. The solubility of the imidazole-thiosemicarbazides in solvents across the dipole moment revealed that the ITs have the lowest values of the dipole moment in cyclohexane, indicating that the ITs are more soluble in cyclohexane. This claim was confirmed by the assessment of the energy gap in the different solvents. Analysis of the effect of temperature on the stability of imidazole-thiosemicarbazides showed that temperature has no effect on the stability of the ITs studied. This observation could allow to fight effectively against the different bacteria and to control their storage conditions and also to establish their expiry dates. The NBO analysis and the study of the absorption spectrum were also carried out in order to show the hyperconjugative interactions and the delocalization of atomic charges. In this case, the stabilizing interactions involve the free pairs of nitrogen atoms N16 and N19 and the antibinding single bond are σ*(C18-S21). Analysis of the theoretical absorption spectrum showed that the absorption band representing cyclohexane is more intense for all the compounds studied. This is because cyclohexane better promotes the stabilization of substituted imidazole-thiosemicarbazides. Moreover, the maximum band corresponds to the electronic transition between the HOMO and the LUMO is due to an electron displacement from the LP (N) orbitals towards the σ*(CS) orbitals.
Abstract: This study of chemical stability in solvents was performed on four (4) molecules of a series of halogen-substituted imidazole-thiosemicarbazides (IT) using the TD-DFT method at the B3LYP/6-31+G (d, p) level. The solubility of the imidazole-thiosemicarbazides in solvents across the dipole moment revealed that the ITs have the lowest values of the di...
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