Kinetic and Thermodynamic Study of the Elimination of Remazol Black on Activated Carbon Based on Ricinodendron heudelotii Shells

Activated carbon made from the shells of Ricinodendron heudelotii was used to remove the remazol black dye in aqueous solution. The results of the characterization of this carbon revealed that it is microporous, with a basic global surface (0.337 mmol/L) and a specific surface of 612 m2/g. The prepared carbon therefore has excellent adsorbent properties. Kinetic and thermodynamic studies were carried out to describe the adsorption mechanism of remazol black on this carbon. It appears from this study that the pseudo-second-order kinetic model is the best suited to describe this adsorption phenomenon with an equilibrium time of 200 min. The adsorption equilibrium study revealed that Langmuir and Freundlich models can help to describe the adsorption process. We note that the optimum pH and optimum mass for the removal of 20 mg/L of remazol black are 3 and 0.25 g, respectively. This carbon made it possible to eliminate more than 98% of the remazol dye in aqueous solution. The thermodynamic study revealed that the adsorption is of the physisorption type, spontaneous and endothermic.

Comparison of Molecular Properties (Stabilities, Reactivity and Interaction) of Manzamenones and Two Antimalarial Drugs (Quinine and Artemisinin) Using Mixed Method Calculations (ONIOM) and DFT (B3LYP)

Malaria is a real public health problem. It’s one of the pathologies that mobilize the scientific community. Resistance to existing treatments is the basis for the search for new treatments. Some molecules such as Manzamenones have shown important antimalarial properties. These molecules belong to the family of atypical fatty acid derivatives. This work presents the relative stabilities, some reactivity properties and the privileged sites of interaction by hydrogen bond of fourteen Manzamenones and two antimalarial drugs: quinine and Artemisinin. These analyses were performed using quantum chemical calculations. We employed the two-layer ONIOM calculation method;namely ONIOM (B3LYP/6-311++G (d, p): AM1) for the fourteen Manzamenones. The geometries of the two antimalarials are calculated at B3LYP/6-311++G (d, p). The electrostatic potential (ESP) calculation of all molecules is done at the B3LYP/6-31++G (d, p) level. The formation processes of the molecules are discussed from the thermodynamic quantities we have calculated. The relative stabilities, the energies of the frontier orbitals, the energy gaps, the dipole moment, etc., are evaluated and discussed. The electrostatic potential at the molecular surface has been used to identify the sites favorable to the formation of hydrogen bonds.

Production and Characterization of Green Biosorbent Based on Modified Corn Cob Decorated Magnetite Nanoparticles

In most developing countries, particularly in the countries of sub-Saharan Africa, corn cobs are considered as waste polluting the environment during the harvest period of this cereal. In order to valorize this agricultural waste, high-performance, inexpensive and low-energy consumption magnetic bioadsorbents were prepared from corn cobs. The chemically activated raw corn cob was magnetized by coating the surface with magnetite nanoparticles. The prepared biosorbents were characterized by FT-IR, XRD, FE-SEM associated with EDX, HR-TEM, TG analysis, BET surface area analysis and XPS. The maximum specific surface area of 35.22 m2/g was reached. An attempt to use of these magnetic biosorbents for the removal of heavy metal like Cr(VI) from aqueous solution was envisaged.

Abundance and Source Identification of Polycyclic Aromatic Hydrocarbons in Sediments of the Ivory Coastal Zone (Toukouzou Hozalem-Assinie)

Polycyclic aromatic hydrocarbons (PAHs) are strongly associated with agricultural, residential, transportation, industrial and petroleum activities. In this study, the presence of PAHs (polycyclic aromatic hydrocarbons) was investigated in sediments of the ivory coastal zone (Toukouzou Hozalem-Assinie). The main objectives of this study were to determine the abundance and to predict the source of PAHs in the sediments. Gas chromatography-mass spectrometry (GC-MS) was used to analyze sixteen priority PAHs. Total PAHs concentrations were from 1.31 to 3992.68 mg/kg in sediment with an average concentration of (307.54 ± 16.10) mg/kg. Among all PAHs, Naphthalene (Nap = 332.72 mg/kg) and Phenanthrene (Phe = 41.75 mg/kg) were found in the highest concentration, whereas Benzo (k) Fluoranthene was found in the least concentration in the range of 0 - 0.85 mg/kg (mean 0.24 mg/kg). Bassam-Modeste Lagune (BML) sampling site was the site with the highest concentration of total PAHs (all 16 PAHs) compared to the others due to their location in a highly populated estuary area that receives commercial, tourism, port, petroleum and heavy industrial activities. Diagnostic ratios were used to determine the sources of PAHs and suggested that the PAH profile in the sediments was dominated by 2 and 3 ring PAHs. The patterns of PAH compounds in sediment indicated that contamination is from mixed sources, with a strong indication of petrogenic contamination potentially from spills of fuel, oil and industrial activities.

Differential Pulse Voltammetric Simultaneous Determination of Paracetamol and Omnipaque on Boron Doped Diamond Electrode: Application to Natural Tomato, Carrot, Cucumber Juices and Wastewater

This article describes the use of a boron-doped diamond electrode (BDDE) as an electrochemical sensor for the simultaneous determination of omnipaque (OMP) and paracetamol (PCM) in perchloric acid medium (HClO4 0.1 M) and in complex matrices such as tomato, carrot and cucumber juices and waste water from the Treichville University Hospital. Voltammetric studies allowed us to have well-defined oxidation peaks at distinct potentials of OMP (E = 0.5 V/SCE) and PCM (E = 0.7 V/SCE). Under optimized conditions, well-defined quantities of OMP and PCM, introduced simultaneously by metered additions, gave linear responses in concentration ranges of 259.8 - 467.2 μM for OMP and 58.73 - 116.3 μM PCM. The detection limits obtained are 7.23 μΜ and 3.6 μΜ respectively for OMP and PCM with recovery rates between 85.8% ± 0.1% and 92.6% ± 0.1% for OMP and between 99.9% ± 0.1% and 101.2% ± 0.4% for the PCM. This technique has been successfully used to simultaneously detect these pharmaceuticals in these complex environments. It allows recovery of OMP and PCM respectively up to 97.5% ± 0.0% and 91.6% ± 0.3% in tomato juice;100.0% ± 0.0% and 95.2% ± 0.2% in carrot juice;101.4% ± 0.1% and 97.3% ± 0.3% in cucumber juice;100.1% ± 0.9% and 100.9% ± 0.1% in wastewater. The relevance of this technique for the simultaneous detection of OMP and PCM in tomato, carrot, cucumber juices and in waste water can be studied in the context of the contamination of certain fruits and vegetables by the substances organic pharmaceuticals released into the environment without prior treatment.

Kinetic and Thermodynamic Study of the Dephosphation of Wastewater by Clay Materials from Côte d’Ivoire

Phosphorus is introduced into the aquatic environment from different point sources, mainly by domestic and industrial wastewater;contributing to the eutrophication of water bodies. The most common way for wastewater dephosphation is the injection of expensive chemicals into these bodies of water. Thus, the main objective of this work was to find an alternative to chemicals by using clay materials from Côte d’Ivoire to adsorb phosphate ions from aqueous solutions. The clay samples, taken from various regions were characterized by X-ray diffraction. They have a different mineralogical composition. The influence of various parameters such as the pH of the medium, contact time, the ion force, temperature, etc. on the adsorption was studied. Adsorption is influenced by the temperature, the pH of the medium, valence of the saturated cation and the clay composition. It is described by a kinetic model of the pseudo-second order. The salt of the medium has no significant effect on the process. The thermodynamic study revealed that adsorption is spontaneous, endothermic and that it is done by electrostatic means of physical nature.

The Oryzenin’s Effect on Di, Tri and Quadri-Saccharide Degradation. An Investigation by a Mixed Method: ONIOM (DFT/B3LYP/6 - 31 + G(d, p): AM1)

The paddy rice degradation remains a concern for research;the chemical phenomena underlying this process persists unknown. This research aims to identify the mechanism of starch degradation. It determines the nature of the reactions between two, three and four synthons of amylose with oryzenin using theoretical methods. The ONIOM (DFT/B3LYP/6 - 31 + G(d, p): AM1) level of theory is performed on four monomers and eight complexes. Frequencies make it possible to obtain energy and spectroscopic quantities. Calculations after geometry optimization. Following this, a “single point” allows exploiting the “Natural Bond Orbital (NBO)” analysis. The first three parameters suggest that the main interactions between oryzenin and amylose arise through O29-H30…O46 hydrogen bonds (HB). Furthermore, this result posits that the length of the amylose doesn’t influence this reaction. The NBO analysis shows that this component of starch degrades first at the end of the chain to produce monosaccharides;it can also alter in the middle of the chain to give disaccharides.

Experimental and Theoretical Investigations on Copper Corrosion Inhibition by Cefixime Drug in 1M HNO₃Solution

Cefixime, a third-generation semi-synthetic cephalosporin antibiotic was used as a copper corrosion inhibitor in 1M HNO3 solution. The study was conducted through the weight loss technique at 298 - 318 K and theoretical studies based on quantum chemistry. The studied drug inhibited the corrosion of copper in 1M HNO3 over the cefixime concentration range (0.02 - 2 mM). The inhibition efficiency increased with an increase in the inhibitor concentration to reach 91.07% at 2 mM, but decreased with an increase in temperature. The thermodynamic functions related to the adsorption of cefixime on the copper surface and that of the metal dissolution were computed and analyzed. The results point out spontaneous adsorption, mainly through a physisorption mechanism following Langmuir adsorption isotherm model and an endothermic dissolution process. Quantum chemical calculations were also performed at B3LYP level with 6-31G (d, p) basis set and lead to molecular descriptors such as EHOMO (energy of the highest occupied molecular orbital), ELUMO (energy of the lowest unoccupied molecular orbital), ΔE (energy gap) and μ (dipole moment). The global reactivity descriptors such as χ (electronegativity), χ (global hardness), S (global softness), and ω (electrophilicity index) were derived using Koopman’s theorem and analyzed. The local reactivity parameters, including Fukui functions and dual descriptors were determined and discussed. Experimental and theoretical results were found to be in good agreement.

New C-13 Norisoprenoids and Flavonoids from Lannea kerstingii

Lannea kerstingii is known for its multiple therapeutic and biological activities. Despite of many traditional uses of this plant, scientific research on the content of its chemical compounds is still limited. This study aims to isolate the chemical compounds contained in the n-butanol fraction of Lannea kerstingii leaves. The chemical investigation of the leaves of Lannea kerstingii led to isolation of three undescribed C-13 norisoprenoids, lankerstinol A-C (1-3), together with six (4-9) known flavonoid glycosides. The structures of these compounds were established by spectroscopic analyses.

Mechanism of Degradation of Rice Starch Amylopectin by Oryzenin Using ONIOM Quantum Calculations [DFT/B3LYP/6-31+G(D, P): AM1]

Understanding the molecular factors of rice degradation during its aging concerns our research team. This article emphasizes oryzenin-amylopectin. It aims to reveal the mechanism of amylopectin deterioration during rice aging. The research exploits the Natural Bond Analysis and ONION method at theory level DFT/B3LYP/6-31+G(d, p) and AM1. This methodological approach allows highlighting amylopectin transformation;oryzenin converts amylopectin into amyloidosis in continuous. This led to monosaccharides and disaccharides.

Synthesis and Antibacterial Activities of New 2-(Benzylthio)pyrimidines and 2-(Benzimidazolylmethylthio)pyrimidines Derivatives

A series of 2-(benzylthio)pyrimidines (6a-l) and 2-(benzimidazolylmethylthio)-pyrimidines derivatives (6m and 6n) analogues of ethyl 2-(benzylthio)-6-methyl-4-phenyl-1,4-dihydropyrimidine-5-carboxylates and ethyl 2-(((1H-benzimidazol-2-yl)methyl)thio)-6-methyl-4-phenyl-1,4-dihydropyri-midine-5-carboxylates were prepared and evaluated for antibacterial activity. These compounds were obtained by condensation of 2-thiopyrimidines (4) with benzyl halides or 2-(chloromethyl)-1H-benzimidazole (5) in the presence of a base. All compounds were characterized by 1H, 13C and HRMS spectra. Out of fourteen, only eight compounds were screened against multi-resistant strains of Escherichia coli and Staphylococcus aureus. The results revealed that all of them were found to possess significant antibacterial activity against the germs tested. Compounds 6c, 6d, 6h and 6m were more active on S. aureus and compounds 6h and 6m more active on E. coli.

Photocatalytic and Antimicrobial Properties of [AgTiO₂]:[Clay] Nanocomposite Prepared with Clay Different Ratios

This work aimed to synthesis a novel material that would be able to efficiently remove both organic and microbiological pollutants from wastewater. Through the hydrothermal process, we first doped titanium dioxide, a semiconductor possessing excellent photocatalytic properties with silver nanoparticles having good antibacterial properties. The obtained material was then associated with clay known for its good adsorbent properties to form [AgTiO2]:[clay] type nanocomposites. The different mass composition of [AgTiO2]:[clay] considered in this work were 1:1;1:0.5;1:0.1;1:0.05 and 1:0.01. The prepared nanocomposites were characterized by means of XRD, FTIR and SEM techniques. Results revealed the presence of TiO2 anatase and Ag on the surface of the clay mainly composed of kaolinite and quartz. The photocatalytic activities of the nanocomposites were tested in the presence of synthetic Orange II (25 mg/L) wastewater under visible light irradiation. The experiments demonstrated that organic pollutants were effectively photodegraded when the proportion of clay in the mixture (AgTiO2)-(Clay) was inferior or equaled to 50%. The use of commercial TiO2, for comparison purpose, showed a lower degradation efficiency of the Orange II solution (η < 30%). The antibacterial properties of the nanocomposites [AgTiO2]:[clay] were also assessed in the presence of two types of bacteria E. coli (Gram negative) and S. aureus (Gram positive). The antibacterial activities of the nanocomposites were characterized with and without UV irradiation. In dark conditions, the antibacterial activities of nanocomposites (AgTiO2)-(Clay) against S. aureus gradually increased with increasing the clay amount. Under visible light irradiation, the nanocomposites showed a significant antimicrobial activity against E. coli and S. aureus.

Assessing Levels and Health Risks of Fluoride and Heavy Metal Contamination in Drinking Water

A systematic study was carried out to assess the level of contamination with fluorides and heavy metals in the drinking water of the city of Daloa as well as the risks to the health of consumers. The waters of 11.11% of the sites sampled exceeded the fluoride limit for drinking water with a contamination index (CI) greater than 0. All the waters recorded concentrations of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn) and lead (Pb) above the recommended values with CI > 0. However, 22.22% of the sites recorded concentrations below the standard for zinc (Zn) with IC < 0. The assessment of adverse effects on human health showed that the chronic daily intake (CDI) of fluorine and metals was less than 1 (CDI < 1) for both adults and children except for Zn where the CDI > 1 for children in 22.22% of drinking water studied. HQs have an average of less than 1 for fluorine and greater than 1 for all metals. Moreover, the danger indices have values greater than 1. The incremental lifetime cancer risk (ILCR) and the total ILCR are above the recommended values. These results showed that the drinking water sampled is of poor quality due to higher levels of heavy metals, which can constitute a danger to human health. Long-term use of one of these poor quality waters can lead to cancer in consumers. It is therefore necessary to treat this water in order to eliminate the metals before using it for drinking. This study can help decision-makers and competent authorities in charge of water management.

Design, Synthesis and <i>in Vitro</i>Antibacterial Activity of 2-thiomethyl-benzimidazole Derivatives

A series of novel substituted benzimidazole (7a - n) derivatives were synthesized and characterized by 1H, 13C Nuclear Magnetic Resonance (NMR) spectra and High Resolution Mass Spectrometry (HRMS). The substitution was done in position -1 and -2 by appropriate groups. These compounds are obtained by N-alkylation reaction with thiomethyl-1H-benzimidazole intermediates (5a - g). Design of intermediates (5a - g) was made by condensation reaction between 2-methylbenzimidazole thiourunium salt (3) and functionalized halides (4) in the presence of sodium hydroxide (NaOH). Among the twenty-one compounds synthesized, ten were evaluated for their antimicrobial activity on three bacterial strains namely: Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853. Only E. coli ATTC 25922 was susceptible to the synthesized derivatives 5g, 7f and 7h with a significant antibacterial activity (CMI is between 250 and 500 μg/mL).

Antioxidant Activity Evaluation in a Series of Heterocyclic Compounds Derived from 1,8-Diaminonaphthalene

From (2,3-dihydro-1H-perimidin-2-yl)-phenyl, the substitution of OH group in ortho or para position on the phenyl ring, allows us to synthesize the studied compounds. These three compounds have been characterized by conventional spectroscopic methods (NMR and MS). The interest of this work is to review the antioxidant activity of our compounds. The antioxidant activity screening carried out according to FRAP and DPPH methods revealed significant anti-free radical properties for compounds 1 and 2 even at low concentrations. In contrast to the compound 2, compound 3 for which the OH group is substituted in para position has the lowest activity in both cases. Therefore the para position seems to be the least sensitive position to increase the antioxidant activity of this pharmacophore.

Flavonoid Glycosides from the Leaves of Glyphaea brevis

A new flavonoid, acacetin-7-O-β-D-glucopyranosyl-(1 → 2)-β-D-glucuronopyranoside (1), together with four known flavonoids, apigenin-7-O-β-D-glucopyranosyl-(1 → 2)-β-D-glucuronopyranoside (2), acacetin (3), acacetin-7-O-β-D-glucuronide (4) and genkwanin-5-O-primveroside (5) were isolated from the leaves of Glyphaea brevis. Their structures were elucidated by spectroscopic techniques. The isolated compounds (1 - 5) were tested for their antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. The tested compounds showed slight negative antioxidant activities against DPPH radicals.

Retention Factors for Trace Metal Elements in Solid Phase and Applicable Adsorption Models: Case of <i>Moringa oleifera</i>

Moringa oleifera is an edible plant cultivated throughout the tropical belt. It belongs to the family Moringaceae and is one of its 14 known species. This paper presents a synthesis of the main factors responsible for the retention of trace metal elements (TMEs) by Moringa oleifera seed powder, a natural adsorbent. The five main factors studied are metal concentration, solution pH, adsorbent particle size, adsorbent dose and adsorbent/adsorbate contact time. Through these factors, we present the optimal conditions for removal of these TMEs, as well as adsorption isotherm models appropriate for the conditions of retention of these metal cations by the adsorbent. The times of 20 min (GD) and 50 min (GND) are the equilibrium times obtained in our study. An optimal adsorbent mass (GD and GND powders) of 4.5 g was found. 20% to 97% abatement is observed for average pH values between 6 and 8. The coefficients of determination (R2) obtained (0.972, 0.963, 0.991 and 0.799) during the isotherm experiments carried out at 20°C, 30°C, 40°C and 50°C are close to 1. Also, the separation factor (RL), an essential characteristic of the Langmuir isotherm whose values are between 0 and 1, attest to the applicability of the Langmuir isotherm model to fit the experimental data of copper adsorption by Moringa powders. In this paper, we are particularly interested in the following TMEs (Mn, Ni, Cr, Cu, Cd, Co, Pb, Fe, Zn, Ag).

Novel Mannich Bases of Benzimidazole Derivatives: An Antibacterial Study of Environmental Bacterial Strains

A previous study was conducted on the synthesis and antibacterial evaluation of Mannich bases of 2-(thioalkyl)-1H-methylbenzimidazole derivatives. The results of this study showed that certain 2-(thioalkyl)-1H-methylbenzimidazole and 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl)benzimidazole derivatives possess antibacterial activities against clinical strains, such as Escherichia coli, Klebsiella pneumonia (Gram-negative bacteria), Staphylococcus aureus and Pseudomonas aeruginosa (Gram-positive bacteria). Following these favorable results, we extended the antibacterial evaluation of this series of molecules to environmental strains. The aim of this study was to assess the impact of the methyl-piperidine group fixed at position-1 of this new series of benzimidazoles on the antibacterial activity of environmental strains. In addition, we first evaluated the antibacterial activity of four 2-(thioalkyl)methylbenzimidazole derivatives and then that of five 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl) benzimidazole derivatives. This study allowed us to show that compounds 1d and 1e could inhibit bacterial growth in vitro of the Enterobacteria P1 strain with inhibition diameters of 17.3 ± 0.6 mm and 10 ± 0.0 mm, respectively. However, addition of methyl-piperidinyl in this series showed that five (5) of 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl) benzimidazole derivatives had an inhibitory effect on the in vitro growth of bacterial strains used except on Enterobacteria P2 with inhibition diameters between 10.0 ± 0.8 mm and 27.9 ± 1.4 mm. The introduction of the methyl-piperidinyl group at the 1-position of 2-(thioalkyl)-1H-methylbenzimidazole derivatives greatly improved the antibacterial activity against environmental bacteria such as Escherichia coli A1, A2, A3, and A4 and two Enterobacteria P1.

Phytochemical Constituents of the Stem Barks of Uvaria tortilis, an Endemic Annonaceae from Côte d’Ivoire

Uvaria tortilis is a lianescent annonaceous species endemic to the C&#244te d’Ivoire where it is used to treat amenorrhea and as uterotonic. Thus, the MeOH crude extract of its stem barks was investigated in order to determine the chemical composition. A new C-benzyl hydroxlated, uvriatortilisin (1), together with six known compounds, dichamanetin (2), β-sitosterol (3), stigmasterol (4), chamanetin (5), uvaretin (6) and (-)-epicatechin (7), were isolated. Structure of these compounds was elucidated using spectroscopic techniques, including IR, UV, MS and NMR (1D and 2D). Certain compounds could be considered to have chemotaxonomic value.

Design, Synthesis and Antibacterial Activity Evaluation of 4,5-Diphenyl-1<i>H</i>-Imidazoles Derivatives

Due to the continuous emergence and rapid spread of drug-resistant strains of bacteria, there is an urgent need for the development of novel antimicrobials. Along this line, the synthesis and antibacterial activity of 4,5-diphenylimidazol-2-thiol derivatives 2a-g and 6a-e are reported. The structures of the synthesized compounds were confirmed by Nuclear Magnetic Resonance (NMR) and High Resolution Mass Spectrometry (HRMS). All compounds were screened in vitro for their antibacterial activity against Pseudomonas aeruginosa and Escherichia coli (Gram-negative bacteria) and also against Staphyloccocus aureus and Enterococcus faecalis (Gram-positive bacteria). The results showed most of the synthesized compounds have no antibacterial activity. However compound 6d was two-fold potent than ciprofloxacin against Staphylococcus aureus with Minimum Inhibitory Concentration (MIC) of 4 μg/mL and 6c showed moderate biological activity against Staphylococcus aureus (16 μg/mL) and Enterococcus faecalis (16 μg/mL).