European Journal of Chemistry
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Physicochemical characterization of siliceous sands of Seme-Podji/Benin: An application for the synthesis of silica particles
Full text linkIn order to valorize locally available natural resources, the silica sand in the commune of Sèmè-Podji in Republic of Benin was characterized. The results obtained by particle size, chemical analysis, X-ray diffraction (XRD), and FT-IR analysis confirmed that these sands contain a high percentage of silicon dioxide, with a value approximately equal to 90 wt.%. Low Fe2O3 and Al2O3 content (<1 wt.%) and minor oxides such as K2O, Na2O, TiO2, and P2O5 (<0.6%) were also present. The size distributions of the particles show that the largest portion of the sand is found between 63 and 125 μm. This portion represents the one that contains the most silica. From this sand, silica particles were synthesized by the sol-gel method. The results obtained by X-ray diffraction (XRD), FT-IR analysis, and scanning electron microscopy (SEM) reveal the formation of pure amorphous silica
Redox behavior of aliphatic hydroxamic acid and its iron(III) complexes
Full text linkN-Hydroxydodecanamide (HA12) and its trihydroxamato-iron(III) complex (HA12Fe3) have been synthesized and characterized by various methods including structural determination by single crystal X-ray diffraction and cyclic voltammetry (CV). In order to complete our previous CV study on HA12 and its complexes, our aim was to investigate the variation in redox potential upon changes in concentration and pH. The redox couples previously observed with HA12 and HA12Fe3 at 100 µM shifts towards less positive values when the concentration or pH of the solution increases. These results indicate that oxidation is easier when concentrations are higher and in basic media. The slopes of -0.06 V/pH (in agreement with the theoretical data) and -0.077 V/pH (slightly higher than the theoretical slope) were observed for HA12 and HA12Fe3, respectively. This observation would explain the slower oxidation of HA12Fe3 than HA12
Uptake of selected heavy metals from contaminated waters utilizing cost-effective and environmentally friendly biosorbents prepared from the residues of a traditionally fermented Ethiopian alcoholic beverage (Tella)
Full text linkIn the current study, the adsorption capacity of Tella residues (residues of fermented alcoholic beverage) for quantitative uptake of Cu(II), Cd(II), Zn(II) and Pb(II) was evaluated. Chemical treatment of the local beer residue (LBR) has improved the removal efficiency of the adsorbent, which was achieved at pH = 5, 1.0 g adsorbent, 50 mg/L initial concentration, 180 min contact time and agitation speed of 100 rpm. The adsorption was found to fit the Langmuir adsorption isotherm model, and the theoretical equilibrium capacities were well fitted with the experimental equilibrium capacities, resulting in chemical adsorption (chemisorptions) on the adsorbent surface while the equilibrium kinetics follows the pseudo-second-order. The adsorption capacity (Qo) of LBR decreases in the following order: Zn(II) > Cu(II) > Pb(II) > Cd(II) as metal concentration ranged from 20-200 mg/L. Thermodynamic parameters, including standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to predict the nature of adsorption. The negative values of ΔG° and the positive value of ΔH° indicate that the adsorption process was spontaneous and endothermic. Adsorption capacities were found to increase when the temperature ranged from 25-60 °C. Thus, the findings suggest a promising application of LBR as an alternative low-cost novel adsorbent for the removal of toxic heavy metals from wastewater
Antioxidant and anti-inflammatory potentials of the leaf extracts of Calotropis procera and Enantia chlorantha
Full text linkInflammation and oxidative stress are involved in the aetiology of numerous human diseases. The two processes are interconnected such that one may appear before or after the other, but as soon as one of them appears, the other will. Consequently, targeting the two conditions may aid in the prevention or treatment of associated human diseases, and plants capable of performing the two functions together are of great advantage. This study was aimed at evaluating the antioxidant and anti-inflammatory potentials of methanol and aqueous extracts of Calotropis procera and Enantia chlorantha. The leaves of the two plants were extracted separately in water and methanol using a cold maceration method. Antioxidant activity was evaluated using the Lipid peroxidation (LPO), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP), while the anti-inflammatory properties were evaluated using membrane stabilization and inhibition of protein denaturation assays. Qualitative phytochemical analysis was performed using standard methods. The results of the study showed that the aqueous extract of the two plants demonstrated better antioxidant activity than the methanol extracts. IC50 values of 61.60, 59.12, and 83.07 µg/mL were, respectively, for ascorbic acid, aqueous extracts of E. chlorantha and C. procera, while the methanol extracts of both plants recorded a value >150 µg/mL for DPPH. For LPO inhibition, the IC50 values were 191.79 µg/mL, >150 µg/mL for the aqueous, methanol extracts of C. procera and 228.25 µg/mL, 135.46 µg/mL for ascorbic acid and quercetin used as standards. The aqueous extract of E. chlorantha had a value of 161.95 µg/mL and the methanol extracts had a value >250 µg/mL. For the two anti-inflammatory methods used, the IC50 values for the plant were >250 µg/mL. Phytochemicals such as tannins, flavonoids, alkaloids, terpenoids, and phenols were identified in both plant samples. Overall, the results demonstrated the potential of the plant when used for the treatment of diseases related to inflammatory and oxidative stress
Design and synthesis of new coumarin-1,2,3-triazole hybrids as new antidiabetic agents: In vitro α-amylase, α-glucosidase inhibition, anti-inflammatory, and docking study
Full text linkThe current study focuses on the synthesis of coumarin-triazole hybrids (7i-t) starting from 4-hydroxy benzaldehyde or 4-hydroxyacetophenone (1a-b) and propargyl bromide. On the other hand, coumarin derivatives (5c-h) were prepared by Pechmann cyclization and treated with sodium azide to give the corresponding 3-azido methyl coumarins (6c-h). Finally, 1,3-dipolar cycloaddition between compounds 6c-h and terminal alkyne 2a-b produces coumarin-triazole hybrids (7i-t) utilizing click chemistry approaches that are high yielding, wide in scope and simple to perform. The structural proofs of the newly synthesized coumarin-triazole hybrids (7i-t) are proved by various spectroscopic techniques, including IR, 1H NMR, 13C NMR, and LC-MS. The synthesized new coumarin triazole hybrids (7i-t) were explored for their antihyperglycemic potential and therefore evaluated for α-glucosidase and α-amylase inhibitory activities along with anti-inflammatory. The results suggest that among the series, compound 7l showed excellent activity with an IC50 value of 0.67±0.014 mg/mL and 0.72±0.012 mg/mL for α-amylase, and α-glucosidase inhibitory potential while compound 7o showed promising anti-inflammatory activity with IC50 value of 0.54±0.003 mg/mL. To support the above findings, molecular docking studies were performed, which confirmed the interaction of the synthesized molecules 7i-t with an effective binding energy of -9.0 to -10.6 kcal/mol at the active site of the enzyme human pancreatic α-amylase (PDB ID: 1B2Y). Therefore, these scaffolds have the potential to function as lead candidates for antidiabetic and anti-inflammatory activities
N-Morpholine-N'-benzoylthiourea as an extractant for Pb(II) and Cu(II) in aqueous media: Crystal structure of bis(N-morpholine-N′-4-benzoylthioureato)lead(II)
Full text linkThe reaction of N-morpholine-N′-benzoylthiourea (L: HBMOR) and lead(II) acetate gave a neutral, stable metal(II) complex of type ML2. The Pb(II) complex crystallized in a monoclinic crystal system with P21/n space group. The complex was further characterized by spectroscopic and microanalytic analyses. The solvent extraction behaviors of Pb(II) and Cu(II) ions were investigated in aqueous media containing HBMOR/CHCl3 as extracting reagents. The solvent extraction of Pb(II) and Cu(II) ions from solutions of varying pH, varying concentrations of mineral acids (HCl, HNO3 and H2SO4), varying concentrations of masking agents (EDTA, KCN and KH[C8H6O4]) and varying concentrations of salting-out agents (NaCl, Na2SO4, KNO3) in chloroform solutions of HBMOR were studied. Pb(II) and Cu(II) ions were quantitatively extracted at pH = 7 in 10 min (HCl = 0.01 M) and pH = 8 in 5 min (H2SO4 = 0.01 M), respectively. The Pb(II) ions were quantitatively extracted with minimal interference from EDTA (0.01 M), KCN (0.50 M), and potassium hydrogen phthalate (1.0 M), while the Cu (II) ions were extracted with EDTA (1.0 M), KCN (1.0 M) and potassium hydrogen phthalate (0.01 M). The order of increasing interference for the extraction of Pb(II) and Cu(II) ions was KCN > potassium hydrogen phthalate > EDTA. Sodium sulfate (0.01 M) in HCl enhanced the extraction of Pb(II) ions, while sodium chloride (0.50 M) in HCl enhanced the extraction of Cu(II) ions. pH0.5 values of 0.67 and 2.70 were obtained for Pb(II) and Cu(II) ions, respectively, indicating that the separation of the two metal ions is favorable with HBMOR
Synthesis, spectroscopic characterization, crystal structure and computational studies of two new N-aroyl-N′-(2,4,6-tribromophenyl)thioureas
Full text linkTwo new compounds, N-benzoyl-N'-tribromophenylthiourea (I) and 4-nitrobenzoyl-N'-tribromophenylthiourea (II), were synthesized and characterized by 1H NMR, 13C NMR, IR, and X-ray single crystal diffraction techniques. The molecular geometry of compounds I and II in the ground state has been calculated by using the density functional theory (DFT) method with the B3LYP/6-311G(d,p) basis set and compared with the experimental data. The calculated results show that the optimized geometry can reproduce well the crystal structural parameters. A detailed vibrational spectral analysis has been carried out, and assignments of the observed fundamental bands have been proposed on the basis of peak positions. The scaled theoretical frequencies show very good agreement with the experimental values. Frontier molecular orbitals energies (HOMO and LUMO), energy gap, and global chemical reactivity parameters such as ionization potential, electron affinity, chemical hardness, and chemical softness have been calculated, and the sites of electrophilic and nucleophilic regions where the molecular interactions likely to happen are identified. The molecular electrostatic potential and thermodynamic properties of the title compounds were investigated by theoretical calculations
Current advancements in CO2 capture using graphene-based materials
Full text linkIn 2023, global CO2 emissions were 37.4 billion tonnes and a 1.1% increase compared to 2022. Although most countries try to decarbonize their economies, oil and gas supplied 52% of the world's energy needs in 2021, and by 2050 it will be 47%. Therefore, in the future, oil and gas will still account for a considerable percentage of the energy sector. However, the continuous release of CO2 into the atmosphere at this rate can result in severe environmental problems. One of the promising approaches to address this issue is CO2 capture. This captured CO2 can then be stored underground or used to produce commercially valuable products. In recent years, graphene-based materials have gained attention in CO2 capture due to their interesting properties, such as high thermal stability and durability. This review focuses mainly on recently published articles on carbon capture using graphene-based materials
