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Three complexes (bpyH)[Fe(pydc)2].4H2O (1), [Co2(pydc)2(μ-bpy)(H2O)4].4H2O (2) and [Ni(pydc)(bpy)(μ-bpy)]4.8H2O (3) were prepared from the reaction between pyridine-2,6-dicarboxylic acid, pydcH2, and 4,4′-bipyridine, bpy, with FeCl2.4H2O, CoCl2.6H2O and NiSO4.6H2O, respectively. The complex (1) crystallizes in the space group $$P\bar 1$$ of the triclinic system and contains two molecules per unit cell. The structure has been refined to a final value for R factor of 0.0355 based on 4922 reflections. The crystal structure shows that Fe(III) is coordinated to two pyridine-2,6-dicarboxylate ligands. The complexes (2) and (3) crystallize in the space group P21/c of the monoclinic system and contain two molecules per unit cell. The structure (2) has been refined to a final value for R factor of 0.0295 based on 2249 reflections. The molecular structure (2), which is a binuclear complex, contains two pyridine-2,6-dicarboxylate ligands, and a 4,4′-bipyridine bridge ligand. The structure (3) has been refined to a final value for R factor of 0.0579 based on 7721 reflections. In this structure, which is a tetramer complex, pyridine-2,6-dicarboxylate and 4,4′-bipyridine fragments act as a tri- and bidentate ligands, respectively. The protonation constants of 4,4′-bipyridine and pyridine-2,6-dicarboxylate, the equilibrium constants for the pydc-bpy system and the stoichiometry, and stability of complexation of this system with Fe3+, Co2+ and Ni2+ ions in a aqueous solution were investigated by potentiometric pH titration method. The stoichiometry of the most complexes species in solution was found to be very similar to the crystalline cited metal ion complexes.

In this work, α-Fe2O3/C nanoparticles were synthesized through single step reaction and coated with mesoporous SiO2. Surface modification of α-Fe2O3/C using mesoporous SiO2 enhance BET surface area from 18.60 to 312.62 m2 g−1 which significantly affect the adsorption characteristics. Prepared SiO2-coated α-Fe2O3/C nanosorbent was characterized by various analytical techniques and used for the MB dye adsorption experiments. Adsorption capacity has shown higher performance for surface-modified α-Fe2O3/C compare to the bare α-Fe2O3/C nanoparticles. Adsorption influencing parameters such as pH, contact time, and effect of initial concentration were investigated. MB dye adsorption kinetics were examined by the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models and found the pseudo-second-order equation well fitted in the obtained results. The maximum monolayer adsorption capacity was found to be 169.5 mg g−1 and follows the langmuir adsorption isotherm model. MB dye adsorbed nanosorbent was successfully regenerated by the heat treatment to demonstrate the 3 adsorption/desorption cycles. Further, Well water, Tap water, and Seawater were spiked with MB dye to check the adsorption ability in the real systems.

Multi-criteria decision making was used to simultaneous optimization of resolution and analysis time of five aromatic diamines in high-submicellar liquid chromatography. The factors studied were the concentration of sodium dodecyl sulfate [SDS], and volume percentage of methanol. The experiments were performed according to a face-centered cube central composite design to map the chromatographic response surface. The chromatographic response functions (CRFs) were formed using two sigmoidal desirability functions and were considered as the responses of design. The sigmoidal functions were used to transform the optimization criteria, resolution and analysis time into the desirability values. The qualities of the obtained chromatograms in each experiment were evaluated using CRF. Then, multiple linear regression (MLR) was used to correlate the obtained CRFs to the experimental factors and their interactions. The obtained MLR model showed good descriptive and predictive ability (R 2  = 0.9492 and F = 14.99). The optimum mobile phase composition for separation of interested aromatic diamines using a C18 column was 0.15 M SDS and 59 % (v/v) methanol. Proper resolutions with a reasonable analysis time were obtained under the optimum condition.

Molecular dynamics simulations and umbrella sampling have been used to investigate the sliding of distamycin anticancer drug along the DNA minor groove. The potential energy surface calculated for the sliding of drug shows three minima. The global minimum corresponds to the binding of drug to the AT-rich region, which is the origin of sequence selectivity of distamycin. This selectivity originates from both structural factors and energy contributions. The analysis of energy contributions of binding was performed by the MM–PBSA method. The analysis of hydrogen bonds and van der Waals, electrostatic, and solvation interactions show that structural or steric factors are more important in the selectivity of distamycin than energetic factors. The results of this study can be applied in the design of new derivatives of distamycin anticancer drug with improved properties.

In this work, a new composite photocatalyst, combined with Ag3PO4 and AgSbO3 (AZA Catalyst), was elaborately designed, successfully synthesized, and characterized by many techniques, such as XRD, UV-DRS, SEM–EDS, XPS, and TEM. Then, the AZA Catalyst was applied for the photocatalytic degradation of Methylene Blue (MB) and tetracycline. The results showed that AZA Catalyst could effectively degrade MB and tetracycline, and the degradation efficiencies were better than that of sole Ag3PO4 and AgSbO3. The photocatalytic properties of AZA Catalyst also exhibited excellent stabilities. In addition, the active species of ·OH and ·O2− were demonstrated in the photochemical reaction and played a crucial role to the photocatalytic reaction. Moreover, with the help of advanced characterization (XRD, XPS, ESR, PL, electrochemical analysis) and DFT calculation, the photocatalytic degradation mechanism illustrated that Ag produced in the process of reaction constructed a typical Z scheme path (Ag3PO4/Ag/AgSbO3). Furthermore, due to the work function differences among Ag3PO4, AgSbO3, and Ag, the photogenerated electrons and holes could be effectively transferred and decreased the recombination probability of electrons and holes and thus accelerated the photocatalytic efficiencies of pollutants.

The successful growth of an efficient binder-free VS2-NiS2 hybrid electrocatalyst on graphite rods is reported in the research via a facile one-pot hydrothermal method. According to the field emission scanning electron microscope images, the size of sheets and shape of structures are altered by increasing the concentration of NiS2, influencing the active sites and electrochemical results. The optimum VS2-NiS2 hybrid nanostructure catalyst offered a low overpotential (77 mV) at − 10 mA.cm−2, small Tafel slope (44.86 mV.dec−1), and negligible overpotential alteration after 1500 successive CV (cyclic voltammetry) cycles. The enhanced electrocatalytic activity of hybrid can be attributed to more exposure of active sites, adjustment of the binding energy of hydrogen to the surface, and improved charge transfer kinetics. This study offers a novel, cost-effective, binder-free, stable, and high-performance VS2-based nanostructured HER (hydrogen evolution reaction) electrocatalyst.

The morphological and mineralogical composition of a termite mound from Ilorin, Nigeria was investigated with a view to understand its sorption properties. The termite hill soil was subjected to some spectroscopic analyses such as X-ray fluorescence (XRF) and Scanning Electron Microscopy. The XRF results revealed that the adsorbent contains a large fraction of Silicon, Iron and Aluminium minerals. The organic matter (OM) content expressed as percentage carbon was 3.45% while the high value of cation exchange capacity of 14.0 meq/100 g is in agreement with high percentage OM, which signifies high availability of exchangeable ions. The maximum Pb(II) adsorption capacity of the mound was found to be 15.5 mg/g. Batch adsorption experiments were carried out as a function of contact time, ionic strength and pH. Maximum and constant adsorption was observed in the pH range of 2–5.5. The experimental results of Pb(II) adsorption were analyzed using Langmuir, Freundlich, and Temkin isotherms. The Langmuir and Temkin isotherms were found to fit the measured sorption data better than Freundlich. The constants obtained from the Langmuir model are maximum sorption value, Q m = 18.18 and Langmuir energy of adsorption constant, b = 0.085, while the constants of the Freundlich model are the intensity of adsorption constant, n = 0.134, and maximum diffusion constant, K f = 1.36. The adsorption data for Pb(II) was found to fit well into the pseudo-second order model. Desorption experiment was conducted using different concentrations of leachant and this was repeated three times to determine the life span of the adsorbent. It was observed that 0.2 M HCl had the highest desorption efficiency for reuse.

The textile industries release a substantial amount of effluents into water resources every year. The vast majority of these effluents are composed of heavy metals that bind the textile fibres with dyes. This work proposes to use an adsorption system composed of clay-minerals (kaolinite and montmorillonite) and molecular sieve (zeolite) for separating the Cu2+ and Cr6+ ions, considering the pH changes of aqueous solutions. The adsorbent materials were characterized using the following state of the art techniques such as X-ray fluorescence, X-ray diffraction, Raman spectroscopy and Cation exchange capacity. During the adsorption tests, the contact time of the adsorbates (Cu2+ and Cr6+ ions in concentrations of 100, 50, 10 and 5 mg/L) with the adsorbents vary from 1 to 4 h in acidic and alkaline conditions (pH 3.5 and 7.5). The results indicate maximum adsorption of Cu2+ (at pH 3.5) and Cr6+ (at pH 7.5) ions on application of the zeolitic material. The clay minerals conclusively proved to be less efficient when compared to zeolite. It can be concluded that the adsorption system has achieved the desired efficiency, with substantial removal of Cu2+ and Cr6+ ions for zeolites in synthetic wastewater solutions of the textile industry.

ZnO nanoparticles with an average particle size of 27 nm were fabricated using a microwave-assisted sol–gel method in the presence of ethylene glycol. The nanoparticles were characterized by X-ray diffraction, Monshi’s equation, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The band gap energy of the nanoparticles was measured to be 3.27 eV by UV–Vis absorption and reflection spectroscopy. Photocatalytic activity of the synthesized nanoparticles was assessed by degrading nitrophenol in aqueous solution under UV-C irradiation. The effects of initial nitrophenol concentration, amount of photocatalyst, and of pH on the photodegradation process were investigated. Degradation samples were analyzed by UV–Vis spectroscopy. Nitrophenol was removed by 98 % within 240 min. The degradation kinetics were studied and fitted well to pseudo-first-order and Langmuir–Hinshelwood models.