Chemical Papers最新文献

A rapid and simple method was optimized through experimental design and validated for the separation of chromium and manganese with magnetic sorbent of Fe₃O₄@Ag and 2-(2-thiazolylazo)-p-cresol ligand from the effluent of a steel factory. The adsorbed metals on the magnetic sorbent were simply separated using a magnet and collected on filter paper to measure with an X-ray fluorescence device. The infrared spectroscopy, ultraviolet–visible spectroscopy, field emission scanning electron microscopy, and wavelength-dispersive X-ray spectroscopy were used to characterize and follow the steps of the constructed sorbent synthesis. The surface response methodology was used to achieve better figures of merit and more accuracy. Optimal values for the three effective parameters of the response pH, sorbent amount, and sample solution volume were obtained to be 6.0, 4.0 mg, and 50.0 mL, respectively. Under optimum conditions, the detection limits of 0.5 µg mL⁻¹ and 1.6 µg mL⁻¹ for chromium and manganese ions were achieved, respectively. The acceptable linear range of 2.0–100.0 and 5.0–100.0 µg mL⁻¹ was obtained for chromium and manganese, respectively. To show the efficiency of the method, the heavy metals of chromium (20.0 µg mL⁻¹) and manganese (30.0 µg mL⁻¹) were measured with a high accuracy (n = 3), and the recovery was 98% and the relative standard deviation was 2.1% in the real samples of the effluent of a steel factory.

The potential impact of the liquid–liquid extraction technique for the removal and extraction of iron (III) metal ions has been investigated utilizing different basic extractants. In this respect, Octylamine and N,N-dimethylaniline as primary and tertiary amines were employed for the elimination of Fe(III) ions using benzine as a diluent and with the examination of various supportive parameters as solution pH, contact period, extractant concentration, metal ion concentration, diluent type and loading capacity. The solvent extraction results demonstrated that the maximum removal % of Fe(III) was found to be 96 and 92% for Octylamine and N, N-dimethylaniline, respectively, and it was fast, reached equilibrium after 30 min., and optimized at pH 2 with 0.05 M of the utilized extractants. According to the distribution coefficient calculations, two moles of Octylamine extractant are required for the extraction of a mole of Fe(III) ion, while for N,N-dimethylaniline one mole of it is for extraction of a mole of Fe(III) ion. Moreover, the maximum loading capacity of Fe(III) ions in the organic phase after 5 subsequent stages was 49.8 and 45.4 g/L for Octylamine and N,N-dimethylaniline, respectively. Therefore, the proposed system emphasizes and highlights the promising capability for future progress in the field of extraction techniques and wastewater management.

Herein, a bio-inspired synthetic procedure was described for Ag, ZnO, and Ag/ZnO nanocomposites using an extract of Dendrophthoe falcata leaves. The leaf extract functioned both as a reducing and stabilizing agent, making the synthesis totally green. The biogenic nanoparticles (NPs) were characterized by UV–Visible spectroscopy, zeta potential, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The zeta potential measurement showed the presence of negatively charged groups attached to the surface of NPs providing them moderate colloidal stability. The crystalline nature and structure of NPs were confirmed by powder XRD. The evolution of crystalline phase was noted for Ag NPs at room temperature while annealing at 450 °C was essential for both ZnO and Ag/ZnO phases. According to SEM–EDS and TEM data, the Ag/ZnO composite was rich in Ag concentration and nearly spherical Ag NPs were distributed over the surface of ZnO matrix. Furthermore, the antibacterial efficacy of the as-prepared samples was investigated against both gram-positive and gram-negative bacterial strains. The Zn-based mono- and bimetallic colloids demonstrated a higher antimicrobial potency on gram-positive strains than on gram-negative strains.

This paper reports the production of Ni–Zn multilayer alloy coating to improve the anticorrosive behavior of the mild steel material. The deposition technique follows the square wave current pulse technique. Initially, the effect of current densities on the anticorrosive behavior of the Ni–Zn was investigated. Later, the current densities were optimized in different combinations to get a multilayer of Ni–Zn with different degrees of layering. The Ni–Zn multilayer coatings were developed on the surface of mild steel with different numbers of layers by square pulsing current density of 1 Adm⁻² and 3 Adm⁻². The deposited Ni–Zn alloy coating was studied for its electrochemical behavior toward corrosion. Results revealed that the anticorrosive behavior of the multilayer Ni–Zn alloy coating was found to be many folds higher than that of monolayer Ni–Zn alloy coating. The comparison study of corrosion data revealed that (Ni–Zn)_1/3/300 multilayer coatings are less prone to undergo corrosion among all developed monolayer and multilayer coatings. The corrosion rate of (Ni–Zn)_1/3/300 was found to be less and in the range of 0.37 mm year⁻¹ among all developed coatings.

To unleash the crude potential of polyindole (PIN), it is necessary to modify the polymerization technique in a way that a purer form of PIN is obtained with minimal pre- and post-processing. This work emphasizes the chemical oxidative polymerization of indole in the presence of a hydrotrope–tetra n-octyl ammonium bromide (TOAB), which acts as a phase transfer catalyst and encapsulating agent. The inclusion of TOAB resulted in a fine and uniform morphology of PIN with an average diameter of up to ± 100 nm. In addition, the physicochemical properties were analysed using X-ray diffraction and were in line with FESEM and FTIR analysis. The conjugated activity was also distinguished using UV–Vis. Furthermore, the synthesized PIN was also subjected to an electrochemical study, resulting in a higher specific capacitance in order of two or three magnitudes than those synthesized in the presence of a complete or partial organic solvent, or surfactants. To approve these results, a simple asymmetric supercapacitor was fabricated using as-synthesized PIN and activated carbon as electrode material to power electrical watch. The fabricated low-power energy storage device was able to keep the electronic watch on for more than 240 s, attesting the superior charge transfer and ion mobility. Hence, this work offers a new approach to synthesize PIN as binder-free electrode in aqueous mode and demonstrates a promising potential in several energy storage applications.

Toward scaling up magnetic nanoparticle synthesis from laboratories to the industry, this study reports on the development of a multi-nebulizer-based aerosol-assisted system. The developed system consists of three main parts: a sprayer, an electric heater tunnel, and a rotating magnetic collector. The sprayer consists of a peristaltic pump and two homemade glass concentrate pneumatic nebulizers with untreated fused silica capillaries. High purity nitrogen gas was used as the carrier gas for the generation of aerosols of the reagents pumped into the nebulizers. The angle between the two nebulizers was 35°. The electric heater tunnel consists of 6 tungsten filaments covered by cylindrical stainless steel plates. A dimmer was also used to preset the tunnel temperature. The tunnel temperature was measured using an infrared thermometer. The aerosol generated from the sprayer travel inside the hot tunnel (250–330 °C) for the further reaction of the precursor reagents and desolvation of the synthesized nanoparticles. The rotating magnetic collector consists of a cylindrical neodymium permanent magnet located inside a stainless steel cylindrical plate. The cylindrical complex is rotated using a gearbox DC motor to collect the synthesized MNPs exiting from the electric heater tunnel. Using the developed system, Fe₃O_4, CoFe₂O_4, MnFe₂O_4, NiFe₂O₄, and ZnFe₂O₄ were synthesized successfully. XRD, VSM, and FE-SEM analysis were utilized to characterize the synthesized nanoparticles. The SEM images of the synthesized nanoparticles showed that all synthesized nanoparticles were spherical (except for ZnFe₂O₄). The average diameters were 121.13, 43.19, 33.21, 33.28, and 33.63 nm for Fe₃O_4, CoFe₂O_4, MnFe₂O_4, NiFe₂O₄, and ZnFe₂O₄ nanoparticles using the developed method under the optimized conditions for each nanoparticle. As compared with similar methods such as the spray pyrolysis and aerosol-assisted chemical vapor deposition, the developed method can be utilized for the synthesis of magnetic nanoparticles of relatively higher magnetization at lower temperatures.

A new colorimetric method was developed based on gold nanoparticles (AuNPs) as an optical sensor for fluoxetine (Flx) and sertraline (Ser) in aqueous and micellar media. The drugs caused citrate-stabilized gold nanoparticles (Cit-AuNPs) to aggregate due to hydrogen bonding, resulting in alterations in color and absorption spectra. The impact of several parameters such as pH, reaction time, surfactants, and the concentration of analyte was investigated on the aggregation. Visible absorption spectra revealed that the absorption ratios (A₆₅₀/A₅₂₀ and, A₆₃₀/A₅₂₀) were linear with Flx and Ser in the concentration range of 2–22 nM in the aqueous medium. An improvement in the sensitivity and linear calibration range was observed in a micellar medium within 0.1–1.5 nM with a coefficient of determination of 0.999, under optimal conditions. This strategy was used to quantify Flx and Ser with a detection limit of 0.511–0.543 nM in an aqueous medium and 0.041–0.047 nM in a polyvinylpyrrolidone (PVP) micellar medium without any sophisticated equipment. PVP also had a noticeable influence on the stability of the solutions. The anti-interference performance of the Cit-AuNPs-based detection system for the two drugs was good. The method was effectively utilized to quantify Flx and Ser in pharmaceutical preparations, human urine, and blood serum samples due to its good efficiency, rapid reaction rate, and improved sensitivity with relative standard deviations (RSDs) within 1.3%.

Astragaloside IV/β-cyclodextrin inclusion complex (AsIV/β-CD IC) was successfully prepared by low-temperature sedimentation technology. Under the preparation conditions inclusion temperature 60 °C, inclusion time 3 h, core–wall material molar ratio 1:1, and inclusion rate 750 rpm, the optimal encapsulation efficiency reached 81.63%. It was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and thermogravimetric (TGA). Physicochemical characterization of the AsIV/β-CD IC indicated that the complexation of AsIV/β-CD was successful, and the thermal stability of AsIV was improved clearly. Through granulation technology, astragalus saponin granules (ASG) with uniform size from AsIV/β-CD IC were obtained. ASG possessed significant water solubility and storage stability beside fine taste. In addition, ASG demonstrated beneficial bioactivity in antioxidant and antibacterial functions. Antioxidative stress detection showed that ASG could inhibit the increase of malondialdehyde (MDA) content and the decrease of superoxide dismutase (SOD) content in cells caused by lipopolysaccharides (LPS). In addition, in vitro antibacterial experiments of ASG showed that ASG has obvious antibacterial activity against 6 strains, especially the minimum inhibitory concentration (MIC) value of Escherichia coli and Bacillus subtilis reached 12.5 mg/mL.

Graphical abstract

DNA gyrase brings negative supercoils into DNA and loosens up certain positive supercoils that collect during replication and transcription and is a notable antibacterial target. To fight against the menace of antibiotic-resistant bacterial infections, we have employed various computational tools like high throughput virtual screening (HTVS), standard precision (SP) docking, extra precision (XP) docking, and molecular dynamics (MD) simulation studies to identify some potential DNA gyrase inhibitors. A focused library of 5968 anti-bacterial compounds was screened using the HTVS docking protocol of the glide module of Maestro. The top 200 docked compounds were further filtered using SP and XP docking protocols, and their free binding energies were calculated using MM-GBSA studies. The binding and stability of the top two compounds which showed better docking scores than the co-crystallized ligand (Clorobiocin) of DNA gyrase (PDB ID: 1KZN) were further probed by MD simulation of 100 ns using GROMACS. MD simulation study suggested that the compounds AM1 and AM5 form a stable complex with DNA gyrase with a good number of hydrogen bonds. XP docking study showed that interaction with the crucial amino acids for compounds AM1 and AM5 was like the co-crystallized ligand. These compounds were also predicted to be drug-like molecules with good water solubility and excellent absorption profiles. Based on the above studies, herein we report compounds AM1 (1R,3S)-1-(2-((3-(ammoniomethyl)phenyl)amino)-2-oxoethyl)-3-carbamoylpiperidin-1-ium and AM5 (1'S,2 s,4R)-4-ammonio-6-ethyl-1'-methylspiro[chromane-2,4'-piperidin]-1'-ium as potential DNA gyrase inhibitors which can be further developed as a potential lead against the menace of antibiotic resistance.

For the adsorption of methylene blue (MB), novel bio-polymeric matrices prepared from polylactic acid/sodium alginate (PLA/SA) and polylactic acid/sodium alginate/carbon nanoparticle (PLA/SA/CNP) as green adsorbates were prepared in the form of beads. The developed adsorbent was analyzed using scanning electron microscopes and Fourier transform infrared spectrometers. The percentage of adsorbed dye increased with increasing CNP content, and the optimum ratio was 5% wt. The efficiency of the beads' removal and adsorption capacity were evaluated concerning with (adsorbent dosage, contact time, initial pH, and concentration of adsorbate). After 120 min using 50 mg of PLA/SA/CNP beads, the adsorptive removal process for MB dye was determined to have the maximum rate at pH 9. The models of Langmuir and Freundlich were used to illustrate the experimental data. Langmuir models determined the highest adsorption capacity to be 304.88 mg/g.