Turkish Journal of Chemistry最新文献

The effect of synthesized 5-((4-hydroxy-3,5-di-tert-butylphenyl)diazenyl)isophthalic acid (HBA) containing a hindered phenol derivative on the thermooxidation, hydrochloric acid release time, and mechanical strength of PVC/CuO nanocomposites was studied. Moreover, 5-((4-hydroxy-2,5-dimethylphenyl)diazenyl)isophthalic acid (HMA) was synthesized for comparison of corresponding PVC nanocomposite properties. PVC nanocomposite thin films were prepared through in situ surface modification of CuO nanoparticles with HBA and HMA, individually, in the PVC solution. The XRD and FE-SEM results clarified the desirable dispersion of CuO nanoparticles. The PVC sample with loading of 5 wt% from each HBA and CuO was found to be the most thermally stable, which was confirmed by thermogravimetric analysis in inert conditions. The thermooxidation and Congo red test results revealed that the simultaneous loading of HBA and CuO nanoparticles into the PVC matrix could increase the initial thermal degradation and the stability times. Moreover, the PVC sample containing 2.5 wt% each from HBA and CuO nanoparticles exhibited tensile strength almost 20 MPa more than that of neat PVC.

This study investigates the preparation and properties of aniline polymerized in situ onto a nanosized TiO₂ surface to form core-shell nanoparticles at ambient temperatures. The in situ polymerization of aniline to polyaniline (PANI), in conjunction with the utilization of an anionic surfactant, was employed in this investigation. The prepared PANI-TiO₂ core-shell nanoparticles were integrated with chitosan at a gravimetric ratio and cast as core-shell nanocomposite membranes. The nanocomposites were subjected to structural analysis using Fourier transform infrared spectroscopy and X-ray diffraction patterns. The surface morphologies of the PANI and its nanocomposites were analyzed using scanning electron microscopy. Direct current conductivity studies revealed three discrete tiers of conductivity intrinsic to a semiconductor material. The nanocomposite, comprising a chitosan membrane embedded with 4 wt.% PANI-TiO₂, demonstrated peak direct current conductivity of 5.7 S/cm. The properties of the core-shell nanocomposite membranes could be elucidated using cyclic voltammetry, a technique that allowed for the observation of redox peaks occurring at 0.94 V and 0.25 V. The presence of both peaks was due to the redox transition of the prepared nanocomposite membranes from a semiconducting to a conductive state. At room temperature, the hydrogen absorption capacity was approximately 4.5 wt.%, but when the temperature was raised to 65 °C, it doubled to about 7.5 wt.%. In comparison to other nanocomposites, the 4 wt.% PANI-TiO₂ core-shell embedded chitosan membrane exhibited significantly higher absorption capacity of 10.5 wt.%.

Bimetal nanocatalysts hold significant application potential in catalytic reactions due to their compositions, morphologies, and electronic structures. In the present work, a series of AuPd alloy dendrites were successfully prepared using sodium formate, without surfactants or templates. A systematic investigation was then conducted to analyze the composition of the AuPd bimetallic dendrites and the effects of preparation conditions on their structure and catalytic performance. The AuPd alloy dendrites were characterized through various techniques, including scanning electron microscopy, transmission electron microscopy, X-ray energy scattering spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that the Au:Pd ratio in the AuPd alloy dendrites closely matched the initial feeding ratio. The catalytic activity and stability of the AuPd alloy dendrites towards 4-nitrophenol reduction were remarkably higher compared to those of the single metal Au and Pd nanocatalysts. Specifically, the Au₁Pd₁ alloy dendrites exhibited the highest catalytic reduction activity for 4-nitrophenol, with a reaction rate constant of 1.05 × 10^-2. Moreover, the stability of the Au₁Pd₁ alloy dendrites was also examined. The results demonstrated that the catalytic stability of the Au₁Pd₁ alloy dendrites did not experience a significant decrease even after five cycles of operation.

The removal of color arising from water-soluble dyes in wastewaters is necessary to counter the threat to health. Because of the difficulty in elimination of these dyes by conventional methods, their photodegradation using photosensitizers such as phthalocyanines (Pcs) has been employed recently. When compared to peripherally substituted derivatives, silicon Pcs are reported to be more biocompatible with low toxicity. Thus a new silicon Pc substituted with two quaternized dimethylamino phenoxy units (compound 1) and its quaternized derivative (compound 2) were synthesized to test its photocatalytic ability employing the dyes methylene blue (MB), eosin B (EB), erythrosine (ERB), sulforhodamine B (SRB), and brilliant blue FCF (BRB), some of whose absorption bands overlap with those of Pcs. The overlapped absorption bands were split using first-order derivative UV-vis spectra. The photodegradation rates of BRB, MB, and ERB were 41%, 38%, and 29%, respectively, under 30-s short time irradiation in the presence of compound 2. The plots of the natural logarithm of the concentrations of dyes versus time fit the first-order reaction model. According to the experimental data, compound 2 could be used as a photocatalyst due to singlet oxygen generation for photodegradation of pollutant dyes MB, ERB, and BRB with higher photodegradation rates.

Sex-Determining Region Y-box 2 (SOX2) is a transcription factor protein. SOX2 expression is related to lymph node metastasis and distant metastasis in colorectal carcinomas. SOX2 was determined with the first magnetic disposable immunoplatform. The designed sandwich-shaped immune complexes were formed by a capture antibody, SOX2 protein, and biotinylated secondary antibodies (dAb/HRP). The sandwich-shaped immune complex was linked to carboxylic acid functionalized magnetic beads (HOOC-MBs). This magnetic bioconjugate was dropped on the surface of the screen-printed carbon electrode (SPCE). The amperometric measurement was performed at -0.20 V in the presence of hydroquinone (HQ) and H₂O₂ against a silver pseudo-reference electrode. The optimization parameters affecting the immunoassay response were evaluated. The analytical evaluation of the magnetic disposable immunoplatform for the amperometric detection of SOX2 standards was done. The developed immunosensor shows high sensitivity (LOD of 1.37 ng mL^-1) and a short analysis time (15 min). Potential interfering compounds found in serum samples were tested. The storage stability of magnetic disposable immunoplatform was evaluated. The developed immunosensor was compared with the ELISA method.

Highly effective graphitic carbon nitride-supported RhFe nanoparticles (RhFe/g-C₃N₄) were prepared using a simple wet impregnation-reduction method for the hydrolysis of sodium borohydride (NaBH₄). The obtained Rh_0.48Fe_0.52/g-C₃N₄ catalyst was characterized using advanced analytical/spectroscopic techniques such as inductively coupled plasma-optical emission spectroscopy, scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, X-ray spectroscopy, and Fourier transform infrared spectroscopy. The catalytic activities of RhFe/g-C₃N₄ catalysts with varying Rh/Fe molar ratios were investigated, demonstrating superior catalytic activity compared to monometallic Rh and Fe. The initial turnover frequency value of the Rh_0.48Fe_0.52/g-C₃N₄ catalyst was calculated as 33.04 min^-1 and it showed an H₂ generation rate of $4214.02\hspace{0.17em}\text{mL\hspace{0.17em}}{\text{min}}^{-1}\hspace{0.17em}{\text{g}}_{\text{cat}}^{-1}$ at 298 K. Furthermore, the kinetic parameters (E _a ^#, ΔH ^#, ΔS ^#) of the hydrolysis of NaBH₄ catalyzed by the Rh_0.48Fe_0.52/g-C₃N₄ catalyst were elucidated. The findings demonstrated that the resulting Rh_0.48Fe_0.52/g-C₃N₄ catalyst was recyclable and retained 80.72% of the initial activity even after 10 runs.

A composite electrode was fabricated for simultaneous determination of sunset yellow (SY) and tartrazine (Tz) in foods and syrup. It is based on n-butylamine intercalation into graphite and then dropped on a poly (4-aminophenol)/glassy carbon electrode (GCE). The electrode surface morphologies, chemistry, and electrical properties were identified by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS), and electrochemical impedance spectroscopy (EIS). The new composite electrode significantly increased the electrochemical response of SY and Tz relative to a bare GCE. The peak current of SY and Tz increased linearly depending on their concentrations from 0.006 μmol L^-1 to 1.0 μmol L^-1 (r = 0.994) and over two linear ranges from 0.06 to 1.50 μmol L^-1 (r = 0.9955) and from 2.0 to 10.0 μmol L^-1 (r = 0.9902), respectively. The limits of detection of SY and Tz were 2.60 nmol L^-1 and 0.025 μmol L^-1, respectively (S/N = 3). SY and Tz contents in real samples were determined in syrup, juice powder, and candy. Spiked recovery for samples was from 96.4% to 106.8%. The relative standard deviations were lower than 5.0%.

Chemical compounds in wastewater, including dye molecules, have been identified as significant concerns for environmental integrity and human health. In this study, adsorbent materials were synthesized from biodegradable polymers to remove methylene blue (MB) from wastewater. Calcium alginate hydrogels were produced and coated with chitosan to enhance their pH stability. Furthermore, the calcium alginate gels were doped with silver nanoparticles to improve their photocatalytic properties, promoting MB degradation and enabling gel reuse. The adsorption behavior of the gels was comprehensively examined under dark conditions, considering factors such as time, solid-to-liquid ratio, temperature, and pollutant concentration, all of which significantly impact the adsorption process. The wastewater, containing 100 ppm of MB, was subjected to a cleaning process that resulted in a reduction of the initial concentration by over 95%. Adsorption kinetics, thermodynamic constants, and adsorption isotherms were studied to understand the underlying mechanisms better. It was observed that the adsorption kinetics were compatible with pseudo-second-order with R² values above 0.99 and the adsorption kinetics were compatible with Freundlich with 0.9996. Modeling and simulation studies were used to establish the correlation between adsorption behavior and the concentration of dye material. Subsequently, UV light exposure was applied, enhancing further efficiency and enabling gel regeneration. Even after five cycles, the gels maintained an efficiency of 88.42%. Structural characterizations, pH stability assessments, and cytotoxicity analyses were conducted to evaluate the suitability of the gels for wastewater treatment with minimal environmental or health impact.

In processes such as electrodialysis, the applied electrical potential is constrained by concentration polarization at the membrane/solution interface. This polarization, which intensifies at higher current densities, impedes ion transport efficiency and may lead to problems such as salt precipitation, membrane degradation, and increased energy consumption. Therefore, understanding concentration polarization is essential for enhancing membrane performance, improving efficiency, and reducing operational costs. This study investigates the impact of ammonia buffer (NH₄ ⁺/NH₃) on sulfate ion transport through anion-exchange membranes with a particular focus on limiting current density and concentration polarization under constant current conditions. The findings demonstrate that ammonia effectively eliminates concentration polarization and enhances chemical reactions at the membrane interface. Notably, the plateau region was absent in the current-voltage curves, as was the transition time in the chronopotentiograms. Furthermore, the Warburg impedance arc in the Nyquist plot of the electrochemical impedance spectra was absent in both limiting and overlimiting current regions and the increasing dominance of the Gerischer arc was registered. At an ammonia concentration of 0.1 M, the influence of concentration polarization on mass transport was effectively mitigated, enabling sulfate counterions to pass through the membrane without encountering concentration polarization. The addition of ammonia catalytically accelerated the proton-transfer reactions, which accelerated the water dissociation reaction at earlier polarization stages, preventing the formation of diffusion boundary layers and facilitating the transport of sulfate counterions through the AMX anion-exchange membrane. As a result, the polarization plateau disappeared and the overlimiting current region shifted closer to the ohmic region, all without affecting the limiting current density (j _lim ).

The development of ultraviolet (UV) shielding materials is of great importance to protect human health and prevent the degradation of organic matter. However, the synthesis of highly efficient UV shielding polymer nanocomposites is currently limited by the agglomeration of inorganic anti-UV nanoparticles (NPs) within the polymer matrix and the limited absorption spectrum of UV shielding agents. In this study, highly effective manganese doped carbon quantum dots@halloysite nanotube composites (Mn-CDs@HNTs/PAS) were successfully synthesized by loading manganese-doped carbon quantum dots (Mn-CDs) into UV shielding effective halloysite nanotubes (HNTs) via the solvothermal method, followed by polymerization modification (PAS). The results show that inorganic NPs are evenly dispersed into the polymer matrix. The resulting UV shielding film prepared by mixing Mn-CDs@HNTs/PAS composites with polyvinyl chloride (PVC) shows enhanced UV absorption and thermal stability compared with pure PVC film. It thus appears that Mn-CDs@HNTs/PAS composites have a promising future in UV protection.