Exploitation the unique acidity of novel cerium-tungstate catalysts in the preparation of indole derivatives under eco-friendly acid catalyzed Fischer indole reaction protocol

Investigation of g-C3N4/Ce2(WO4)3 Nanocomposites for the Removal of Basic Dyes

Herein, we have synthesized pristine and g-C3N4-assisted Ce2(WO4)3 via a facile hydrothermal method. The structure was confirmed with the standard JCPDS card. g-C3N4 encapsulated the crystal and reduced the size. The Raman spectra revealed the presence of Ce-O, W-O stretching and bending vibrations. Electron hole transfer facilitation and controllable recombination were altered by g-C3N4 heterojunction with cerium tungstate. Ce2(WO4)3 possessed a larger band gap. As g-C3N4 was assisted, the band gap was reduced which facilitates Ce2(WO4)3 to utilize more visible light. The prepared photocatalysts were used to investigate the model pollutant removal with visible light. The pure Janus Green B sample showed lesser efficiency, as it does not show self-degradation under light. As Ce2(WO4)3 was added, it slightly improved the efficiency as it possesses lower electron hole transfer and high recombination. Thus, g-C3N4 was composited with Ce2(WO4)3 to make heterojunctions which will enhance the photo-excited electron and hole transfer and decrease e-/h+ recombination. The rate constant values of the photocatalysts were calculated, and the system follows the first-order pseudo-kinetic model. Ciprofloxacin, a well-known antibiotic, was also used to degrade under visible light. The pure sample showed lower efficiency, and the antibiotic was reduced well with the addition of prepared photocatalysts. The modification of Ce2(WO4)3 with the optimum-level g-C3N4 facilitated electron hole charge transfer, and numerous adsorbed dye molecules on the photocatalyst surface made 0.1 g g-C3N4-Ce2(WO4)3 a plausible photocatalyst for the water remediation process.

Green synthesis of thiourea derivatives from nitrobenzenes using Ni nanoparticles immobilized on triazine-aminopyridine-modified MIL-101(Cr) MOF

Nanohybrid metal-organic frameworks (MOF) have recently been considered next-generation catalysts regarding their unique features like large surface-to-volume ratio, tailorable geometry, uniform pore sizes, and homogeneous distribution of active sites. In this report, we address the triazine-aminopyridine-modified 3D Cr-centred MOF MIL-101(Cr)-NH2 following a post-synthetic modification approach. The excellent chelating ability of triazine-aminopyridine was applied to immobilize Ni ions over the host matrix MOF. The as-synthesized material was physicochemically characterized using various analytical techniques like FT-IR, electron microscopy, EDS, elemental mapping, XRD, and ICP-OES. Subsequently, the material has been catalytically employed in synthesizing new thiourea derivatives by reacting to nitrobenzene derivatives and phenyl isocyanate. The catalyst was isolated by centrifugation and recycled in 6 consecutive runs without momentous loss of its reactivity.

A Novel Method for Dynamic Molecular Weight Distribution Determination in Organometallic Catalyzed Olefin Polymerizations

In this study, a mathematical model for the time evolution of molecular weight distribution (MWD) was developed. This temporal model is based on the well-known Ziegler–Natta polymerization mechanism and reaction kinetics by the parametric solving of related differential equations. However, due to the generality of the reactions involved, the model can be extended to the other type of catalysts, such as metallocenes, Phillips, etc. The superiority of this model lies in providing the possibility of a more precise prediction over the active sites and kinetic parameters using a simple mathematical equation, which leads to improved reactor design in large-scale production. The model uses a function to develop a methodology for MWD calculations. In this way, the transient response is limited to the first few minutes of the reaction; however, it is important as it demonstrates the establishment of the final MWD. According to the results, almost for practical conditions with negligible transfer resistances, the time dependency of the MWD has a transient interval, depending on the kinetic constants of polymerization reactions. Increasing the time to infinity results in an increase in MW and a widening in MWD, which confirms the experimental plots well. In short, the main advantage of our proposed model over the previous ones is its ability to predict the MWD even before the completion of the polymerization reaction. The results of the present model match well with those of the well-known Schulz–Flory distribution, which only predicts the final molecular weight distribution, thus confirming that the model is reliable and generalizable.

Gold-selenide quantum dots supported onto cesium ferrite nanocomposites for the efficient degradation of rhodamine B

In this work, different weight percentage of gold-selenide quantum dots (AuSe QDs) (1.0, 2.5, 5.0 and 7.0 wt.%) were successfully synthesized and decorated on cesium ferrite nanocomposite (Cs2Fe2O4 NC). The as-prepared pure AuSe QDs, pure Cs2Fe2O4 NC, and x wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts were investigated using different characterization techniques such as nitrogen adsorption desorption isotherms (BET), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. The results show that AuSe QDs were uniformly distributed on Cs2Fe2O4NCs surface as spherical dots with an average size of 1.0-8.0 nm. While the Cs2Fe2O4 NCs possess an average size between 10 to 35 nm. The photocatalytic performance of x wt. % AuSe QDs/Cs2Fe2O4NCs were measured through the photodegradation of rhodamine B (RhB) dye as a model water pollutant, under a150 W-Mercury lamp with a filter (JB400) as a simulated source of visible light. The results revealed that the % degradation of RhB increased from 50.0 %, 59.1 %, 76.4 %, and to 99.15 % within 150 min for the pure Cs2Fe2O4, 1.0, 2.5 and 5.0 wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts, respectively. The 5.0 wt.% AuSe/Cs2Fe2O4 NC sample showed highest photocatalytic activity. The effect of recycling also studied. High photocatalytic performance and superior stability confirmed that the prepared nanocomposites act as good photocatalysts.