Morphology selective construction of β-cyclodextrin functionalized Fe3O4-Bi2WO6 nanocomposite with superior adsorptivity and visible-light-driven catalytic activity

Controlled growth of Bi₂WO₆ nanorods with exposed [0 0 1] facets and the fabrication of an Fe₃O₄-Bi₂WO₆ magnetic composite by a microwave-assisted polyol process, were achieved in this study. The adsorptivity and photocatalytic performance of the composite toward sunset yellow dye degradation were greatly enhanced by the β-cyclodextrin cavities on its surface, firmly anchored through a cetyltrimethylammonium bromide linkage. A series of examinations and characterizations were carried out to determine the influence of various factors on the morphological modulation-photocatalytic behavior of the pure Bi₂WO₆ prior to final functionalization. Changing the pH of the precursor solution impacted the formation of 0D, 2D, and 3D structures; however, the presence of hexamethylenetetramine surfactant induced the development of 1D nanorod structure. A reasonable crystal growth mechanism was proposed to elucidate the formation process. Conversely, the mechanism of the activity enhancement of β-cyclodextrin functionalized Fe₃O₄-Bi₂WO₆, compared to that of the non-functionalized samples, could be realized with the assistance of chemical trapping experiments on sunset yellow, and was confirmed on the colorless antibiotic (sulfamethoxazole). The high performance and durability of this composite can be attributed to the facet-dependent activity, large adsorption capacity due to inclusion interactions, enhanced visible light absorption, and efficient charge separation.     

Magnetohydrodynamic (MHD) flows of viscoelastic fluids in converging/diverging channels

The present work is a theoretical investigation of the applicability of magnetic fields for controlling hydrodynamic separation in Jeffrey-Hamel flows of viscoelastic fluids. To achieve this goal, a local similarity solution was found for laminar, two-dimensional flow of a viscoelastic fluid obeying second-order/second-grade model as its constitutive equation with the assumption being made that the flow is symmetric and purely radial. These assumptions enabled a third-order nonlinear ODE to be obtained as the single equation governing the MHD flow of this particular fluid in flow through converging/diverging channels. With three physical boundary conditions available, Chebyshev collocation-point method was used to solve this ODE numerically. Results are presented in terms of parameters such as Reynolds number, Weissenberg number, channel half-angle, and the magnetic number. It was found that these parameters all have a profound effect on the velocity profiles in Jeffrey-Hamel flows. The effect of magnetic field was found to be more striking in that it is predicted to force fluid elements near the wall to exceed centerline velocity in converging channels and to suppress separation in diverging channels. Interestingly, the effect of the magnetic field in delaying flow separation is predicted to become more pronounced the higher the fluid’s elasticity.     

Recyclable Magnetic Camphor Sulfonic Acid: A Reliable and Highly Efficient Ionic Organocatalyst for Benzothiazin-4-One Synthesis in Green Media

Catalysis Letters - Organocatalysts, like a minimalistic biocatalyst, pursue to reduce metal consumption with low cost, and low toxicity targeting to become a green strategy in organic...     

Preparation of synthesized sulfide polymer through phase-transfer catalyzed polycondensation of ethylene dibromide and sodium tetrasulfide: characterization,thermal and rheological properties

Sulfide polymers were obtained through the interfacial polymerization of sodium tetrasulfide and ethylene dibromide. The polymerization process was carried out under interfacial condition using two phase-transfer catalysts: methyl-tributyl ammonium bromide and methyl-tributyl ammonium chloride. The polymer characteristics were examined by attenuated total reflectance- fourier transform infrared spectroscopy, elemental analysis (CHNS/O) and X-ray diffraction methods. Thermal characteristics were investigated by differential scanning calorimetry and thermogravimetric analysis methods. The rheological behavior of the synthesized sulfide polymer during curing reaction, and isothermal time dependency of elastic storage modulus, G^′, at different temperatures and constant shear frequency was studied using a stress-controlled rheometer. Moreover, the solvent resistance of synthesized polymer was investigated through the swelling method.     

The beryllium / strontium doped hydrogen storage alanate nano powders for concentrating solar thermal power applications

Nanopowders with MeH₂ and Me_m:1-7AlH_n:4-7 (Me:Be/Sr) stoichiometry are synthesized with different aluminum: alkaline earth metal (beryllium and strontium) 0.1 atomic weight ratio step. Hydrogen storage nanoparticles (beryllium hydride-strontium hydride-strontium alanate) have orthorhombic crystal structure, with one step dissociation near 150 °C with ~8 wt% hydrogen in alane to one step in BeH₂ at 250 °C with 18 wt%, to a one step in SrH₂ at 240 °C with 2.1 wt%, and two steps in strontium alanate at 147 and 240 °C with 1.1 and 5.1 wt%. Particles are near 20–70 nm with small crystallite sizes about 6–21 nm in all hydride, alanate and residual ((metallic aluminum and beryllium) and alloyed aluminum, AlSr, Al₄Sr, Al₂Sr intermetallic) phases. Results indicate a controllable process for hydride and alanates nanopowders formation with exact dissociation temperatures/hydrogen release. Nanoparticles show consistent reversibility and cyclic behavior without reducing storage capacity, suitable for concentrating solar power applications.     

CO2/CH4 separation using prepared and characterized poly (ether-block-amide)/ZIF-8 mixed matrix membranes

In this study, poly (ether-block-amide) (Pebax-2533) based mixed matrix membranes were prepared by incorporating various contents of synthesized zeolitic imidazole framework (ZIF-8) nanoparticles into the polymer matrix. The membranes were fabricated via a solution casting–solvent evaporation technique. The results of gas permeation through the membranes revealed that the addition of the ZIF-8 into the polymer matrix enhances both permeability and CO₂/CH₄ selectivity values. As an example, for the mixed matrix membrane comprising 25 wt% of ZIF-8, CO₂ permeability and ideal CO₂/CH₄ selectivity values are 269.73 Barrer and 9.31, respectively, while the corresponding values are 187.54 Barrer and 7.25 for the neat membrane.     

Toward an intelligent approach for predicting surface tension of binary mixtures containing ionic liquids

Knowledge of the surface tension of ionic liquids (ILs) and their related mixtures is of central importance and enables engineers to efficiently design new processes dealing with these fluids on an industrial scale. It’s obvious that experimental determination of surface tension of every conceivable IL and its mixture with other compounds would be a herculean task. Besides, experimental measurements are intrinsically laborious and expensive; therefore, accurate prediction of the property using a reliable technique would be overwhelmingly favorable. To do so, a modeling method based on artificial neural network (ANN) trained by Bayesian regulation back propagation training algorithm (trainbr) has been proposed to predict surface tension of the binary ILs mixtures. A total set of 748 data points of binary surface tension of IL systems within temperature range of 283.1-348.15 K was used to train and test the applied network. The obtained results indicated that the predictive values and experimental data are quite matching, representing reliability of the used ANN model for such purpose. Also, compared with other methods, such as SVM, GA-SVM, GA-LSSVM, CSA-LSSVM, GMDH-PNN and ANN trained with trainlm algorithm the proposed model was better in terms of accuracy.