Poly (L-phenylalanine-paired ionic liquid) as halogen-free heterogeneous nanocatalyst toward regiospecific 1,3-dipolar cycloaddition reaction

Although amino acid-paired ionic liquids (IL [AA]) have attracted considerable attention due to their environmental-friendly nature and providing abundant catalytic active sites, polymerized eco-friendly ILs have been rarely reported. Herein, we introduce a novel polymerized L-phenylalanine-paired ionic liquid (PIL [Phe]), synthesized in a new smart manner, as a promising heterogeneous nanocatalyst for regiospecific 1,3-dipolar cycloaddition reaction. For this purpose, new polymerizable ionic liquid (3-(3-aminopropyl)-1-vinylimidazolium (L)-2-amino-3-phenylpropanoate ([AVIm][Phe])) was designed and constructed as a halogen-free multifunctional monomer. The successful fabrication of chiral IL was approved by different techniques including ¹H NMR, FT-IR, and elemental analysis. Next, a green precipitation polymerization approach was applied using a water-soluble initiator under mild conditions. Co₃O₄@PIL [Phe] was synthesized by in situ copolymerization of the [AVIm][Phe] with ethyleneglycoldimethacrylate (EGDMA) (as non-ionic cross-linker) supported on magnetic Co₃O₄@MPS. The obtained data reveal that the supported polymerized form of [AVIm][Phe] is more efficient due to the formation of a porous structure with high-specific surface area (235.5 m²/ g) and a cross-linked network with high thermal stability (35% weight loss around 600 °C). In the following, the proposed Co₃O₄@PIL [Phe] nanostructure was applied as a magnetic catalyst toward the preparation of new and reported pyrrolidinyldispirooxindoles; and it displayed accelerated mass transfer due to its large pore volume (0.85 cm³/ g), and numerous accessible active sites. Consequently, a range of pharmaceutical dispirobisoxindole scaffolds with broad structural diversity were readily obtained in excellent yields (>92%) and high regioselectivity under environmental conditions.     

Influence of geometry on separation efficiency in a hydrocyclone

A numerical study of the gas–liquid–solid multiphase flow in hydrocyclones is presented. Three models of turbulence, the RNG k–ε model, the Reynolds stress model and Large eddy simulation with the volume of fluid model (VOF) multiphase model for simulating air core are compared in order to predict axial and tangential velocity distributions. This presentation is mainly aimed at identifying an optimal method, used to study effective parameters, based on which, eventually, effect of inlet flow rate variations and body dimension variations such as underflow diameter, overflow diameter and cone angle on the separation performance and pressure drop are investigated. The results are then used in the simulation of particle flow described by the stochastic Lagrangian model. The results suggest that the predicted size classifications are approximately similar to those of RSM and LES methods. Predictions using the RSM model are found in agreement with experimental results with a marginal error within the range of 4 to 8%. Proceeding model validation, parametric studies have been carried out concerning the influence of velocity inlet, particle size and body dimension such as underflow and overflow diameter and cone angle. The predictions demonstrate that the flow fields in the hydrocyclones with different sizes and lengths are different, which yields different performances.     

DFT Study of Cyanide Oxidation on Ge-Doped Carbon Nanotubes

In recent years, the discovery of efficient catalyst with low price to cyanide (CN) oxidation in normal temperature is a major concern in the industry. In present study, in first step the carbon nanotubes (CNTss) were doped with Ge and the surface of Ge-doped CNTss via O₂ molecule were activated. In second step the CN oxidation on activated Ge-CNTss surface via Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) mechanisms was investigated. Results show that O₂ activated Ge-CNTs surface can oxidize the CN molecule via Ge-CNTs–O–O* + CN → Ge-CNTs–O–O*–CN → Ge-CNTs–O* + OCN and Ge-CNTs–O* + CN → Ge-CNTs + OCN reactions. Results show that CN oxidation on activated Ge-CNTs surface via the LH mechanism has lower energy barrier than ER mechanism. Finally, calculated parameters reveal that activated Ge-CNTss is acceptable catalyst with low price and high performance for CN oxidation in normal temperature.     

Ultra‐deep desulfurization of a model fuel using novel VOHPO4 0.5H2O/boehmite catalysts

A high‐surface‐area boehmite was used as the support for a series of vanadium phosphate catalysts. The catalysts were prepared by heating of V₂O₅ in an isobutyl alcohol and benzyl alcohol mixture at 140°C for 5 h to reduce V⁵⁺ to more active V⁴⁺ in the presence of phosphoric acid. Then a series of catalysts with various VPO loadings on boehmite were synthesized. The catalysts were characterized using various techniques. The catalysts were utilized for extraction combined with catalytic oxidation of dibenzothiophene. The important factors influencing the desulfurization process, including reaction time, temperature, H₂O₂, catalyst loading, catalyst amount and solvents, were systematically investigated. Under the optimized reaction conditions, i.e. 30 mg of catalyst loading at 50°C and in 60 min, sulfur removal reached 94%. The catalyst was recycled and reused five times.     

On the Calculation of the Second Virial Coefficient of Pure Polar and Non-Polar Gases Using van der Waals and Dieterici Models; Temperature-Dependence Covolume Parameter

Russian Journal of Physical Chemistry A - In this paper, we calculate the second virial coefficient of polar and non-polar fluids in order to evaluate the performance of some equations of state...     

Energy,Exergy analysis and performance evaluation of a vacuum evaporator for solar thermal power plant Zero Liquid Discharge Systems

Journal of Thermal Analysis and Calorimetry - Water scarcity and environmental impacts of blowdown within steam power plants are among the important growing concerns. In order to solve these...     

Selective Complexation of S‐block Cations with Nanotubular Silk Type Cyclopeptides: A DFT Study

Density functional theory (DFT) was used to study the interaction of alkali metal cations (Li⁺, Na⁺ and K⁺) with cyclic peptides constructed from silk type macrocycles ( Silk1, Silk2, Silk3, Silk4, Silk5 and Silk6 ). The calculated binding energies were used as a base for investigating the selectivity of the cyclic peptides in biniding to considered metals ions. The highest cation selectivity for Li⁺ compared to the other alkali metal ions was observed. The orbital nature of different interactions between the metal cations and the cyclic peptides was analyzed using NBO analysis. The main types of driving force for host‐guest interactions was investigated and it was found that the electron‐donating O offers lone pair electrons to the contacting LP* of alkali metal cations     

Using the QSPR Approach for Estimating the Density of Azole‐based Energetic Compounds

The relationship between density of energetic azole‐based compounds and their molecular structure is investigated through quantitative structure‐property relationship (QSPR) approach. The methodology of this work introduces a new model, which related density of azole‐based energetic compounds to the optimum elemental composition, the degree of unsaturation (DoU) of the compounds, presence of nitroimino group in the structural formula, as well as several non‐additive structural parameters. The presence of nitroimino functional group and also increasing the value of n_O/n_N in the formula of these compounds can enhance their density. The correlation is derived on the basis of experimental density values of 100 azole‐based energetic compounds with different molecular structure as training set. The determination coefficient of the new correlation is 0.923. Also, it has the root mean square deviation (RMSD) and the average absolute deviation (AAD) of 0.038 and 0.030 g · cm^–3, respectively. In addition, the correlation gives good predictions for further 25 azole‐based energetic compounds as test set (Q²_EXT = 0.901). The predictive ability of the correlation is checked using a cross validation method (Q²_LMO = 0.918). The proposed method can also apply for designing novel azole‐based energetic compounds.