Non-isothermal thermogravimetric pyrolysis kinetics of waste petroleum refinery sludge by isoconversional approach

Pyrolysis of petroleum refinery sludge has received global acclamation as a clean conversion technique for providing solution of sludge disposal as well as efficient resource utilization. This communication reports the kinetics study of pyrolysis of petroleum refinery sludge. Experiments were carried out by means of thermogravimetric analysis at different heating rates of 5, 10 and 20°C min⁻¹. The pyrolytic reaction is significant in the temperature range of 200–350°C and analysis and evaluation of kinetic parameters is done in the 100–500°C region of non-isothermal TG curves obtained in nitrogen atmosphere. The activation energy is calculated by iso-conversional method, then other kinetic parameters are determined by considering single reaction and two reaction global kinetic model. Two-reaction model is found to fit satisfactorily the experimental results.     

Ammonium Sulphate—Magnesium Promoted Selective Reduction of Aromatic Nitro Compounds

Various nitroarenes and 2,1,3-benznooxadiazole-1-oxides were selectively and rapidly reduces to their corresponding amino and diamino compounds respectively in high yields using (NH₄SO₄-Mg/A1/Bi, a new reduction system.     

Half-Metallic Ferromagnetism in the Co-Doped CdS Diluted Magnetic Semiconductor

JETP Letters - The magnetic properties of Co-doped CdS has been investigated by ab initio calculations using the GGA + U approximation. The study reveals the ferromagnetic ordering of Co-doped CdS...     

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

HZSM‐5‐supported Brönsted and Lewis acidic ionic solid 1,3‐disulfoimidazolium chlorozincate materials ([dsim]₂[ZnCl₄]@HZSM‐5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt‐loaded HZSM‐5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X‐ray diffraction and inductively coupled plasma optical emission spectrometric techniques.     

Synthesis of Functionalized Dihydrofurocoumarin Derivatives from 3-Aminoalkyl-4-hydroxycoumarin

Some dihydrofuro-fused coumarin derivatives were synthesized from 3-aminoalkyl-4-hydroxycoumarin via in situ generation of N-ylide. The 3-aminoalkylated 4-hydroxycoumarin derivatives were synthesized from one-pot, three-component reaction of 4-hydroxycoumarin, aryl aldehydes, and secondary amines in ethanol at room temperature. Again, when salicylaldehyde was employed instead of benzaldehyde, interestingly pyranocoumarins were obtained. The reaction protocol can be further explored toward the synthesis of many other heterocyclic fused dihydrofurans.     

An efficient and regioselective one-pot multi-component synthesis of pyrimido[4,5-d]pyrimidine derivatives in water

Pyrimido[4,5-d]pyrimidine derivatives 4 have been prepared in an efficient and regioselective manner in water via multi-component reaction of isothiocyanate 1, aromatic aldehyde 2, N,N-dimethyl-6-amino uracil 3 in the presence of p-toluenesulfonic acid (p-TSA) as a Lewis acid catalyst.     

A facile microwave assisted synthesis of spiro-1,3-oxazines from N-(2-(cyclohex-1-en-1-yl)ethyl)amides

A mild and efficient methodology has been developed for the synthesis of spiro-1,3-oxazine derivatives by the microwave assisted cyclization of N-2-(1′-cyclohexenyl)ethyl-acetamides/benzamides. The reaction was catalyzed by in situ generated trimethylsilyl iodide and featured by its very short reaction time. The starting materials were easily obtained by the condensation of substituted acetic/benzoic acids with 2-(1′-cyclohexenyl)ethyl amine.     

A Facile Method for Detection and Speciation of Inorganic Selenium with Ion Chromatography

Chromatographia - In this work, we present a new method for the determination and speciation of selenium in water with ion chromatography (IC) using a conductometric detector. Chromatographic...     

Nonparaxial effects on the propagation and scattering of a polarized optical pulse

Propagation characteristics of a polarized optical solitary pulse are analyzed by taking into account the effect of nonparaxiality and mutual interaction. To start with, a pair of generalized nonlinear Schrodinger equations is deduced through an operator approach. Stationary solutions of such a system are then analyzed numerically through a boundary value problem in two stages, with and without the nonparaxial effect. In the second stage, the propagating form of the corresponding spatial soliton is studied by an extended split step algorithm ETDRK. The initial profile is considered to be both a one- and two-soliton solution, to visualize the event of scattering and fusion. From this data, we have computed the intensity, root mean square spectral width, and chirp of a single soliton as it propagates. In the case of the two-soliton solution, we observe that for source parameter values, the fusion is more favored than scattering. It is observed that nonparaxiality and the interaction between A(x) and A(y) tends to destroy the periodic behaviors of these parameters. Lastly, we have investigated the modulational instability of the system as function of frequency detuning and nonparaxiality. The form of the gain is discussed as a function of nonparaxiality.     

Imparting Multifunctionality by Utilizing Biporosity in a Zirconium‐Based Metal–Organic Framework

In this work, we have synthesized nanocomposites made up of a metal–organic framework (MOF) and conducting polymers by polymerization of specialty monomers such as pyrrole (Py) and 3,4‐ethylenedioxythiophene (EDOT) in the voids of a stable and biporous Zr‐based MOF ( UiO‐66 ). FTIR and Raman data confirmed the presence of polypyrrole ( PPy ) and poly3,4‐ethylenedioxythiophene ( PEDOT ) in UiO‐66‐PPy and UiO‐66‐PEDOT nanocomposites, respectively, and PXRD data revealed successful retention of the structure of the MOF. HRTEM images showed successful incorporation of polymer fibers inside the voids of the framework. Owing to the intrinsic biporosity of UiO‐66 , polymer chains were observed to selectively occupy only one of the voids. This resulted in a remarkable enhancement (million‐fold) of the electrical conductivity while the nanocomposites retain 60–70 % of the porosity of the original MOF. These semiconducting yet significantly porous MOF nanocomposite systems exhibited ultralow thermal conductivity. Enhanced electrical conductivity with lowered thermal conductivity could qualify such MOF nanocomposites for thermoelectric applications.