Spinel cobalt manganese oxide nano-composites grown hydrothermally on nanosheets for enhanced photocatalytic mineralization of Acid Black 1 textile dye: XRD,FTIR, FESEM,EDS and TOC studies

Spinel cobalt manganese oxide nano-composites were grown on nanosheets using acetate precursors in mono-ethylene glycol. Crystal structures and morphologies of nano-composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy and energy dispersive X-ray spectroscopy to characterize the element composition. Fourier transform infrared spectroscopy was used for structural characterization and UV–Vis diffuse reflectance spectra (UV–Vis DRS) for optical properties. XRD results showed tetragonal spinel cobalt manganese oxide (Co,Mn)(Co,Mn)₂O₄ and cubic spinel cobalt manganese oxide MnCo₂O_4.5 structural phases. The crystallite size calculated by the Scherrer’s equation was 17 nm. The morphological studies displayed the existence of 40–63 nm nano-powders grown on nanosheets with a good degree of crystallization. Optical properties of cobalt manganese oxide nano-composites exhibit absorbance edge, and the band gap calculated from UV–Vis DRS results was 1.78 eV. FTIR spectra indicated that hydroxyl and oxide groups were major active sites. The absorption bands observed at 656 and 568 cm^?1 are related to stretching vibrations of Mn–O and Co–O, respectively. The photocatalytic activities of nano-composites for photocatalytic mineralization of Acid Black 1 textile dye showed an outstanding performance. Photocatalytic process yielded 91% total organic carbon removals within 2.5 h of irradiation. The enhanced photocatalytic activity was attributed to better charge separation of the photo-generated electron–hole pairs in nano-composite.     

Efficient and Mild Synthesis of Novel Schiff Bases Via One-Pot,Three-Component Reaction Under Solvent-Free Conditions

A simple, efficient, and cost-effective method has been developed for the synthesis of N,N′-bis(2-hydroxybenzylidene)-1,1-diaminoalkanes through one-pot, three-component reaction of salicylaldehyde, aliphatic aldehydes, and ammonium nitrate in the presence of a base under solvent-free conditions at room temperature.     

Nonisothermal crystallization kinetics and determination of surface‐folding free energy of PP/EVA/OMMT nanocomposites

Crystalline structures, nonisothermal crystallization behavior and surface folding free energy of polypropylene (PP)/poly(ethylene‐co‐vinyl acetate) (EVA) blend‐based organically modified montmorillonite (OMMT) nanocomposites were investigated by use of wide angle X‐ray scattering (WAXS) and differential scanning calorimetry (DSC) techniques. Nonisothermal crystallization kinetic analysis was performed using Avrami equation modified by Jeziorny as well as combined Avrami‐Ozawa method. Surface folding free energy and activation energy for PP and nanocomposite samples were also determined employing Hoffman‐Lauritzen's and Vyazovkins's approaches, respectively. The results obtained from transmission electron microscopy (TEM) showed that presence of EVA, which attracts most of the layered silicates, reduces number density of heterogeneous nuclei in the matrix and as a consequence, decreases the nucleation rate. Incorporation of EVA, PP‐g‐MA and OMMT results in a decrease of the chain surface folding free energy level. It was shown that although, OMMT acts as a barrier against the PP macromolecular motion but interestingly, it increases the overall crystallization rate. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 674–684, 2009     

Copper(I)‐N2S2‐salen type complex covalently anchored onto MCM‐41 silica: an efficient and reusable catalyst for the A3‐coupling reaction toward propargylamines

The immobilization of copper complexes by covalent anchoring of the ligand on the surface of mesoporous MCM‐41 has been described. Bis[2‐(phenylthio)benzylidene]‐1,2‐ethylenediamine as a new N₂S₂ donor salen‐type ligand was covalently anchored onto nanopores of MCM‐41 coordinated with copper (I) halide. The organic–inorganic hybrid material was achieved readily using 3‐mercaptopropyltrimethoxysilane as a reactive surface modifier. 2‐Nitrobenzaldehyde was reacted smoothly with the thiol moieties in order to form functionalized nanoporous silica with carbaldehyde groups. The resulting supported organic moieties were converted to thiosalen ligand and coordinated with CuX (X = CN, Cl, Br, I). Characterization of the heterogeneous catalyst by X‐ray diffraction, N₂ sorption, FT‐IR, diffuse reflectance UV‐visible and TGA techniques indicated successful grafting of the copper complex inside the nano‐channels of MCM‐41. The heterogenized catalyst was evaluated by the Mannich condensation reaction of aldehydes, amines and alkynes. In this reaction, the corresponding propargylamines were obtained as single products in good to excellent yields. Factors such as reaction temperature, solvent, catalyst loading, leaching and reusability of the catalyst also were discussed. The use of MCM‐41 as support permits an easier separation and recycles with only a marginal decrease in reactivity. Copyright © 2013 John Wiley & Sons, Ltd.     

SnCl2/nano SiO2：A green and reusable heterogeneous catalyst for the synthesis of polyfunctionalized 4H-pyrans

A highly efficient and general method for the synthesis of polyfunctionalized 4H-pyrans is established through a one-pot multicomponent cyclocondensation of aromatic aldehydes with CH acids, malononitrile and ethyl acetoacetate using nano silica supported tin (Ⅱ) chloride as a catalyst. In this method SnCl2/nano SiO2 was used as green and reusable catalyst. Excellent yields, short reaction times, simple workup, and inexpensiveness and commercially availability of the catalyst are the advantages of this method.     

Determination of RDX and Keto-RDX in High-Explosive Mixtures by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - High-performance thin-layer chromatography (HPTLC) has been used for separation and quantitation of components of high explosives...