Kinetics of malachite green fading in alcohol–water binary mixtures

The rate constant of alkaline fading of malachite green (MG⁺) was studied in alcohol–water binary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283–303 K. It was observed that the reaction rate constants were increased in the presence of different weight percentages of methanol, ethanol, 1‐propanol, 2‐propanol, ethylene glycol, 1,2‐propanediol, and glycerol (up to 19.3%). In aqueous glycerol solutions higher than 19.3%, the rate constant of reaction slightly decreases, which is due to high viscosity values of solvent mixtures. The fundamental rate constants of MG⁺ fading in these solutions were obtained by using the SESMORTAC model. Owing to the charged character of activated complex, with an increase in the weight percentage of the used cosolvents or temperature, k₂ values change according to the trend of hydroxide ion nucleophilic parameter values. Also, using MG⁺ solvatochromism, a simple test, called MAGUS, is introduced for measuring the glycerol concentration in its aqueous solutions. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 508–518, 2010     

Fracture Behavior of Covalently Re-Modified MWNT/Epoxy Nanocomposites

Summary: In this work, a surface re-modified multi-walled carbon nanotube (MWNT) was prepared by the chemical attachment of oligomeric unsaturated polyester on the MWNT surface. The re-modified MWNT was incorporated in two concentrations of 0.35 and 0.70 Wt.% into epoxy resin in order to investigate its effect on morphology and mechanical behavior of the MWNT/epoxy nanocomposite. The transmission electron microscopy showed that the re-modification of MWNT surface improves its dispersion state in the epoxy matrix. The tensile measurements for the nanocomposite having different amounts of surface re-modified/not-modified MWNT showed that the fracture mechanism changed from brittle to tough beyond a certain amount of surface re-modified MWNT. The scanning electron microscopy findings on the fracture surface morphology of the resulted nanocomposite substantiated the observed phenomena.     

Intensification of gadolinium(III) separation by effective utilization of nanoliquids in supported liquid membrane using Aliquat 336 as carrier

A supported nanoliquid membrane was developed to improve the separation of rare metal ion gadolinium (Gd) from nitrate solution medium. The nanoliquid membrane was prepared by dispersion of nanoparticles in organic phase and Aliquat 336 was applied as the carrier. TiO₂ and SiO₂ as hydrophobic and hydrophilic nanoparticles were effectively incorporated in the supported liquid membrane (SLM) system and the effect of size, concentration, and type of nanoparticle in the SLM were evaluated. A membrane phase of 0.015 M Aliquat-336 in kerosene and 0.04 wt% of SiO₂ with the size of 15 nm was found to have the highest permeability coefficient of 12.57?×?10^?5 m/s and enhanced the permeability coefficient by 28.2%. Hydrophobicity and hydrophilicity of the nanoparticles were observed to have remarkable effects on the permeation of the SLM system and concluded that the hydrophobic nanoparticle was more desirable. Results showed that the solid supported pore’s blockage and aggregation of nanoparticles could bring adverse effects at a high nanoparticle concentration at this SLM configuration. The stability tests were conducted over ten cycles of separation and the supported nanoliquid membrane had slight reduction of permeation during the test.     

Synthesis of benzodiazepines catalyzed by chitosan functionalized by triacid imide as a superior catalyst

Research on Chemical Intermediates - Chitosan functionalized by triacid imide has been applied as an effective catalyst for the synthesis of benzodiazepines by one-pot reactions of...     

Experimental Study of the Influence of Different Load Changes in Inlet Gas and Solvent Flow Rate on CO2 Absorption in a Sieve Tray Column

An experimental study was conducted in a sieve tray column. This study used a simulated flue gas consisting of 30% CO₂ and 70%. A 10% mass fraction of methyl diethanolamine (MDEA) aqueous solution was used as a solvent. Three ramp-up tests were performed to investigate the effect of different load changes in inlet gas and solvent flow rate on CO₂ absorption. The rate of change in gas flow rate was 0.1 Nm³/h/s, and the rate of change in MDEA aqueous solution was about 0.7 NL/h/s. It was found that different load changes in inlet gas and solvent flow rate significantly affect the CO₂ volume fraction at the outlet during the transient state. The CO₂ volume fraction reaches a peak value during the transient state. The effect of different load changes in inlet gas and solvent flow rate on the hydrodynamic properties of the sieve tray were also investigated. The authors studied the correlation between the performance of the absorber column for CO₂ capture during the transient state and the hydrodynamic properties of the sieve tray. In addition, this paper presents an experimental investigation of the bubble-liquid interaction as a contributor to entropy generation on a sieve tray in the absorption column used for CO₂ absorption during the transient state of different load changes.     

Preparation of Polycarbonate-ZnO Nanocomposite Films: Surface Investigation after UV Irradiation

Polycarbonate (PC)-ZnO films with different percentages of ZnO were prepared by a solution stirring technique and subjected to ultraviolet (UV; λ = 254 nm) irradiation. Structural parameters of the samples and the effects of UV irradiation on the surface properties of the PC and PC-ZnO nanocomposites were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), water contact angle (WCA) measurements, and a Vickers microhardness (H_V) tester. The XRD patterns of the nanocomposite films were found to show an increase in crystallinity with the increasing ZnO nanoparticles percentage. The WCA was found to be reduced from 90° to 17° after 15 h of UV irradiation, which could be ascribed to the oxidation of the surface of the samples during the irradiation and exposure of the ZnO nanoparticles, a result that is also supported by the obtained XPS data. The microhardness value of the PC-ZnO films including 30 wt.% ZnO enhanced considerably after UV radiation, which can also be attributed to the exposition of the ZnO nanoparticles after photodegradation of the PC superficial layer of the nanocomposite films.     

Synthesis and spatial structure of new chiral dopants from allobetuline series for cholesteric liquid-crystal compositions

Structural Chemistry - New series of chiral dopants for cholesteric liquid-crystal compositions were synthesized on the base of 2-substituted allobetuline derivatives, and their steric structure...     

A note on infinite aS-groups

Let G be a group. If every nontrivial subgroup of G has a proper supplement, then G is called an aS-group. We study some properties of aS-groups. For instance, it is shown that a nilpotent group G is an aS-group if and only if G is a subdirect product of cyclic groups of prime orders. We prove that if G is an aS-group which satisfies the descending chain condition on subgroups, then G is finite. Among other results, we characterize all abelian groups for which every nontrivial quotient group is an aS-group. Finally, it is shown that if G is an aS-group and |G| ≠ pq, p, where p and q are primes, then G has a triple factorization.     

Pyridine-2,6-Dicarboxylic Acid (Dipic): Crystal Structure from Co-Crystal to a Mixed Ligand Nickel(II) Complex

Abstract  

Pyridine-2,6-dicarboxylic acid (dipic) was used for the synthesis of a co-crystal with 1,10-phenanthroline-5,6-dione (phen-dione) and a nickel(II) complex. The co-crystal dipic·phen-dione·4H₂O (1) has been synthesized and studied by X-ray crystallography. The structure is stabilized with hydrogen bonds between dipic, H₂O and phen-dione. It is surprising that there is no direct hydrogen bonding between phen-dione and dipic and yet the molecules co-crystallize in aqueous solution. A new complex of nickel(II), [Ni(phen)(dipic)(H₂O)]·4H₂O (2), (where phen = 1,10-phenanthroline) has been synthesized and characterized by elemental and thermogravimetric analyses, FT-IR, UV–Vis and ¹H-NMR spectroscopy. The structure of (2) has been studied by X-ray crystallography. The coordination around Ni(II) is a distorted octahedron. The crystal packing shows that the dimensionality of (2) is enlarged to 3D, through hydrogen bonds and π–π interactions. Cyclic voltammetry of (2) shows that the Ni(II/I) couple is irreversible.