Selective homogeneous liquid-liquid extraction and preconcentration of copper(II) into a micro droplet using a benzo-substituted macrocyclic diamide, and its determination by electrothermal atomic absorption spectrometry

A fast and reliable method was developed for the selective separation and preconcentration of Cu²⁺ ions using homogeneous liquid-liquid extraction using a novel benzo-substituted macrocyclic diamide, 5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioatriazacyclo-pentadecine-3,11(4 H,12 H)-dione, as a selective complexing agent. An aqueous solution of Zonyl FSA (FSA) was used as a phase-separation agent at pH 4.5. Electrothermal atomic absorption spectrometry was used for Cu²⁺ determination after preconcentration. The influences of pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the ligand and the effect of diverse ions were investigated. Factorial design and response surface methods were used for the optimization purposes. Under the optimum experimental conditions, 50 ng of Cu²⁺ in 5 mL aqueous sample could be extracted quantitatively into 76 µL of the sediment phase. The maximum preconcentration factor was 65. The calibration curve was linear in the concentration range 0.2 to 4.0 µg L^?1. The detection limit and relative standard deviation were 4 ng L^?1 and 4.6%, respectively. The method was successfully applied to the extraction and determination of Cu²⁺ in natural water samples.     

Applying the Principles of Green Chemistry to Polymer Production Technology

The 12 principles of green chemistry are reviewed and applied specifically to polymer production. Examples of how the principles relate to current practice in polymer reaction engineering and which areas show the greatest potential impact for implementation of these principles are discussed. This paper does not attempt to be exhaustive but rather to target specific areas for further development.     

基于1,3-二吗啉基丙烷的Hg(Ⅱ)和Zn(Ⅱ)配合物:合成、结构与抗菌活性

以1,3-二吗啉基丙烷(DMP)为配体合成了2个配合物：Hg(DMP)Cl₂(1)和Zn(DMP)Cl₂(2),并对其结构进行了表征。单晶X-射线结构分析表明,2个配合物中的金属离子都与2个N原子和2个Cl原子配位,形成扭曲四面体配位结构。配体和配合物对3种革兰氏阳性菌(S. aureus ATCC 25923,E. faecalis ATCC 23212和S. epidermidis ATCC 34384)和3种革兰氏阴性菌(E. coli ATCC 25922,P. aeruginosa ATCC 27853和K. pneumonia ATCC 70063)都具有抗菌活性,且在一定条件下,Hg(Ⅱ)配合物的抗菌活性超过了作为标准的磺胺异恶唑药物。     

Fe3O4@S‐ABENZ@VO: Magnetically separable nanocatalyst for the efficient,selective and mild oxidation of sulfides and oxidative coupling of thiols

Oxovanadium(IV) immobilized on Fe₃O₄@S‐ABEN is reported as a highly efficient nanocatalyst for the oxidation of sulfides and oxidative coupling of thiols (using H₂O₂ as green oxidant), the products of which are obtained in high to excellent yields. The products can be separated by a simple extraction with organic solvent and the catalyst is highly efficient, especially in terms of selectivity of desired product. The catalytic system can be recycled and reused without significant loss of catalytic activity.     

Modeling the effects of type and concentration of organic modifiers, column type and chemical structure of analytes on the retention in reversed phase liquid chromatography using a single model

A previously proposed model for representing the retention factor (k) of an analyte in mixed solvent mobile phases was extended to calculate the k of different analytes with respect to the nature of analyte, organic modifier, its concentration and type of the stationary phase. The accuracy of the proposed method was evaluated by calculating mean percentage deviation (MPD) as accuracy criterion. The predicted vs. observed plots were also provided as goodness of fit criteria. The developed model prediction capability compared with a number of previous models (i.e. LSER, general LSER and Oscik equation) through MPD and fitting plots. The proposed method provided acceptable predictions with the advantage of modeling the effects of organic modifiers, mobile phase compositions, columns and analytes using a single equation. The accuracy of developed model was checked using the one column and one analyte out cross validation analyses and the results showed that the developed model was able to predict the unknown analyte retention and the analytes retentions on unknown column accurately.     

Nonlinear responses and optical limiting behavior of fast green FCF dye under a low power CW He-Ne laser irradiation

The nonlinear responses and optical limiting performance of a dye type acid, called fast green FCF, are investigated under irradiation of 35 mW continuous wave He-Ne Laser. The second order refractive index and nonlinear absorption coefficient are measured by use of z-Scan technique. The optical limiting behavior is investigated by transmission measurement through the sample. Linear absorption coefficient (α), nonlinear absorption coefficient (β) and second order refractive index (n₂) of fast green FCF are measured at different concentrations.     

An Efficient Catalytic Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Citric Acid/Al(NO3)3.9H2O/MBr Under Mild and Heterogeneous Conditions

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using Al(NO₃)₃.9H₂O, citric acid and a catalytic amount of KBr or NaBr in the presence of wet SiO₂ (50% w/w)in CH₂Cl₂ under mild and heterogeneous conditions in good to high yields.     

Gas permeation properties of ethylene vinyl acetate–silica nanocomposite membranes

The effect of silica nanoparticles on the gas separation properties of ethylene vinyl acetate (EVA) copolymer containing 28% vinyl acetate has been investigated. The EVA and hybrid EVA–silica membranes were prepared via thermal phase inversion method. Silica nanoparticles prepared by hydrolysis of tetraethylorthosilicate (TEOS), through the sol–gel mechanism. The prepared membranes were characterized using FT-IR, SEM, DSC and XRD methods. FT-IR and SEM results indicated the nanoscale dispersion of silica particles in polymer matrix. As confirmed by XRD and DSC analyses, increasing the silica content enhances the amorphous regions significantly. Gas permeation of EVA–silica nanocomposite membranes with silica contents of 5, 6 and 10 wt.% was studied for N₂, O₂, CO₂ and CH₄ single gases at pressures of 4, 6 and 8 bar. The obtained results suggest a significant increase in permeability of all gases and an increase in CO₂/N₂ and CO₂/CH₄ gases selectivities upon increasing the silica content. The possible reasons for such behavior were stated and discussed. The pressure dependence of the gas permeabilities of the membranes was also investigated.