Emulsion liquid membrane extraction of zinc by a hollow-fiber contactor

Emulsion liquid membranes (ELMs) can contribute to process intensification of zinc extraction, by significantly reducing the solvent and carrier requirements in comparison with conventional solvent extraction. Di(2-ethylhexyl)phosphoric acid (D2EHPA) was used as a highly selective carrier for the transport of zinc ions through the emulsified liquid membrane. The hollow-fiber extractor appears to offer significant advantages over conventional liquid–liquid contactors for this separation because emulsion leakage and swell are practically eliminated even when treating high concentration feeds. Various hydrodynamic and chemical parameters, such as variation in feed pH; zinc concentration in feed; variation in concentrations of D2EHPA; variation in feed/emulsion volume ratios and variation in feed and emulsion flow rates, were investigated. The content of sulfuric acid as an internal did not show in the studied range any significant influence on zinc extraction through the ELM, although a minimum hydrogen ion concentration is suggested in the internal aqueous solution to ensure acidity gradient between both aqueous phases to promote the permeation of zinc ions toward the internal phase. The experimental mass-transfer coefficients have shown a stronger dependence on hydrodynamic conditions in both the external feed phase and emulsion among the parameters studied. For emulsion flow rate, mass-transfer coefficient increased from 16.3 × 10⁻⁶ m/s at 200 ml/min to 31.2 × 10⁻⁶ m/s at 640 ml/min. Significant increasing in mass-transfer coefficient observed with increasing aqueous flow rate from 9.7 × 10⁻⁶ m/s at 170 ml/min to 37.2 × 10⁻⁶ m/s at 740 ml/min. The overall mass-transfer coefficient increases from 12 × 10⁻⁶ m/s at 2% D2EHPA to 28 × 10⁻⁶ m/s at 8% D2EHPA. This means that this process is chemically controlled and the interfacial resistance has a more significant role in the extraction of zinc by emulsion liquid membrane through hollow-fiber contactor. From the results obtained, it seems that the diffusion processes in aqueous feed phase and the membrane phase have the same importance as the chemical process.     

Extended structure design with simple molybdenum oxide building blocks and urea as a directing agent

We report here a simple one-pot directed synthesis of an oxomolybdate urea composite in which elementary molybdenum oxide building blocks are linked together with the aid of urea. This type of directed material design resulted in large rod-like crystals of an inorganic-organic hybrid extended structure of {MoO 3(NH 2-CO-NH 2)} infinity consisting of right- and left-handed helical units. In the crystal structure urea acts both as a glue that links the inorganic molybdenum units into a helix and as a supramolecular linker for the stabilization of the crystal structure as a whole. This type of molecular topology resulted in an unexpectedly high thermal stability.     

Xeniaphyllane-derived terpenoids from the formosan soft coral Sinularia gibberosa

New xeniaphyllane-derived metabolites (1-7) were isolated from the EtOAc extract of the Formosan soft coral Sinularia gibberosa. The structures and relative configurations of these compounds were elucidated on the basis of extensive spectroscopic analysis (including 2D NMR) and by comparison of their spectral data with those of related compounds. In vitro cytotoxic evaluation of the above metabolites towards a limited panel of cancer cell lines is also described.     

A novel color removal adsorbent from heterocoagulation of cationic and anionic clays

We report the preparation and characterization of a novel nanocomposite adsorbent for anionic dye removal. The nanocomposite adsorbent was prepared by heterocoagulation of delaminated bentonite and layered double hydroxide (LDH) colloids. The effects of preparation conditions, LDH loading, particle size, and calcination temperature of the modified material on the physicochemical properties of this composite adsorbent have been investigated. The optimal conditions for best Reactive Yellow 2 (RY2) dye removal efficiency are a weight ratio of LDH to bentonite of 1:1, LDH particle size 100 nm, and calcination temperature 673 K. The adsorption equilibrium data can be fitted well by the widely accepted adsorption isotherm models.     

New one step synthesis of 3,5‐disubstituted 1,2,4‐oxadiazoles

Disubstituted 1,2,4‐oxadiazoles have been synthesized in good yields and good purity in one pot procedure by reaction of aromatic nitriles, hydroxylamine hydrochloride and sodium carbonate in ethylene glycol under heating at 195°C. The structures of different 1,2,4‐oxadiazoles obtained were confirmed by ¹H, ¹³C NMR and mass spectroscopy.     

The Use of Megamolecular Polysaccharide Sacran in Food and Biomedical Applications

Natural polymer is a frequently used polymer in various food applications and pharmaceutical formulations due to its benefits and its biocompatibility compared to synthetic polymers. One of the natural polymer groups (i.e., polysaccharide) does not only function as an additive in pharmaceutical preparations, but also as an active ingredient with pharmacological effects. In addition, several natural polymers offer potential distinct applications in gene delivery and genetic engineering. However, some of these polymers have drawbacks, such as their lack of water retention and elasticity. Sacran, one of the high-molecular-weight natural polysaccharides (megamolecular polysaccharides) derived from Aphanothece sacrum (A. sacrum), has good water retention and elasticity. Historically, sacran has been used as a dietary food. Moreover, sacran can be applied in biomedical fields as an active material, excipient, and genetic engineering material. This article discusses the characteristics, extraction, isolation procedures, and the use of sacran in food and biomedical applications.     

Chemistry of Phosphorus Ylides. Part 40. Synthesis of Pyrazoles by the [3 + 2] Cycloaddition of Diazo Compounds with Wittig Reagents as Antimicrobial Compounds

A comparative study between the reactions of active phosphacumulenes and stabilized phosphonium ylides on some diazo compounds have been performed. A number of substituted phosphanylidene spiro pyrazoles have been synthesized from the reaction of the active phosphacumulenes and the diazo derivatives. On the other hand, treatment of the diazo substrates with the stabilized phosphonium ylides led to the formation of the corresponding ylidenes and diazenyl phosphanylidenes. The antimicrobial activities for the new compounds are also reported.     

Electrochemical Stability of the Reconstructed Fe3O4(001) Surface

Establishing the atomic-scale structure of metal-oxide surfaces during electrochemical reactions is a key step to modeling this important class of electrocatalysts. Here, we demonstrate that the characteristic (√2×√2)R45° surface reconstruction formed on (001)-oriented magnetite single crystals is maintained after immersion in 0.1 M NaOH at 0.20 V vs. Ag/AgCl and we investigate its dependence on the electrode potential. We follow the evolution of the surface using in situ and operando surface X-ray diffraction from the onset of hydrogen evolution, to potentials deep in the oxygen evolution reaction (OER) regime. The reconstruction remains stable for hours between −0.20 and 0.60 V and, surprisingly, is still present at anodic current densities of up to 10 mA cm⁻² and strongly affects the OER kinetics. We attribute this to a stabilization of the Fe₃O₄ bulk by the reconstructed surface. At more negative potentials, a gradual and largely irreversible lifting of the reconstruction is observed due to the onset of oxide reduction.     

Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex

A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.