new forms of vanadium oxide nanoporous were fabricated using a simple chemical synthesis method. vanadium pentoxide (v2o5) nanoporous were synthesized by sodium metavanadate as precursor and ethylene glycol as surfactant. the samples were characterized by high resolution transmission electron microscopy (hrtem), field effect scanning electron microscopy (fesem) and x-ray diffraction (xrd), four...

fossil fuel power plant is one of the most important sources of environmental pollution of the vanadium toxic metal. this survey showed that the penicilium austuranium is the best microorganism for biosorption of vanadium isolated from environment of fossil fuel power plant. to determine the optimum ph and most biosorption and accumulation of vanadium by these fungi, power plants wastewater, pa...

The present results show that indeed the structural data allow us to decide which vanadium centers must be considered formally as + 5 and which as + 4, at least with respect to the limit of strong localization. In fact, if the V3 and V3a centers were to be considered as vanadium(Iv), or as intermediates between vanadium(rv) and vanadium(v), they would be involved in several strong p o x 0 bridg...

The biological image of the transition element vanadium ferments a great deal of contradiction-from toxicity to essentiality. Importance of this element as micro-nutrient is yet to be unequivocally accepted by biologists and biomedical scientists. In spite of toxicity, it seems interesting to analyze the different biological roles of the element. Vanadium compounds have been proven to be associ...

Structurally well-defined bimetallic titanium(IV) (salen) and monometallic vanadium(V) (salen) complexes have been used as catalysts for the asymmetric addition of trimethylsilyl cyanide to β-nitroalkenes to produce chiral nitronitriles with ee values in the range of 79-89 % and conversions up to 100 % at 0 °C. The reaction conditions (solvent, temperature, time and vanadium complex counter-ion...

Single-crystalline V(2)O(5)·xH(2)O nanorings and microloops were chemically assembled via an ion-induced chemical spinning route in the designed hydrothermal system. The morphology and structure of products were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray powder diffraction (XRD) measurement, energy-dispersive X-ray spectroscopy ...

The reactivities of the adamantane-like heteronuclear vanadium-phosphorus oxygen cluster ions [V(x)P(4-x)O(10)](.+) (x=0, 2-4) towards hydrocarbons strongly depend on the V/P ratio of the clusters. Possible mechanisms for the gas-phase reactions of these heteronuclear cations with ethene and ethane have been elucidated by means of DFT-based calculations; homolytic C-H bond activation constitute...

A method is described for the determination by solid phase spectrophotometry (SPS) of trace amounts of vanadium in natural water and crude petroleum samples. The procedure is based on fixation on a dextran-type anion exchanger of the complex V(IV)-Eriochrome Cyanine R. The absorbance of the gel, at 563 and 750 nm, packed in a 1 mm cell, is measured directly. Vanadium can be determined in the 0....

Superlattices have attracted great interest because of their tailorable electronic properties at the interface. However, the lack of an efficient and low-cost synthetic method represents a huge challenge to implement superlattices into practical applications. Herein, we report a space-confined nanoreactor strategy to synthesize flexible freestanding graphene-based superlattice nanosheets, which...

This study describes a new simple, sensitive and selective catalytic kinetic spectrophotometricmethod for the determination of vanadium (V). The method is based upon the catalytic effect ofvanadium (V) on the oxidation of Carminic acid by bromate in sulfuric acid media. The reaction wasfollowed spectrophotometrically by measuring the decrease in absorbance at 490 nm and thedependence of sensiti...