Vanadate

About: Vanadate is a research topic. Over the lifetime, 4497 publications have been published within this topic receiving 120109 citations. The topic is also known as: vanadate.

Size controllable synthesis of cobalt vanadate nanostructures with enhanced photocatalytic activity for the degradation of organic dyes

Abstract: Different types of cobalt vanadate nanostructures such as Co3V2O8, Co2V2O7 and CoV2O6 have been successfully prepared via a simple solid-state method. For the first time, cobalt vanadate nanostructures were synthesized via Schiff-base ligand and vanadyl sulfate as a capping agent and vanadium source, respectively. The effect of a Schiff-base ligand (N,N-Bis (salicylaldehyde) ethylenediamine = H2salen) as a capping agent, molar ratio of Co: H2salen and Co:V on type of products, morphology and size of cobalt vanadate nanoparticles was investigated to reach optimum condition. The as-prepared nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), Fourier transform infrared (FT-IR) spectra, energy dispersive X-ray microanalysis (EDX) and ultraviolet–visible (UV–vis) spectroscopy. This work is the first study on photocatalytic activity of cobalt vanadate nanostructures in different conditions. The influence of different parameters such as type of cobalt vanadate nanostructures, type of dye, size of particles and nanostructures dosage as a catalyst on photocatalytic activity of samples were studied.

Positive inotropism of vanadate in cat papillary muscle.

Abstract: MANY samples hf ‘Sigma grade’ ATP from Sigma Chemical Co. reportedly contained an impurity which induces anomalous kinetics of (Na, K)-ATPase activity1–3. This impurity has recently been identified as vanadate4, and shown to inhibit (Na, K)–ATPase from kidney4 and red blood cells5. These findings have received considerable interest because of a possible physiological role of vanadate as an endogenous regulator of (Na, K)–ATPase activity3–5. We now report that vanadate is capable of producing positive inotropic effects in electrically driven papillary muscles isolated from cats.

Isolation of ATPase I, the proton pump of chromaffin-granule membranes.

Abstract: Chromaffin-granule membranes contain two ATPases, which can be separated by (NH4)2SO4 fractionation after solubilization with detergents, or by phase segregation in Triton X-114. ATPase I (Mr 400000) is inhibited by trialkyltin, quercetin and alkylating agents, and hydrolyses both ATP and ITP. It contains up to five types of subunit, including a low-Mr hydrophobic polypeptide that reacts with dicyclohexylcarbodi-imide; these subunits are unrelated to those of mitochondrial F1F0-ATPase, as judged by size and reaction with antibodies. ATPase II (Mr 140000) is inhibited by vanadate, and is specific for ATP; it has not been extensively purified. Proton translocation by resealed chromaffin-granule 'ghosts', measured by uptake of methylamine or by quenching of the fluorescence of 9-amino-6-chloro-2-methoxyacridine, is supported by the hydrolysis of ATP or ITP, and inhibited by quercetin or alkylating agents, but not by vanadate. ATPase I must therefore be the proton translocator involved in the uptake of catecholamines and possibly of other components of the chromaffin-granule matrix, whereas ATPase II does not translocate protons.

Corrosion Inhibition of Aluminum Alloy 2024-T3 by Aqueous Vanadium Species

Abstract: Nuclear magnetic resonance NMR measurements were made on aqueous vanadate solutions to characterize speciation as a function of pH and vanadate concentration. Additionally, potentiodynamic polarization measurements were carried out on Al alloy 2024-T3 in 50 mM NaCl solutions in which pH and vanadate concentration were systematically varied. Results showed that inhibition by vanadates occurred mainly in alkaline solutions where tetrahedrally coordinated vanadates, metavanadate and pyrovanadate, were abundant. Inhibition was not observed in solutions where octahedrally coordinated decavanadates predominated. Anodic inhibition, in the form of increased pitting potential, was observed in both aerated and deaerated solutions. In contrast, cathodic inhibition was observed only in aerated solutions acting primarily through the suppression of oxygen reduction. Energydispersive spectroscopy, used to collect chemical maps from aluminum coupons exposed to vanadate solutions, showed the suppression of Al2CuMg particle dissolution compared to vanadate-free solutions. NMR measurements were also used to track changes in vanadate speciation with time, pH adjustment, and with exposure to metallic aluminum surfaces. NMR showed noninhibiting octahedrally coordinated decavanadates rapidly decompose into inhibiting tetrahedrally coordinated metavanadates and pyrovanadates after alkaline pH adjustment. While decomposition begins immediately upon pH adjustment, equilibrium may not be reached even after significant time periods. © 2008 The Electrochemical Society. DOI: 10.1149/1.2907772 All rights reserved.