Showing papers on "Sodium metavanadate published in 2019"

Vanadium compounds and cellular death mechanisms in the A549 cell line: The relevance of the compound valence.

Abstract: Non-small lung cell carcinoma has a high morbidity and mortality rates. The elective treatment for stage III and IV is cisplatinum that conveys serious toxic side effects. Vanadium compounds are metal molecules with proven antitumor activity that depends on its valence. Therefore, a better understanding of the mechanism of action of vanadium compounds is required. The aim of our study was to investigate the mechanisms of cell death induced by sodium metavanadate (NaVO3 [V(+5)]) and vanadyl sulfate (VOSO4 [(+4)]), both of which have reported apoptotic-inducing activity. We exposed the A549 cell line to various concentrations (0-100 μM) and to different exposure times to each compound and determined the cell viability and expression of caspases, reactive oxygen species (ROS) production, Bcl2, Bax, FasL and NO. Our results showed that neither compounds modified the basal expression of caspases or pro- and anti-apoptotic proteins. The only change observed was the 12- and 14-fold significant increase in ROS production induced by NaVO3 and VOSO4 , respectively, at 100 μm concentrations after 48 hours. Our results suggest that classical apoptotic mechanisms are not related to the cell death induced by the vanadium compounds evaluated here, and showed that the higher ROS production was induced by the [(+4)] valence compound. It is possible that the difference will be secondary to its higher oxidative status and thus higher ROS production, which leads to higher cell damage. In conclusion, our results suggest that the efficacy of the cell death mechanisms induced by vanadium compounds differ depending on the valence of the compound.

Effect of practical parameters on the structure and corrosion behavior of vanadium/zirconium conversion coating on AA 2024 aluminum alloy

Abstract: In this research corrosion behavior of the hexafluorozirconic acid-based conversion coating (ZrCC) applied on the surface of AA2024 aluminum alloy, in the absence and presence of sodium metavanadate (ZrVCC), has been investigated. At the first step, practical parameters of ZrCC conversion coating were optimized using data of polarization resistance (Rp) and corrosion current density (icorr) obtained from electrochemical impedance spectroscopy and polarization techniques, respectively. In the next step the effect of sodium metavanadate presence by assessment on the effect of parameters including concentration of sodium metavanadate, immersion time, and solution pH on surface and electrochemical properties was investigated. The optimized practical conditions for ZrCC were immersion time of 60 s in 0.01 M of H2ZrF6 solution at room temperature and solution pH = 2. For the ZrVCC sample, the best results appeared for the immersion time of 60 s in the bath containing 1 g/lit sodium metavanadate at room temperature and pH = 2. Corrosion current density value of the ZrVCC sample was 0.07 µA/cm2 which seems to be 10 times smaller than its amount for the uncoated sample. Film formation of conversion coatings was investigated by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM). FE-SEM and EDS test results revealed that zirconium compounds mostly precipitated on the surface of intermetallic particles.

Rare Earth-Based Compounds as Inhibitors of Hot-Corrosion Induced by Vanadium Salts

Abstract: In this study, the performance evaluation of lanthanum compounds as corrosion inhibitors of vanadium salts was performed. The inhibitors tested were lanthanum acetate and La2O3. The performance of the inhibitors was tested using sodium metavanadate (NaVO3) as a corrosive medium at 700, 800, and 900 °C. The corrosion inhibitory effect was evaluated on the corrosion process of 304H stainless steel. The corrosion rate of the steel was determined by the mass loss technique after 100 h of immersion in the corrosive salt with and without the addition of the corrosion inhibitor. The results show that lanthanum compounds act as corrosion inhibitors of vanadium salts. The inhibitory effect increases by increasing the concentration and tends to decrease when increasing the test temperature. Lanthanum compounds act as excellent corrosion inhibitors due to their ability to stabilize vanadium cations. Vanadium is stabilized by forming a new compound, lanthanum vanadate (LaVO4), with a melting point much higher than the compounds formed when Mg or Ni compounds are used as corrosion inhibitors.

Preparation method of cuprous sulfide/vanadium trioxide serving as full PH electrocatalyst

Abstract: Disclosed is a preparation method of cuprous sulfide/vanadium trioxide serving as a full PH electrocatalyst. The method comprises the steps that copper foam is sequentially immersed in a pure acetonesolution and a hydrochloric acid solution for ultrasonic cleaning, then alternately washed with ethanol and deionized water separately and subjected to vacuum drying to obtain treated copper foam; sodium metavanadate and thioacetamide are dissolved in deionized water to obtain a suspension solution A; the suspension solution A and the copper foam treated in the first step are loaded into a high-pressure reaction kettle and then placed in a reaction oven for a hydrothermal reaction, the reaction kettle is cooled at room temperature, and a product is washed with deionized water and ethanol several times and then subjected to vacuum drying to obtain the cuprous sulfide/vanadium trioxide serving as the full PH electrocatalyst. According to the preparation method, with the sodium metavanadate as a vanadium source and thioacetamide as a sulfur source, Cu2S/V2O3 is successfully synthesized in situ on the copper foam by means of a one-step hydrothermal method. The method is low in cost, shortin reaction cycle, mild in reaction condition, simple in preparation process, stable in product quality, uniform in shape, environmentally friendly and suitable for large-scale production.

Preparation method of self-cleaning fibers

Abstract: The invention provides a preparation method of self-cleaning fibers, and belongs to the field of water purification materials. The preparation method of the self-cleaning fibers comprises the following process steps: mixing deionized water, sodium metavanadate and ethylenediamine tetraacetic acid disodium, regulating pH of a solution with hydrochloric acid, and then adding a mixed solution of deionized water, bismuth nitrate pentahydrate, neodymium nitrate and sodium bicarbonate to prepare an active precursor solution; carrying out hydrothermal reaction on the active precursor solution and aluminium silicate fibers, and drying and calcining to obtain the self-cleaning fibers. The self-cleaning fibers consist of aluminium silicate fibers of which the surfaces are coated with bismuth neodymium vanadate, resist high temperature, are flexible, are high in strength, can float in water, and can degrade organic pollutants in water under the condition of illumination.

Preparation method and application of vanadium tetrasulfide@ carbon nanotube composite powder

Abstract: A preparation method of vanadium tetrasulfide@ carbon nanotube composite powder comprises the following steps: weighing and adding 48-52 mg of carbon nanotubes into 58-62 ml of deionized water for ultrasonic treatment to obtain a uniformly dispersed black solution A; weighing 0.9-1.1 g of sodium metavanadate and 3.5-3.7 g of thioacetamide, simultaneously adding the sodium metavanadate and the thioacetamide into a solution A, and magnetically stirring to obtain a solution B; pouring the solution B into a reaction lining, then sealing, arranging the lining into an outer kettle, fixing the lining, then placing the lining into a homogeneous reaction instrument, and reacting at the temperature of 175-185 DEG C for 23-25 h under the condition that the rotating speed is 5-10 r/min; after the hydrothermal reaction is finished, naturally cooling the reaction kettle to the room temperature, taking out a cooled product after reaction, and collecting the product after the product is alternately cleaned by water and alcohol; placing the collected product in a cold well of a freeze dryer to be frozen, then placing the frozen product in a tray, and covering the tray with a sealing cover, and collecting the product after vacuum drying so as to obtain the vanadium tetrasulfide@ carbon nanotube composite powder. The preparation method of the vanadium tetrasulfide@ carbon nanotube composite powder has the characteristics of simple reaction process, low temperature, easiness in control and no need of large equipment or harsh reaction conditions.

Vanadium-modified Ni3S2 nano-rod array electrode material and preparation method thereof

Abstract: The invention provides a vanadium-modified Ni3S2 nano-rod array electrode material which has a scale-shaped surface appearance formed by self-assembling particles A preparation method comprises the following steps: immersing metal nickel in a suspension solution containing a vanadium source, a sulfur source and ammonium fluoride, and carrying out solvothermal reaction; then, calcining a product of the solvothermal reaction to obtain the nano-rod-shaped vanadium-modified Ni3S2 electrode material The vanadium source is vanadiumoxy acetylacetonate, sodium metavanadate, sodium vanadate, sodium vanadate dodecahydrate, ammonium metavanadate or vanadium pentoxide; the sulfur source is thiourea, thioacetamide, sodium sulfide, sodium oiethyl dithiocarbamate or a sulfur elementary substance A nano-rod structure formed by self-assembling the particles has a secondary-grade unit so that catalytic active sites of the material are effectively increased; compared with a block-shaped catalyst, theresistance of the material is effectively reduced and the material can be used as an excellent electro-catalytic oxygen production electrocatalyst

Recovery method of VPO catalyst

Abstract: The invention provides a recovery method of a VPO catalyst. The recovery method includes the following steps that 1, vanadyl pyrophosphate and sodium carbonate are mixed, the mixture is calcined at high temperature, and then the mixture is cooled to room temperature; 2, a product obtained in the step 1 is put in hot water, the material is filtered, filtrate is obtained, the filtrate is subjected to freezing crystallization, trisodium phosphate crystals are obtained, the material is filtered, and the trisodium phosphate crystals and crystallization mother liquor are obtained; 3, a precipitatoris added into the crystallization mother liquor, wherein the precipitator is one or more of aluminum sulfate, magnesium sulfate, ammonium sulfate and magnesium chloride; a flocculant is added into thecrystallization mother liquor for assisting in filtering, and the pH value of filtrate is adjusted to be 7-10 with acid; the material is filtered and subjected to impurity removal, and a sodium metavanadate solution is obtained; and 4, ammonium salt is added into the sodium metavanadate solution, vanadium precipitation is carried out, and ammonium metavanadate is obtained. By means of the recovery method of the VPO catalyst, vanadium and phosphorous can be effectively separated, the vanadium recovery rate is increased to the maximum degree, and vanadium losses are reduced.