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1

A facile synthesizing method of vanadium dioxide by pyrolyzing ammonium metavanadate

Qi J., Ning G., Hua R., Tian M., Liu S.

Materials Science Poland

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2012

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Vol. 30, No. 2

151--157

EN

A facile process was developed for synthesizing vanadium dioxide (VO2) by pyrolyzing ammonium metavanadate (NH4VO3) in nitrogen flow. The process was designed on the base of thermodynamic modeling of chemical reaction and thermal analyzing of NH4VO3 pyrogenation in N2 gas, and optimized by experiments. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to characterizing the product VO2. Thermo-gravimetric analysis (TG) and DSC were used for analyzing the process of NH4VO3 pyrogenation. The experimental results indicated that VO2 microcrystal particles were successfully synthesized. The product VO2 presents two kinds of micro morphologies, torispherical and pentagonal prism. The phase transition mainly takes place at 338.4 K and 341.9 K. The average enthalpy of the phase transition is 28.82 J/g.

2

Utilization of the post – filtration lye from the soda-chlorine-saltpetre method of soda production

Drużyński S., Trypuć M., Kiełkowska U., Mazurek K.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 4

53-56

EN

The optimal conditions were determined for the precipitation of ammonium metavanadate from the solutions of ammonium nitrate with the use of sodium metavanadate. The experiments were performed with the molar ratio of salts NH4NO3:NaVO3 1.5:1 at temperatures 293, 303, 313 and 323 K. Based on the obtained results, the optimal time of the process was determined as 5 h at 293–303K. Under these conditions, the achieved yield of the precipitation process was ~98.7%, while the contents of the vanadium salts in the post – filtration solution was ~0.02%.

3

Optymalne parametry precypitacji metawanadanu amonu z ługu pofiltracyjnego pochodzącego z otrzymywania sody z azotanu sodu

Trypuć M., Drużyński S.

Przemysł Chemiczny

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2009

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T. 88, nr 6

722-727

4

Solubility of ammonium metavanadate in potassium bicarbonate water solution

Trypuć M., Kiełkowska U., Białowicz K., Mazurek K.

Polish Journal of Chemical Technology

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2004

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Vol. 6, nr 2

53-55

EN

The solubility of ammonium metavanadate in potassium bicarbonate water solution at the temperatures 293 K and 303 K is reported. The concentration of vanadium(V) was determined using a spectrophotometric method while applying hydrogen peroxide. The potassium ion concentration was measured by weight in the form of potassium tetraphenylborate (K[B(C6H5)4]). The concentration of NH4+ ions was measured using the distillation method. The results were used to construct part of the polythermal solubility surface for the NH4VO3 + KHCO3 + H2O system. In addition, the solution density dependence versus the potassium metavanadate concentration expressed in mass % is presented.

5

Solubility investigations in the NaVO3 + NH4HCO3 + NH4VO3 + NaHCO3 + H2O system

Trypuć M., Kiełkowska U.

Polish Journal of Chemical Technology

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1999

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Vol. 1, nr 1

40-44

EN

Mutual salts solubility in the NaVO3 + NH4HCO3 + NH4VO3 + NaHCO3 + H2O system at temperature 303 K and the carbonization degree (R) of 90% has been studied. On the basis of the compiled data, a solubility polytherm section in the oblique projection on plane according to Janecke has been plotted. It has been found out that ammonium metavanadate is a sparingly soluble salt, NH4VO3 and NaHCO3 compose the stable pair of salts, whereas the triple points P1, P2 are represented by solutions convergently saturated. A thorough knowledge of the solubility isotherm course for the reciprocal salt pairs system is essential for an elaboration of sodium carbonate production technology based on NaVO3 as an initial reactant.