Formation Of Basic Salts Research Articles

Granulated Anti-Icing Reagent on the Basis of Dehydrated Magnesium and Calcium Nitrates

The phase composition of the product of thermal dehydration of a mixture of crystallohydrates of magnesium and calcium nitrates with a bulk composition Mg(NO3)2 · Ca(NO3)2 ⋅ 2.7H2O is determined via X-ray phase analysis and its IR spectrum is obtained. It is found that the sample solidifies upon cooling to form a compact nonhygroscopic mass. A sample with a higher concentration of water is hygroscopic and deliquescent in air. Deeper dehydration is accompanied by hydrolysis with the formation of basic salts. The anti-icing properties of the dehydrated nitrate sample are determined.

Anionic carbonate activation of layered (α+β) nickel hydroxide

Nickel hydroxide is widely used as the active material in supercapacitors. Samples of Ni(OH)2 with the (α+β) layered structure, synthesized in the slit-diaphragm electrolyzer, are the most active. The possibility of carbonate activation of layered (α+β) Ni(OH)2 was studied by the synthesis of samples in the slit-diaphragm electrolyzer using a mixture of sodium hydroxide and sodium carbonate as the electrolyte. The molar part of sodium carbonate in the NaOH+Na2CO3 mixture was controlled by acid titration in the presence of two indicators. The synthesis of nickel hydroxide samples was conducted at the molar part of carbonate from 0.16 (NaOH without the additional introduction of carbonate) to 0.83. The crystal structure of the samples was studied by means of X-ray diffraction analysis, electrochemical characteristic – by means of cyclic voltammetry and galvanostatic charge-discharge cycling in the accumulator regime. By means of XRD analysis, it was found that upon increasing the molar part of carbonate in the anolyte to 0.49, the crystallinity of the monophase layered (α+β) structure increases. It was found that a further increase of the carbonate part results in a more amorphous structure due to a partial breakdown of the hydroxide lattice with the formation of basic salts and formation of the bi-phase system. This conclusion is supported by cyclic voltammetry and discharge curves. The study of the electrochemical characteristics revealed, that for the molar part of carbonate below 0.39, carbonate activation of hydroxide occurs resulting in an improved specific capacity. Increasing the carbonate part to 0.49 results in a lower specific capacity, and even further increase results in the breakdown of hydroxide into basic salts and a significant drop in electrochemical activity. Thus, it was found, that to achieve the maximum activating effect, the optimal molar part of sodium carbonate (in a mixture with sodium hydroxide) should be about 40 %. The specific capacity of nickel hydroxide under this optimal condition is 234 mA·h/g, and this sample is found to be susceptible to activation with cobalt compounds, which further improved capacity to 254 mA·h/g.

EFFECT OF INORGANIC ACID SOLUTIONS ON ELECTROCHEMICAL BEHAVIOR OF TIN ELECTRODE

The electrochemical behavior of tin metal was studied in some inorganic acid solutions; HCl, HNO3, H2SO4 and H3PO4, using the open circuit potential measurements and the potentiodynamic polarization technique. In addition, the metallographic structure of tin electrode was examined before and after immersion in test solution by using scanning electron microscope (SEM). The identification of the elements presented in the surface of specimen after immersion in different solutions was performed using an energy dispersion X-ray analysis(EDAX). The obtained results demonstrated that the aqueous dilution of HCl, H2SO4 and H3PO4 retarded the corrosion of tin electrode, (hydroxyl ion plays a part in basic salt formation), while dilution of HNO3 acid accelerated the corrosion. It is evident from SEM image that, there were grain boundaries and the surface was more active and rougher in case of mechanically polished electrode. In non-polished electrode, the surface was covered with a protective layer; generally SnO2. In potentiodynamic polarization study, the formation of basic salt Sn(OH)Cl was preference to any other oxide in HCl solutions. The increase in NO2 concentration was responsible for the increase in the rate of dissolution in HNO3. The tin dissolution in sulphuric acid occurred through an intermediate of (SnHSO4OH) species.