Investigation of the mechanism of nickel hydroxide formation from nickel nitrate
Autor: | Vadym Kovalenko, Valerii Kotok, Dmitriy Girenko, Mykola Nikolenko, Dmytro Andreiev, Volodymyr Verbitskiy, Volodymyr Medianyk, Svetlana Morozova, Rovil Nafeev |
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Rok vydání: | 2023 |
Předmět: |
α-modification
nitrate-doped nickel hydroxide conductometry nickel hydroxide Applied Mathematics Mechanical Engineering Energy Engineering and Power Technology two-stage formation mechanism Industrial and Manufacturing Engineering Computer Science Applications potentiometry Control and Systems Engineering Management of Technology and Innovation Environmental Chemistry nickel nitrate Electrical and Electronic Engineering Food Science |
Zdroj: | Eastern-European Journal of Enterprise Technologies. 1:58-65 |
ISSN: | 1729-4061 1729-3774 |
DOI: | 10.15587/1729-4061.2023.272673 |
Popis: | Nickel hydroxides are widely used as electrochemically active substances in alkaline batteries and hybrid supercapacitors; they can be used for electrocatalysis, in electrochemical sensors, and as pigments. Knowledge of the formation mechanism of nickel hydroxides is necessary for developing and optimizing targeted synthesis methods. The thermal effects of processes in the formation of nickel hydroxide from nitrate were studied by the calorimetry method. The mechanism of precipitate formation was investigated by the method of simultaneous potentiometric (with a glass universal electrode) and conductometric titration. The nickel content in the samples obtained at the determined NaOH/Ni2+ratios was investigated by the chemical method of trilonometry after preliminary dissolution. Calorimetric investigations showed that the reaction of nickel nitrate with NaOH was exothermic with ΔНreaction=‒28328.5J/mol. The exothermic nature of the NaOH dilution process was revealed with ΔНdilution=‒2454J/mol. According to the results of potentiometric titration, the formation of a basic salt of the NiOHNO3type was not detected. Analysis of the results of conductometric titration revealed a two-stage chemical mechanism for the formation of nickel hydroxide from nitrate. At the first stage, which had a high rate, due to the liquid-phase reaction of the nickel cation with the hydroxyl anion, a primary precipitate of the composition Ni(OH)1.87(NO3)0.13 was formed. In the second stage, as a result of a slow topochemical reaction of the primary precipitate with hydroxyl anions, nitrate ions were displaced from the precipitate to form nickel hydroxide. These data are confirmed by the analysis of precipitate obtained at NaOH/Ni2+ratios of 1.87 and 2.2: the Ni content was 52.95% and 55.63%, corresponding to the formulas Ni(OH)1.87(NO3)0.13∙0.68H2O and Ni(OH)2∙0.71H2O. This clearly indicated that the primary precipitate was nitrate-doped α-Ni(OH)2and the final precipitate corresponded to the α-modification of nickel hydroxide |
Databáze: | OpenAIRE |
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