Дослідження кінетики осадження нікелю з розчину

Abstract

Background. In the nickel-containing catalysts production there is the technological stage of the intermediate insoluble nickel compounds. The studies of the nickel precipitation kinetics by the urea from the nickel nitrate solution were carried out that are useful for the design and characteristics calculation of these processes,Objective. The purpose is in constructing of mathematical model for the nickel precipitation process.Methods. A thermodynamic evaluation of possible reactions in solution was carried out. In isothermal conditions at the temperatures of 90 and 100 °C the kinetic curves of nickel precipitation from solutions were obtained at different initial concentrations. On the curves several sections were marked: the induction period and the main reaction period that are analyzed by different methods. The dependence of the induction period value from the conditions of the process was analyzed using multiple regression approach. The kinetic equation of first order reaction was chosen for the main period and the temperature dependence of the rate according to Arrhenius equation was determined.Results. It is established that the value of the induction period depends on the process temperature and the concentration of nickel, the regression equation was obtained. It is shown that the basic section of the precipitation process kinetic curves are described by the equation of the first order at the different initial concentrations of metal in all the investigated temperature range, reaction rate constant of the first order and the activation energy of the process were calculated.Conclusions. The proposed kinetic model of precipitation that consists of equations system for calculating the time of reaction was obtained. The value of the activation energy of the process indicates a kinetic stage of process tendency.