Abstract
The reaction of γ-FeOOH, which is present in the condensate water of power plants, with nickel hydroxide in high-temperature water was investigated. When γ- FeOOH powder adhering to nickel hydroxide is heated, NiFe2O4 is formed simultaneously with α-Fe2O3 by dehydration of γ-FeOOH. The rate of the dehydration reaction of γ-FeOOH can be described by Avrami's equation. Its activation energy in water is about 15 % less than that in nitrogen gas. After the formation of NiFe2O4, the diameter of the particles is larger than that before the reaction. The specific surface area of particles decreases with reaction time. The dissolved oxygen concentration in water has no effect on the reaction of γ-FeOOH with nickel hydroxide. When pH is lower than 5, dissolution of the reacted particles is accelerated and the fraction of NiFe2O4 in the particles increases. The variation of NiFe2O4 fraction with time was examined with the equation of the product of nickel permeation fraction inside the particles and the dehydration rate equation of γ-FeOOH (Avrami's equation).
