During the addition, the pH of the mixture decreased due to the hydrolysis of the salt.
The pH was maintained at 10.5 by the controlled addition of ammonia solution. After completion of the precipitation procedure, the Mg(OH)2 gel was transferred into the Milestone microwave oven (MicroSYNTH) operated at 350 W for 15 min. During the microwave irradiation, the temperature of the solution reached 80 °C.
The resulting precipitate was then cooled to room tem- prature, filtered, and washed with deionized water more than five times.
The solid obtained was dried at 120 °C for 1 h and calcined at 500 °C for 2 h to give the final product.