Synthesis of ZIT composite material and immobilization of Nd2O3.

Zn 2 TiO 4 , the main ingredient of ZIT (Zinc Titanate) composite material, was prepared with ZnO and TiO 2 as raw materials, and its influencing factors were investigated just like temperature, the molar ratio of raw materials, and the sintering process. The research results show that the Zn 2 TiO 4 obtained by sintering the raw materials with 1.5:1 M ratio of ZnO and TiO 2 at 1000 °C for 4 h in NaCl–KCl molten salt has the highest purity and the best morphology. Subsequently, with Zn 2 TiO 4 as the main component, by adding CaHPO 4 , SiO 2 , B 2 O 3 , and Nd 2 O 3 , ZIT ceramic waste form was prepared through pre-sintering, sintering, and heat-treatment process. The influence of different mass fractions of Nd 2 O 3 in ZIT ceramic waste form on the properties of samples was studied, and the maximum Nd 2 O 3 content of ZIT ceramic waste form was finally determined to be 45 wt%. The densities of different samples were also determined by using the Archimedes principle, and the result shows that the densities are approximately between 3.5 g·cm−3and 4.5 g cm−3. Besides, the chemical stability of ZIT ceramic waste form with Nd 2 O 3 was explored through the PCT-B static immersion method and ICP test method. The study found that the leaching rate of ZIT ceramic waste form was relatively high at the initial stage of immersion and then gradually decreased. After soaking for 7 days, it gradually became stable. Finally, the 28-day leaching rate stabilized at the order of 10−6 g m−2 d−1. [ABSTRACT FROM AUTHOR]