Abstract: AgO-loaded diatomite composite was prepared by chemical oxidation-deposit method using potassium persulfate as oxidant. The composite was characterized by X-ray diffraction, scanning electron microscope and the laser particle size analyzer. The process and kinetic behavior of thermal decomposition of the composite were studied by means of thermogravimetry. The results show that the AgO-loaded diatomite composite with a AgO content(mass fraction) of 12.7% is made up of tetragonal christobalite and monoclinic silver peroxide. The size of the composite is in the range of 0.614—116.5 μm and the median-particle-size and specific surface area of the composite are 18.53 μm and 203.32 m²/kg, respectively. The composite decomposes at 171 ℃ along with the formation of silver oxide followed by decomposing into silver at higher temperature. The mechanism of decomposition reaction is random nucleation and subsequent growth mechanism(A1), and the apparent activation energy and reaction frequency factor are 131.37 kJ/mol and 3.19×10¹³ s^-1, respectively. Compared with reference silver peroxide powders, the thermal decomposition temperature of the composite rises and a considerable increase of the activation energy up to 40 kJ/mol was observed.

Key words: AgO, Diatomite, Thermal decomposition, Kinetics, Reaction mechanism