Homogeneous Precipitation Method To Prepare Nano Co <sub> 3 </ Sub> The O <sub> 4 </ Sub>

In this paper, Co3O4 nano-particles were prepared by homogeneous precipitation method, technical conditions and kinetics were studied, The main contents and results are as follows:Co(NO3)2 6H2O was used as raw materials, and CO(NH2)2 was used as precipitator, Co3O4 nano-particles were prepared by homogeneous precipitation. The influences of concentration, molar ratio of reactants, reaction temperature and time, dryness temperature and time, and calcining temperature and time on particle size were investigated. The results showed that cubic, dispersed Co3O4 nano-particles with average diameter of 20nm were obtained under optimize conditions.To determine influence of technical conditions on product diameter, the influences of concentrations, molar ratio, reaction temperature and time on average size were investigated by means of uniform design. The results of experiments indicated that product diameter was mostly influenced by reaction temperature, followed by molar ratio of reactant, concentration of reactants, and reaction time. The optimum conditions were C(Co(NO3)2 6H2O)=0.35mol/L, n(CO(NH2)2):n(Co(NO3)2 6H2O)=3.53 : 1, reaction temperature 94 and reaction time 3.53h. Under these conditions Co3O4 nano-particles with average diameter of 22nm were obtained.Influences of disperants on preparing Co3O4 nano-particles were studied, and TG-DTA, XRD, TEM and IR absorption spectra were used to characterize the samples.The results showed that shapes and sizes of Co3O4 nano-particles could be controlled and modified by dispersants. The diameter was about 20nm when PEG(40mg/mL) was used as dispersants, while the diameter was 10nm and the length is 0.2um for PAANa(15mg/mL).The kinetics of homogeneous precipitation was studied, the activation energy was about 100.19kJ/mol, and reaction index was 1.42.The TG and DTA techniques were used to research the decomposition kinetics of depositions. The decomposition mechanism and kinetics-equation were investigated according to Phadnis methods, and the equation can be depict as follow:The kinetics parameter of decomposition were obtained by using Kissinger methods. The activation energy was 162.41kJ/mol and reaction index was 1.30.