Simulation of nucleation, growth, and aggregation of nonaparticles in supercritical water

A simulation model was developed for predicting the particle size evolution in hydrothermal synthesis of nanoparticles in supercritical water. Four elementary kinetic processes, including hydrothermal synthesis reaction, nucleation, growth, and aggregation, were involved based on the population balance equations (PBEs). The homogenous nucleation of metal oxide nanoparticles started at the operation time of 3.72μs. When the rate constant of hydrothermal synthesis reaction lnk increased from 2.8 to 6.16, the nucleation rate increased by three orders of magnitude (10²¹-10²⁴particles/m³·s) and the nucleation period reduced from 0.2s to less than 0.02s. The APS decreased by approximately half when a ten-fold smaller growth rate constant was adopted in the range of 10^-11-10^-8.