Nanoparticle deagglomeration driven by a high shear mixer and intensification of low-speed stirring in a viscous system

Abstract

High shear mixers (HSMs), with their unique advantages of high shear forces and a wide operational range, are commonly used in nanoparticle deagglomeration. This study explores a novel approach to intensifying nanoparticle deagglomeration in a 100 mPa‧s viscous system using HSMs combined with low-speed stirring. The effects of main operating and structural parameters were experimentally investigated. The results show that the teethed HSM outperforms the blade-screen HSM, achieving a smaller attainable size (114 nm vs. 210 nm) and a higher fine particle generation fraction (46.08% vs. 18.77%). Increasing HSM size directly affects the energy input (from 6.478 MJ/kg to 31.879 MJ/kg), which influences the deagglomeration mechanism and kinetics but does not affect the smallest attainable size (117 nm). Higher solid contents improve energy efficiency, while low-speed stirring, though not altering the deagglomeration mechanism, enhances its kinetics. The process intensification factor (S) and energy efficiency factor (ε_m) were defined to evaluate the intensification of low-speed stirring. Increasing the impeller speed enhances this effect. The PBT impeller with a diameter ratio of 0.35 is identified as the ideal structure in this study, improving deagglomeration performance by 8.26% while reducing energy consumption by 8.3%. These results provide guidance for optimizing processes and improving deagglomeration performance through the combination of low-speed stirring in viscous systems for process industries.