Abstract View
The Prediction of Size and Charge of Particles Generated in an Electrospray System
HAO ZHOU, Pratim Biswas, Washington University in St Louis
Abstract Number: 308
Working Group: Aerosol Physics
Abstract
Electrospray system attracts significant attention for the generation of uniform charged particles from nanometer to micrometer. The accurate prediction of final particle size and charge is critical in efficient utilization of electrospray method to synthesize nanomaterials. However, the evaporation of highly charge droplet often involves in various highly coupled processes such as Coulombic fission and solute/nanoparticle diffusion, which pose a challenge to predict the final size and resultant charge of the particles for different types of precursors. In this work, a holistic model accounting for solvent evaporation, solute/nanoparticle diffusion, collision and aggregation of nanoparticle inclusions, Coulombic fission and ion evaporation processes was developed. First, the model equations are cast into nondimensional form for generalization. Nondimensional governing parameters are derived and their influence on the final particle size was investigated by numerically solving the governing equations for two cases: dissolved solute and nanoparticle inclusions. The simulation shows that the non-dimensional characteristic diffusion time, non-dimensional characteristic coagulation time and Coulombic fission related loss have a major influence on the final particle size. Based on the relative magnitude of these parameters, there exists different scenarios for particle size. Then, an analytical expression to predict the final particle size was derived for both dissolved solute and the nanoparticle inclusion condition, in the case of slow drying. Finally, the relationship between the particle charge and size is investigated. An equation to predict final particle charge is proposed.