The prediction of size and charge of particles formed from evaporation of charged droplets generated in an electrospray system

Electrospray systems are an effective methodology for generating uniform submicrometer sized charged droplets, initially containing a dissolved solute or nanoparticle inclusions, producing particles from the droplets. In this work, we develop a model for charged droplet drying to predict the final size and resultant charge of the particles. The model accounts for solvent evaporation, solute/nanoparticle diffusion, the collision and aggregation of nanoparticles, coulombic fission and ion evaporation processes. The competition among these subprocesses determines the final size and charge. The model equations are cast into nondimensional forms for generalization. The governing dimensionless parameters are derived and their influences on the final particle size and charge are investigated numerically. The most important parameters are the non-dimensional characteristic diffusion time, non-dimensional characteristic coagulation time, non-dimensional flow rate and coulombic fission related loss. An analytical solution is obtained in the case of slow drying. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Electrospray systems are used to generate submicrometer sized charged droplets containing solute or nanoparticles, which are then transformed into particles. A model for charged droplet drying was developed to predict the final size and charge of particles, considering processes such as solvent evaporation, diffusion, coagulation, and fission. The study investigates the influence of dimensionless parameters on particle size and charge, with an analytical solution obtained for slow drying conditions.