Fundamental investigation of the drying of solid suspensions

In this work, a comprehensive series of experiments is conducted to investigate the drying behaviour of micro- and nano-sized particle dispersions. To this end, an acoustic levitator was used to study the drying kinetics of single droplets. The temporal evolution of the actual droplets was recorded using a CMOS camera and the solid grains produced at the end of drying were investigated by SEM imaging. At the end of drying, the grains show different morphologies as a function of the particle size, concentration and initial droplet volume. We combine these experimental data to show the drying behaviour is dependent on all the parameters and that the data all collapses when plotted against Péclet number. This resulted in a novel characteristic diagram which allows one to predict the shape of the dried colloidal droplet based on Pé. Our results extend the fundamental understanding of the mechanisms controlling drying of droplet suspensions