Supraparticle formation from colloidal suspensions via superheated steam drying

The present work focuses on investigating the effect of superheated steam drying on supraparticle formation from nanosuspensions of colloidal silica (8, 20, and 95 nm) at 5, 15, and 30 wt%. The supraparticle formation is studied by single droplet drying at 105 °C, 200 °C, and 300 °C. It is shown that by increasing superheated steam temperature, single droplets reached the locking point earlier and bigger supraparticles are obtained. Moreover, single droplets containing bigger nanoparticles resulted in larger supraparticles after drying at otherwise same conditions. Average particle porosity up to 75% is achieved at high superheated steam temperature. Finally, scanning electron microscope images reveal that even at high temperatures, no significant vacuoles are formed, which means that the void space is very well distributed throughout the particle.