On liquid evaporation from droplets of colloidal solutions of SiO2 and Fe2O3 nanoparticles

Liquid evaporation from Fe 2 O 3 and SiO 2 nanocolloid droplets has been studied. The geometry of the droplets has been juxtaposed with the intensity of light transmitted through them. It has been established that the droplet evaporation process may be divided into a number of stages, with each of them being distinguished by a certain type of the behavior of suspended nanoparticles. The regularities of the formation of ring-shaped deposits, which are referred to as coffee-rings in the literature, have been investigated. The main features of the structures of the ring-shaped deposits resulting from evaporation of different dispersions are the same. The time of complete liquid evaporation determined by spectrometry has appeared to be longer than the time determined by visual monitoring of droplet geometry. A model has been proposed for the evaporation of droplets of colloidal solutions of nanoparticles.