Efflorescence and deliquescence of airborne particles

Abstract

The theoretical models based on classical nucleation theory are employed to investigate efflorescence/crystallization relative humidity (ERH) of single-inorganic particles and multi-inorganic particles, and study effects of water soluble organics (WSOs) on ERH of single-inorganic particles. The theoretical predictions are in good agreement with the experimentally measured values; Kelvin effect plays an important role in raising the ERH of suspended nanoparticles; and WSOs depress the ERH of single-inorganic particles. In this thesis, theoretical investigation is conducted for the first time to explore the deliquescence of sodium chloride particles deposited on a substrate. Unlike the deposited particles larger than 500 nm, the deliquescence relative humidity of smaller particles can substantially depend on the particle size, contact angles, and surface tension between the particle and the atmosphere. At certain contact angles, small particles depositing on a substrate could deliquesce at a much lower RH.