Chemical Complexing of AgI-NaI Aerosols

Abstract

An x-ray diffraction study of AgI-NaI aerosols produced from a standard solution generator has revealed the formation of several hydrated phases. The aerosol samples were collected on glass filter paper and analyzed continuously in a controlled atmosphere chamber at 23C, with exploratory runs at 0C, at vapor pressures ranging from 2.5 mb to saturation values. At 4.5 (+1, ?1.5) mb and 23C the aerosol transforms from a 3.9:1 weight ratio of dry AgI and NaI to 3.1:1 weight ratio of AgI and NaI·2H2O. At 8.1 (±1) mb there is a 60% loss in free AgI with formation of 3AgI·2NaI·nH2O (4<n<10). At 11.7 (±1) mb the double salt phase breaks down to form pure AgI immersed in an aqueous solution of NaI and AgI. Exploratory runs made at low temperatures reveal other compounds, one of which may be NaI·5H2O. Kinetic observations at the lower temperatures indicate that the hydrous phases may persist in aerosols released from airborne generators but would be eliminated before cloud base is reached when the aerosol is produced from ground generators.