Investigation of atmospheric nanoparticles: Impact of sea salt and fate of organic molecules adsorbed on alumina

Abstract

AbstractNanoparticles of simulated sea spray were investigated in the presence of ozone in a Teflon chamber, where photochemical experiments on droplets (above 76% relative humidity) with Br enrichments up to a factor of 6 released OH radicals, (2–6) × 106 cm–3, atomic Cl (2–10) × 104 cm–3 and atomic Br up to 3 × 108 cm–3. Sub‐micrometer sized agglomerates of nano‐sized fused silica and alumina particles in a glass chamber served for degradation experiments of the semivolatile compound octadecyl vinyl ether (ODVE). Adsorbates of ODVE at submonolayer thickness on such substrates were observed to hydrolyse rapidly to form 1‐octadecanol (within a few hours). Treating the particles with NaOH before coating diminished hydrolysis, and exposing an aerosol of Alumina C (Degussa), coated with ODVE, to gaseous OH radicals in a glass chamber delivered rate constants for the consumption of ODVE and its hydrolysis product, 1‐octadecanol, which need further interpretation in terms of volatilisation and surface properties. This study reports first aerosol smog chamber experiments on such nanoparticles in a new facility that can be cooled to –28 °C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)