An aerosol chemical reactor for coating metal oxide particles with (NH4)SO4-H2SO4-H2O. 1. New particle formation

Abstract

In situ atmospheric measurements (notably single-particle mass spectrometry) show that tropospheric aerosols are internally mixed, including both water-soluble and insoluble components. This fact notwithstanding, most process study laboratory work has concentrated on water-soluble electrolytes because the generation of particles composed of both soluble and insoluble components is difficult to achieve in the laboratory. Even so, such an aerosol is essential for accurate process studies of atmospheric aerosols and for the quantitative calibration of single-particle mass spectrometers. In the completed work, particles composed of a (NH4)2SO4-H2SO4H 2O coating on a TiO2, Al2O3, or ZrO2 core are prepared in a novel chemical reactor, which is a tube furnace with a linear-temperature gradient along its longitudinal axis. Reactor controls on the number size distribution are reported, including the linear flow velocity, the SO3 vapor pressure, the NH3 vapor pressure, the reactor temperature gradient, and the presence or the absence of insoluble seed nuclei (viz. TiO2, Al2O3, and ZrO2).