Gas/Aerosol Chemical Reactions in the NaOH-SO₂-H₂O System

Abstract

The hydrolysis of a solid NaOH microparticle in humid nitrogen and the chemical reaction between the resulting NaOH solution microdroplet and SO 2 gas have been studied with the use of elastic and inelastic (Raman) light scattering. A single solid NaOH particle was levitated electrodynamically in a reaction chamber and exposed to water vapor. After hydrolysis/deliquescence, the resulting solution droplet was exposed to SO 2 gas. Raman spectra and elastic resonance spectra collected during the reactions indicate that low SO 2 concentrations in the gas phase yield NaHSO 3 while high SO 2 concentrations result in Na 2 SO 3 as the product. These results indicate that the reversibility of the key reactions becomes important when the SO 2 concentration is low.