  We investigate mass transfer during absorption of atmospheric trace soluble
gases by a single droplet whose size is comparable to the molecular mean free
path in air at normal conditions. It is assumed that the trace reactant
diffuses to the droplet surface and then reacts with the substances inside the
droplet according to the first order rate law. Our analysis applies a
flux-matching theory of transport processes in gases and assumes constant
thermophysical properties of the gases and liquids. We derive an integral
equation of Volterra type for the transient molecular flux density to a liquid
droplet and solve it numerically. Numerical calculations are performed for
absorption of sulfur dioxide (SO2), dinitrogen trioxide (N2O3) and chlorine
(Cl2) by liquid nanoaerosols accompanied by chemical dissociation reaction. It
is shown that during gas absorption by nanoaerosols the kinetic effects play
significant role, and neglecting kinetic effects leads to significant
overestimation of the soluble gas flux into a droplet during all the period of
gas absorption.
