Chemical fronts and waves travelling in reaction-diffusion systems frequently induce
hydrodynamic flow. This adds an additional transport process to the mechanism of spatio-temporal
structure formation and can lead to an acceleration of the chemical (reaction) front.
We report on the acceleration of travelling chemical fronts elicited by convection,
as caused by the Marangoni effect in the monostable iodate-arsenous acid reaction
in a thin liquid film. At a stoichiometric excess of iodate over arsenous acid, the
reaction produces a large amount of iodine, which is surface-active. At the reaction
front, iodine is transferred from the bulk to the surface inducing spatio-temporal
gradients of surface tension that lead to capillary flows. These flows, in turn, promote
further iodine adsorption at the surface through hydrodynamic mixing effects. As a
consequence, an acceleration of the chemical fronts is observed, even if the concentration
difference across the front is constant. After the transient acceleration of the reaction
front, it settles at a constant propagation velocity, which is assumed to be regulated
by a balance in the mass transfer between the bulk and the surface.
