Imaging of chemical kinetics at the water-water interface in a free-flowing liquid flat-jet

TL;DR

This paper demonstrates a novel liquid flat-jet technique to measure chemical kinetics at a clean water-water interface, enabling diffusion-based analysis without turbulent mixing.

Contribution

It introduces the use of flat-jet liquid microjets for precise kinetic measurements at liquid interfaces, avoiding turbulence and rapid mixing.

Findings

Clean interface observed in the first leaf of the flat-jet chain

Chemiluminescence reaction kinetics successfully measured using this setup

Diffusion-driven kinetics analysis achieved without turbulent mixing

Abstract

We present chemical kinetics measurements of the luminol oxydation chemiluminescence reaction at the interface between two aqueous solutions, using liquid jet technology. Free-flowing iquid microjets are a relatively recent development that has found its way into a growing number of applications in spectroscopy and dynamics. A variant thereof, called flat-jet, is obtained when two cylindrical jets of a liquid are crossed, leading to a chain of planar leaf-shaped structures of the flowing liquid. We here show that in the first leaf of this chain the fluids do not exhibit turbulent mixing, providing a clean interface between the liquids from the impinging jets. We also show, using the example of the luminol chemiluminescence reaction, how this setup can be used to obtain kinetics information from friction-less flow and by circumventing the requirement for rapid mixing but by intentionally suppressing all turbulent mixing and instead relying on diffusion.