# Diffusiophoretic Enhancement of Mass Transfer by Nanofluids

## TL;DR

This study demonstrates that nanofluids can enhance mass transfer through diffusiophoretic effects, with experimental results aligning with theoretical predictions, enabling controlled manipulation of solute transfer rates.

## Contribution

The paper provides experimental validation that diffusiophoresis causes mass transfer enhancement in nanofluids, clarifying the underlying mechanism.

## Key findings

- Dye front velocity matches diffusiophoretic velocity estimates.
- Enhanced mass transfer observed in nanofluids due to nanoparticle motion.
- Potential to control solute transfer using tailored nanofluids.

## Abstract

Observations of an enhanced mass transfer in nanofluids have led to several propositions for the underlying cause, but none of them have been clearly established. Here, we reproduce the enhancement phenomenon within a glass capillary containing fluorescein di-sodium dye solution on one side and alumina nanoparticle suspension on the other, avoiding convective interferences present earlier. The enhancement is explained by the counter-convective motion of the dye solution in response to the diffusiophoretic motion of the nanoparticles towards a higher concentration of the dye. The velocity of the dye front agrees with the theoretical estimate obtained from the diffusiophoretic velocity of alumina nanoparticles in a gradient of fluorescein di-sodium electrolyte solution. With a suitably chosen nanofluid, it should now be possible to effect the enhancement (or suppression) of mass transfer of a given solute.