# Hydrodynamic signatures of stationary Marangoni-driven surfactant transport

## TL;DR

This study experimentally investigates steady Marangoni-driven surfactant transport on water interfaces, revealing how different surfactants influence flow dynamics based on their adsorption and dissolution properties, without prior chemical knowledge.

## Contribution

It introduces a hydrodynamic measurement method to distinguish surfactant transport regimes without needing detailed chemical properties.

## Key findings

- Low concentration surfactants cause adsorption-driven flow.
- High concentration surfactants lead to dissolved surfactant-driven flow.
- The method effectively characterizes unknown surfactants like camphoric acid.

## Abstract

We experimentally study steady Marangoni-driven surfactant transport on the interface of a deep water layer. Using hydrodynamic measurements, and without using any knowledge of the surfactant physico-chemical properties, we show that sodium dodecyl sulphate and Tergitol 15-S-9 introduced in low concentrations result in a flow driven by adsorbed surfactant. At higher surfactant concentration, the flow is dominated by the dissolved surfactant. Using Camphoric acid, whose properties are {\it a priori} unknown, we demonstrate this method's efficacy by showing its spreading is adsorption dominated.