Characterizing Aqueous Foams by In-situ Viscosity Measurement in a Foam Column

TL;DR

This paper introduces a novel method to measure foam viscosity in-situ during foam decay, providing deeper insights into foam stability and aging, surpassing traditional foam height measurements in sensitivity and efficiency.

Contribution

The study presents an innovative approach combining foam column tests with real-time viscosity measurement using a vibration viscometer, enabling detailed analysis of foam aging behaviors.

Findings

Foam viscosity drops sharply during early decay phase.

The method is more sensitive and faster than traditional foam height measurements.

It effectively characterizes foam stability across different surfactant and gas combinations.

Abstract

Foam characterization is essential in many applications of foams, such as cleaning, food processing, cosmetics, and oil production, due to these applications diversified requirements. The standard characterization method, the foam column test, cannot provide sufficient information for in-depth studies. Hence, there have been many studies that incorporated different characterization methods into the standard test. It should be enlightening and feasible to measure the foam viscosity, which is both of practical and fundamental interest, during the foam column test, but it has never been done before. Here, we demonstrate a method to characterize aqueous foams and their aging behaviors with simultaneous measurement of foam viscosity and foam height. Using a vibration viscometer, we integrate foam column experiments with in-situ foam viscosity measurements. We studied the correlation among the foam structure, foam height, and foam viscosity during the foam decay process. We found a drastic decrease in foam viscosity in the early foam decay while the foam height remained unchanged, which is explained by coarsening. This method is much more sensitive and time-efficient than conventional foam-height-based methods by comparing the half-life. This method successfully characterizes the stability of foams made of various combinations of surfactants and gases.