Pendant drop tensiometry of milk-water solutions

Abstract

The surface tension of liquids were measured using the pendant drop tensiometry technique, which only requires the use of a needle, a camera, and a diffused light source. For certain liquids with known literature surface tension values, the experiment results agree well with the expected ones. We examine the effect of changing the concentrations of whole, low fat, and no fat milk to the surface tension of milk-water solutions. Low fat milk decreases the surface tension of the solution fastest in comparison with the other two. For all milk types, the solution surface tension decreased exponentially, which implies that the effect is greater at lower concentrations (<50%) than at higher concentrations. This phenomenon can be described by the Gibbs-Thomson equation, which relates surface tension, concentration, and surface adsorption.