Stability and rheological characterization of colloidal gas aphrons: influence of xanthan gum and sodium dodecyl sulfate

Abstract

This study explores the stability and rheological properties of colloidal gas aphrons (CGAs) prepared with varying concentrations of xanthan gum (XG) and sodium dodecyl sulfate (SDS). Static stability was assessed by monitoring CGA volume changes over time in a graduated cylinder, while dynamic flow behavior was analyzed using a rotational rheometer to measure yield stress and viscosity at different shear rates. Rheological models were employed to characterize CGA behavior. The results showed that increasing the concentrations of XG and SDS enhanced the structural stability and viscoelastic properties of CGAs. The CGAs exhibited non-Newtonian fluid behavior, which the Herschel-Bulkley-Papanastasiou model accurately described. Yield stress and viscosity increased with higher XG concentrations, demonstrating the system’s ability to maintain high viscosity at low shear rates while exhibiting shear-thinning behavior at higher shear rates. An optimal combination of XG and SDS concentrations was identified, which improved CGA stability, prolonged liquid retention, and minimized bubble coalescence. These findings provide important insights into how CGAs remain stable and flow. This knowledge will help in using CGAs in different industries and environmental processes.