Estabilidade de espumas de soluções de tensoativos não iônicos: abordagem química e modelagem matemática

Abstract

The application of liquid foams has gained prominence in several segments of the industry. Thus, the study of obtaining and stability of foams in different physical and chemical conditions has been relevant and contributes to the construction of knowledge in the area of interfacial sciences. In this article, the main factors that influence the foam stability of solutions of three nonionic surfactants of different degrees of ethoxylation were studied. In order to characterize the complete saturation of the liquid gas interface, the tensiometry technique was used through the maximum bubble pressure method. The study demonstrated that factors such as surfactant concentration (CS), temperature (T), presence of salinity (CNaCl) and agitation time in the preparation of the foams (tω) can have a strong influence on the stability of the suds depending on the degree of ethoxylation of the surfactants and the degree of interactions between these factors. In addition, mathematical modellings were developed in the foam stability phases in order to predict the coalescence behavior of the bubbles over time, finding models of R² > 0.90 in almost all situations. The equations of adjustment parameters for the models were obtained by central compound experimental planning and also presented adjustments with R² > 0.90, reinforcing the predictive capacity of the proposed empirical models.