Dynamic interfacial tension behavior of acidified oil/surfactant-enhanced alkaline systems 1. Experimental studies

Abstract

Experimental investigations have been conducted to elucidate the fundamental mechanisms for the lowering of interfacial tension between acidic oil and surfactant-enhanced alkaline solutions. A model acidic oil has been used to examine the effects of various alkali and added surfactant concentrations on dynamic interfacial tension. Experimental results revealed the existence of a characteristic behavior exhibited by the acidified oil against aqueous solutions. The dynamic interfacial tension is a function of acid concentration, alkali concentration, and added surfactant concentration. It has been found that there exists an optimum concentration with respect to both alkali and added surfactant, at which the interfacial tension is the lowest. The optimum concentration has been found to be dependent on acid concentration. The results presented here suggest that the unionized acid contributed to the lowering of the dynamic interfacial tension between the model acidic oil and alkali and added surfactant solutions. The results also suggest that the unionized acid, ionized acid and added surfactant adsorbed simultaneously onto the interface, resulting in low dynamic interfacial tension.