Interfacial and Structural Properties of Different Natural Surfactants Extracted From Venezuelan Junin Extra Heavy Crude Oil

Abstract

In this work, acids, asphaltenes, maltenes, and acid-free asphaltenes were isolated from Venezuelan Junin extra heavy crude oil, and their interfacial properties studied using the pendant drop method. This study led to the conclusion that the acids present in the crude, which have molecular weights of about 400 Da and are present in higher concentrations in asphaltenes, account for the decrease in the interfacial tension. In other words, asphaltenes act as molecular traps for acids. Furthermore, it was possible to confirm with simpler methods that substances adsorbed at the water–crude oil interface have low molecular weights.