--> Abstract: Identifying Electrostatic Interactions in Aqueous and Non-Aqueous Media Using Atomic Force Microscopy and Extended DLVO Theory, by Michael J. Bower, Tracy L. Bank, and Rossman F. Giese; #90084 (2008)

Datapages, Inc.Print this page

Identifying Electrostatic Interactions in Aqueous and Non-Aqueous Media Using Atomic Force Microscopy and Extended DLVO Theory

Michael J. Bower1, Tracy L. Bank2, and Rossman F. Giese3
1MS Student, Department of Geology, SUNY-Buffalo, Buffalo, NY
2Assistant Professor, Department of Geology, SUNY-Buffalo, Buffalo, NY
3Professor, Department of Geology, SUNY-Buffalo, Buffalo, NY

In non-aqueous media, such as petroleum products, colloidal stability is poorly characterized and modeled. However, an understanding of colloidal stability is vital to the petroleum industry as it influences the recovery and processing of unconventional resources, as well as the efficiency of engine oils. In this research we investigate the effects of different additives (i.e. surfactants, urea) on colloidal stability in decane, a major component of commercial oils. Some additives that improve oil efficiency contain Zn and Ca which generate electrostatic charges and decrease colloidal coagulation by increasing electrostatic repulsions. In some systems, urea is used as an additive to enhance colloidal coagulation and thus increase filtration and lengthen oil lifetimes.

We have used Atomic Force Microscopy (AFM) to measure the interfacial forces between polystyrene colloids and a glass surface in decane and in water. Preliminary results show that electrostatic interactions, which dominate colloidal stability in aqueous solutions, were significantly reduced in the non-polar decane. In future experiments, we will measure iron-oxyhydroxide colloid stability in decane and decane treated with various chemical amendments in order to represent a more geologically relevant, engineered system. Extended-DLVO (XDLVO) theory will be used to describe the van der Waals, electrical double layer, and acid/base interactions based on the total free energy of each system. XDLVO modeling will utilize surface contact angles and zeta-potential measurements to determine the total free energy of the system. This research will improve our understanding of the fundamental mechanisms of various chemical amendments and recovery techniques in the petroleum industry.

Presented AAPG Eastern Section Meeting, Pittsburgh, Pennsylvania 2008 © AAPG Eastern Section