Synergy among Surfactants in Solution and on Particles in Suspensions

Authors: Shaohua Lu and Ponisseril Somasundaran, Columbia University, New York, NY.

Venue: 81st ACS (American Chemical Society) Colloid & Surface Science Symposium, University of Delaware, Newark, DE, June 24–27, 2007 (http://www.engr.udel.edu/Colloids2007/) [external site]).

Abstract: Surfactant mixtures are widely used in detergent, personal care, enhanced oil recovery, and flotation applications. Adsorption of nonionic/cationic/anionic (ex: n-dodecyl-â-D-maltoside(DM), and sodium dodecyl sulfonate) on solids such as alumina was studied in this work at different solution conditions of pH, mixing ratio and salt contents along with the wettability and zeta potential. Solution interactions were studied by analytical ultracentrifuge, surface tension, small-angle neutron scattering, and cryoTEM. It was found that surfactant adsorption is dramatically affected under certain pH conditions. The effects of pH, however, are reduced by synergistic interactions in the case of nonionic/anionic mixtures. Surface tension results reveal a negative interaction parameter, suggesting that there are synergistic interactions between them. Importantly, only one peak indicative of one type of micelle was identified using analytical ultracentrifugation in the case of the above anionic/nonionic mixtures, while two types of aggregates were observed in the case of nonionic/nonionic mixtures. The above information on surfactant aggregation helps to reveal the mechanisms of interactions between surfactants, as well as their efficient application in various industrial processes.

Related NETL Project: The overall objective of the related NETL project DE-FC26-03NT15413, “Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery,” is to understand the role of mineralogy of reservoir rocks in determining interactions of reservoir minerals and their dissolved species with externally added reagants (surfactants/polymers) and their effects on solid-liquid and liquid-liquid interfacial properties, such as adsorption, wettability, and interfacial tension. A further goal is to devise schemes to control these interactions in systems relevant to reservoir conditions. Particular emphasis will be placed on the type and nature of different minerals in oil reservoirs.

NETL Project Contacts
NETL – Betty Felber (betty.felber@netl.doe.gov or 918-699-2031)
Columbia U. – P. Somasundaran (ps24@columbia.edu or 212-854-2926)