Synthesis and Interfacial Behavior of Decyl Methylnaphthalene Sulfonate

Abstract

High purity decyl methylnaphthalene sulfonate (DMNS) surfactant was synthesized. The purity of product was determined by HPLC, and the structure was confirmed by IR, UV, and ESI-MS. The surface and oil-water interfacial activities of DMNS surfactant were studied. The effects of concentrations of the surfactant, alkali, and inorganic salt on the dynamic interfacial behavior of crude oil/Shengli Oil Field/surfactant oil flooding systems were studied, and comparitive studies of systems with strong and buffered alkali were also carried out. Results showed that DMNS surfactant possessed great capability and efficiency for lowering solution surface tension and oil-water interfacial tension. The critical micelle concentration (cmc) was 0.02% and the surface tension at this concentration was 31.61 mN.m⁻¹. At proper concentrations of the surfactant, alkali, and inorganic salt, the dynamic interfacial tension between the crude oil of the Shengli Oil Field and the surfactant oil flooding system reached a minimum value of 10⁻⁵–10⁻⁶ mN.m⁻¹ in a very short time (3–20 min) and maintained an ultra-low value (< 10⁻² mN.m⁻¹) for a long period of time (15–87 min). The crude oil/surfactant systems presented satisfactory interfacial behavior. DMNS has great potential to be used in enhanced oil recovery (EOR) with low cost and high efficiency.

Keywords:

• decyl methylnaphthalene sulfonate
• surface tension
• interfacial tension
• enhanced oil recovery

ACKNOWLEDGMENTS

This work was carried out as a part of the National Key Basic Research Development Program (G1999022501). The authors are grateful for their financial support. We also thank the State Key Laboratory of Fine Chemicals, Dalian University of Technology, China, for sample analysis.