(640b) Effects of Cationic and Anionic Ions on Nanosurfactant Performance: Colloidal Stability and Interfacial Tension Study

Developing nanosized carriers for surfactant molecules is imperative for multiple applications such as oil recovery, emulsion stability and wettability control. However, colloidal stability and functionality at high temperature and salinity conditions are normally the main challenges to utilize the nanomaterials for practical applications. Herein, utilizing sub-100 nanometers oil-swollen micelles; NanoSurfactant, which consists of petroleum sulfonate surfactant stabilized with a zwitterionic surfactant, is reported. The stability of the petroleum sulfonate in high salinity brine (56 g/L) and temperature (90^oC) is studied in the presence of NaCl, CaCl₂, MgCl₂ and Na₂SO₄ individually and combined together. The effect of the individual salts on the colloidal stability is investigated utilizing dynamic light scattering and multi-wavelength LUMiSizer^®. Moreover, the dynamic adsorption at crude oil-water interface is examined utilizing spinning drop tensiometer technique. The results indicate that the presence of the cations facitilate the interaction between the petroleum sulfonate and the zwitterionic molecules. Moreover, the NanoSurfactant suspension in different brine conditions were stable for more than 14 days at a temperature of 90^oC. Finally, the NanoSurfactant prepared in 4 wt% NaCl brine had the lowest interfacial tension reduction between crude oil- water from 10 mN/m to 0.002 mN/m. The results presented here provide a better understnding of the compatability of NanoSurfcatnt solutions under different sality conditions and the underlying mechanisim of the adsorption at the oil-water interface.