Integrating functionalized magnetite nanoparticles with low salinity water and surfactant solution: Interfacial tension study

In this study, citric acid-coated magnetic (CACM) nanoparticles (NPs) were synthesized and utilized as an interfacial tension (IFT) reduction agent. In addition, the effect of three types of salts at different concentrations up to 150,000 ppm was investigated. These salts, NaCl, CaCl2, and MgCl2, showed the IFT values of 19.34, 16.24 and 12.23 mN/m, respectively, at the optimum salinity condition. The IFT decreased swiftly with increasing brine concentration at the beginning and then, increased after the optimum point due to the effect of asphaltenes and salts, respectively. Meanwhile, CACM NPs indicated a very significant capability to reduce the IFT value down to 3.99 mN/m without using any surfactant. The CACM NPs, among the other NPs used in this study, have shown a key role in IFT reduction due to their acidic feature (these NPs were coated by citric acid). Consequently, the combination of the NPs with surfactant at low salinity condition, showed major changes (for Fe2O3 and SiO2 NPs) and minor changes (for CACM NPs) at the interface as the movement of the surfactants by the NPs to the interface increases the surface-active agents at interface for reducing the IFT. The findings of this study can help to gain a better understanding of the IFT behavior using magnetite NPs in combination with surfactant at low salinity condition.