Enhancing Zinc Oxide Nanofluid Stability: Technical Insight on Surfactant Selection

ABSTRACT Achieving a low interfacial tension (IFT) is a crucial parameter for making nanofluids effective for various applications, including oil recovery and thermal fluid applications. ZnO nanoparticles are promising nanomaterials that demonstrate robust chemical properties. However, the continuous sedimentation of particles in the fluids rendered the ZnO nanofluids less effective. Five surfactants were selected to stabilize ZnO nanoparticles in terms of colloidal stability, viscosity, and IFT, which included sodium dodecyl benzene sulfonate (SDBS), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMM), oleic acid, and cetyltrimethylammonium bromide (CTAB). Zeta potential measurements and FESEM micrographs revealed moderate electrostatic stabilization and good particle distribution. The viscosity varied from 1.10 to 1.70 cP, indicating that the rheological behavior of the fluids relies on the nanoparticle dispersion. The IFT reduction trend ranged from 5.88% to 35.29%, demonstrating that surfactants can alter the performance of ZnO nanofluids. The ZnO‐SDBS nanofluids exhibited the highest reduction trend of 35.29%. ZnO‐CTAB showed a significant reduction in IFT (29.41%) with low viscosity (1.10 cP), indicating that the surfactant is more suitable for low‐resistance flow applications. ZnO‐PMM nanofluids unveiled poor interaction, making them insignificant. These findings are consequential in selecting surfactants for ZnO, making them ideal for enhanced oil recovery (EOR) and thermal fluids technology.