Evaluation of interfacial modification of green ZnO Janus nanoparticles at the water-oil interface via fluid-fluid and fluid-rock experiments

The application of Janus nanoparticles (JNPs) in enhanced oil recovery (EOR) has attracted considerable attention due to their superior interfacial activity compared to homogeneous nanoparticles (NPs). In this work, the synthesis and EOR performance of bio-based zinc oxide (bio-ZnO) JNPs derived from biosynthesized ZnO NPs using a zinc acetate precursor was assessed. The JNPs were fabricated via a Pickering emulsion-based asymmetric modification strategy with (3-aminopropyl)triethoxysilane (APTES) and characterized by FTIR, FESEM, DLS, and zeta potential measurements. The colloidal stability, interfacial tension (IFT) reduction, wettability alteration, and oil displacement efficiency were evaluated against commercial ZnO NPs. The bio-ZnO JNPs exhibited amphiphilic character with a dual-peak zeta potential distribution (−15 and + 29 mV), confirming successful Janus formation. They achieved a remarkable IFT reduction from 28 to 3 mN/m at 1000 ppm. The wettability index reached 0.91 at 500 ppm and 0.97 at 1000 ppm, compared to 0.56 and 0.63 for commercial ZnO at the same concentrations. Micromodel flooding experiments demonstrated that the JNPs improved oil recovery to 60% in unfractured and 68% in fractured porous media, substantially outperforming commercial ZnO nanofluids (32% and 36%, respectively).