Magnetically Responsive Functionalized V ₂ O ₅ Nanobelt for Sustainable and Energy-Efficient Crude Oil–Water Separation

The extraction of crude oil from subsurface reservoirs results in intimate mixing of the oil with water forming a highly stable oil–water emulsion. Conventional demulsification methods apply chemical demulsifiers coupled with thermal energy to separate crude oil from water. This process often requires high temperatures for prolonged periods, making the process highly energy intensive. To reduce the cost of operation, the present study introduces a novel magnetic nanomaterial-based reusable demulsifier that enables oil–water separation at significantly lower temperatures. The magnetic nanodemulsifier (MND) was synthesized by depositing cobalt ferrite (CoFe2O4) nanoparticles onto a vanadium pentoxide nanobelt (V2O5) via facile interfacial adsorption-assisted assembly. The surface of the nanobelt was amine-functionalized with 3-aminopropyltriethoxysilane (APTES). The synthesized nanomaterial was extensively characterized using various analytical methods, such as Fourier transform infrared spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, energy-dispersive X-ray spectroscopy, zeta potential, and vibrating sample magnetometry. The demulsification performance of the MND was tested on a stable laboratory-prepared crude oil–water emulsion via a bottle test and UV-visible spectroscopy of the separated water. A 100% separation efficiency of the MND was recorded at 40 °C and dosages as low as 100 ppm. The used MND was recovered magnetically and recycled and reused with a separation efficiency up to 90% until the fifth cycle. A possible mechanism is proposed explaining the functionality of the prepared MND involving electrostatic attraction between oppositely charged nanostructures and emulsion droplets, leading to displacement of asphaltenes from the interface and subsequent adsorption that weakens the oil–water interface.