Innovative use of eco-friendly stearate-modified iron oxide nanoparticles in stabilization of water in oil emulsion for corrosion protection of mild steel in corrosive low water cut -crude oil systems

Eco-friendly amphiphilic stearic acid-modified iron oxide (SAIO) nanoparticles were implemented to inhibit the corrosion of mild steel in a corrosive water-in-crude oil (W/O) system. The SAIO nanoparticles reduced the interfacial tension (IFT) by around 20 %, resulting in a stable W/O emulsion with smaller droplets. The W/O emulsion was stable for over 90 days at room temperature and 3 days at 50 °C. At room temperature, the emulsion with the optimum concentration of SAIO showed stability in acidic, neutral, and alkaline conditions. SAIO’s ability to prevent corrosion of mild steel was found to be pH dependent. Above 1 mg/ml SAIO, a high water contact angle of 140° indicated lower wettability and reduced water phase interaction of the steel surface. As a result, SAIO nanoparticles inhibited steel corrosion in the corrosive W/O media by a factor of two. In addition, SAIO nanoparticles could be almost entirely recovered from the W/O system via demulsification when exposed to a magnetic field. The research demonstrates that eco-friendly SAIO nanoparticles can prevent steel corrosion by “locking” the water phase in W/O systems by interfacial manipulation which are recoverable and reusable.