Sustainable foam stabilization using red mud-derived nanoparticles for enhanced oil recovery and CO2 sequestration.

Foam has been widely used for enhanced oil recovery (EOR) and CO2 sequestration due to its ability to improve sweep efficiency and control gas mobility. However, foam instability poses challenges for long-term applications. While nanoparticles have been explored as foam stabilizers, their high cost and limited availability hinder large-scale use. This study investigates red mud-derived nanoparticles (RMNPs), synthesized from industrial waste, as an affordable and sustainable alternative to traditional foam stabilizers. RMNPs were produced by ball milling at varying milling durations, achieving sizes below 200 nm. Characterization of the RMNPs was conducted using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), zeta potential measurements, and particle size analysis. Foaming solutions were prepared with alpha-olefin sulfonate (AOS) anionic surfactant, with and without the RMNPs, in deionized water, seawater, and brines (NaCl and CaCl2), covering pH 3-11. Foam stability was evaluated via handshake tests and dynamic foam analyses using nitrogen and carbon dioxide gases. Results showed that incorporating RMNPs significantly enhanced foam stability, increasing foam half-life by up to 60% with nitrogen and 57% with CO2. Nanoparticles milled for 30 h yielded optimal performance, forming fine and uniform bubble structures. Zeta potential analysis confirmed strong hydrophilic properties of the RMNPs, promoting stability in aqueous solutions. pH sensitivity tests indicated optimal stability at pH 4-5, while highly acidic conditions (pH 3) negatively affected stability. This work highlights the potential of red mud-derived nanoparticles as a low-cost stabilizer for foam applications in EOR and CO2 sequestration, supporting further optimization under reservoir conditions.