Metal-ligand complexation and electrostatic interaction triple cross-linked superhydrophilic stainless steel mesh membranes for highly robust oil-water separation

Stainless steel mesh (SSM) membranes demonstrate exceptional oil-water separation flux and efficiency, yet suffer from compromised durability due to oil fouling, wear, and chemical corrosion under prolonged usage. To enhance robustness, a method for SSM preparation employs triple cross-linking of phytic acid (PA), polydopamine (PDA), and polyethyleneimine (PEI), capitalizing on the complexation of hydrophilic phosphate groups of PA onto SSM surface by Fe(III) released from SSM during high-temperature alkaline treatment and liberated during PA/PEI immersion. A PDA/PA dual crosslinking layer was constructed on the SSM surface with PDA and PA, overcoming limitations of PDA in alkaline conditions and single crosslinking sites. Triple cross-linking via Michael or Schiff base reactions, metal coordination, and electrostatic interaction enhances membrane robustness. Tuning PEI concentration chelated with PA controls PA/PEI nanoparticle dispersion and aggregation, enabling phase separation to form papillate superhydrophilic/underwater superoleophobic membranes with micro/nano-structuring. These membranes achieve a flux of 67750.56 L·m −2 ·h −1 and 99.99 % efficiency, remaining reusable for 50 cycles. They exhibit remarkable durability, withstanding significant physical wear and chemical corrosion. After 40 sandpaper abrasions, the membranes maintain a flux of 61664.89 L·m −2 ·h −1 and 99.86 % efficiency. Thus, these superhydrophilic SSM with papillary micro/nanostructures demonstrate exceptional stability and corrosion resistance.