Tunable nanostructured stainless-steel coating for high-selective and high-permeable separation membranes for oil/water emulsions

Abstract

This paper demonstrates a stainless-steel (SS) nano-pyramid structure (diameter of ~20–50 nm and pore size of 156.1 nm) sputter-coated on mixed cellulose ester (MCE) membrane for the use in separation of oil/water emulsions. SS-coated MCE membrane presented a superhydrophilic, antifouling surface as well as underwater superoleophobicity. The coated membrane achieved excellent separation efficiency of >99% when applied to light oil-water emulsions with a range of viscosities and densities. The highest permeation flux measured was 1,555 L m−2 h−1 when applied to toluene-in-water emulsions. The membrane also presented outstanding recyclability, as evidenced by oil rejection rate retaining at >99% through four separation cycles. The coated membrane was also shown to work well under harsh conditions including salty water, extreme pH values (1–14), and high temperatures (60 °C). In addition, our fabrication route of SS-coated MCE employs low process temperature while being highly scalable, which is favorable for industrial-scale applications.