Superhydrophilic and underwater superoleophobic hydrogel-loaded fabrics for enhanced oil/water separation

Abstract

Separating oil/water mixtures in highly acidic, alkaline, and saline environments poses a significant challenge. This study presents a method for preparing stable hydrogel-loaded nonwoven fabrics capable of separating oil/water mixtures in such harsh conditions. The double network (DN) hydrogel-loaded nonwoven fabrics were fabricated by combining the in-situ copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) with acrylamide (AM) and the physical freeze-thaw treatment of polyvinyl alcohol (PVA). This DN hydrogel exhibits an extremely low swelling degree (equilibrium swelling ratio = 0.37 g/g) and imparts excellent hydrophilic and underwater oleophobic performance (underwater oil contact angle >150°) to the loaded nonwoven fabrics. Additionally, owing to the unique structure formed by the hydrogel on the fabric surface, it demonstrates outstanding resistance to acids, alkalis, and salts. The material enables efficient oil/water separation in H2SO4, NaOH, and seawater solutions. The hydrogel-loaded nonwoven fabrics achieved a high oil/water separation efficiency of over 99 %, a water flux of more than 40,000 L/(m2·h), and maintained high stability even after 100 cycles of operation.