Ultrathin conformal hydrogel-coated oil filter with tunable pore architecture for highly efficient oil-in-water emulsion separation

초록

The escalating discharge of oily pollutants from industrial activities poses severe threats to aquatic ecosystems and water resources. Although oil filter-based oil/water separation technologies have emerged as promising solutions, existing approaches suffer from limited treatment capacity, poor coating durability, and inadequate control over internal porous structures. Herein, we present an oil filter featuring an ultrathin conformal hydrogel layer chemically bonded to a polydimethylsiloxane (PDMS) sponge fabricated via PDMS-based Interconnection-Tunable Porous Ink (p-ITPI) technology, which enables independent tuning of pore size (similar to 150-500 mu m) and interconnection width (similar to 15-145 mu m). The chemically grafted hydrogel layer, formed through benzophenone-mediated UV polymerization, provides superhydrophilicity (<5 degrees contact angle) and underwater superoleophobicity while maintaining excellent mechanical durability. Dual separation mechanisms-Laplace pressure-driven blocking and size-exclusion-enable selective oil rejection. The engineered filter achieved high water flux up to 14.8 m & centerdot;h(-)& sup1; with oil separation efficiency exceeding 99.5% for oil/water mixtures under gravity-driven operation. The tunable interconnection width enables selective separation of oil-in-water emulsions by matching pore architecture to droplet size distributions. The filter maintained stable performance over 20 consecutive separation cycles without cleaning, demonstrating exceptional anti-fouling properties and operational stability.

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