pH-Responsive smart non-woven fabrics (NWFs) with double switchable wettability between superhydrophilicity–superhydrophobicity–superhydrophilicity to oil/water separation

Abstract

pH-Responsive smart non-woven fabrics (NWFs) with double transformations were prepared via the in situ grafting of Ag nanoparticles through an oxidation–reduction reaction and were modified using a mixed thiol-molecule solution, including HS(CH₂)₁₀CH₃, HS(CH₂)₁₀COOH and HS(CH₂)₁₁OH. A NWF continuously separates immiscible oil–water mixtures with high selectivity and has considerable flux under gravity. The wettability of NWFs with an optimal thiol concentration shows reversible switches between superhydrophilicity–superhydrophobicity–superhydrophilicity, which corresponds to different conditions such as acidic, neutral and basic. The as-prepared NWFs had great oil absorption capacities and possessed high oil–water separation efficiency. This simple approach to fabricate pH-responsive NWFs has provided a facile and versatile strategy for effectively separating oil–water mixtures, which can be further applied for water treatment, purification of solvents or fuels and so on.