Superhydrophobic/Superoleophilic Polyacrylonitrile/Ag Aerogels for the High Efficient Oil/Water Separation and Sensitive Detection of Low‐Concentration Oily Sudan Dyes

Abstract The detection of low‐concentration oily pollutants, especially when in oil/water mixtures or real food matrix, still faces great challenges. Integrating adsorption and plasmonic hot‐spot on single material will be an efficient method for ultra‐sensitively detecting oily dyes or contaminants in oil/water mixtures via surface‐enhanced Raman scattering. Herein, the superhydrophobic/superoleophilic polyacrylonitrile (PAN)/Ag aerogels which can quickly absorb and detect low‐concentration oily dyes in oil/water mixtures are successfully fabricated. In order to solve the contradiction that abundant hydrophilic‐Ag nanoparticles are adverse to the superhydrophobicity of substrate but in favor of Raman signals, the superhydrophobic/superoleophilic PAN/Ag aerogels are prepared through two steps: substrate‐seeding and secondary‐growth. The lowest detection concentration of 10⁻¹² m for oil‐soluble Sudan III in oil/water mixtures is achieved by using PAN/overgrown Ag (PAN/O‐Ag) nanofibrous aerogels as absorbent, which is superior to most of reported materials. Moreover, a detection limit of 0.1 ppm of Sudan III spiked in chilli powder is obtained using PAN/O‐Ag aerogels.