Fluorine-free superhydrophobic PET fabric with high oil flux for oil–water separation

Superhydrophobic fabrics with high oil–water separation efficiencies have recently attracted considerable attention because of the frequent oil pollution created by industry. However, the relationship between hydrophobicity and the separation efficiency needs to be clarified, and water-blocking materials used to separate heavy oil must be further explored. In this study, we prepared hydrophobic fabrics by a one-pot sol–gel approach with different concentrations of hexadecyltrimethoxysilane (HDTMS), polymethylhydrosiloxane (PMHS), and hydroxyl-terminated polydimethylsiloxane (HTPDMS). The surface chemistries of the superhydrophobic fabrics were systematically studied, and it was found that the SiO2 nanoparticles created a micro/nanoscale roughness on the surface, endowing the fabric with superhydrophobicity. By changing the component ratios, five samples with elevated hydrophobicity were fabricated. Interestingly, the hydrophobicity of the fabric had a positive effect on the separation efficiency and the oil flux. Importantly, when the contact angle increased from 132.5° to 151.3°, the oil flux of heavy oil increased from 13,028 ± 563 L m−2 h−1 to 20,473 ± 928 L m−2 h−1. The superhydrophobic fabric also exhibited a high resistance to mechanical abrasion and self-cleaning properties. Thus, we provide a pollution-free, anti-oil fouling, high-oil-flux, high-separation-efficiency, water-blocking fabric for the separation of oils from water.