Robust polytetrafluoroethylene (PTFE) nanofibrous membrane achieved by shear-induced in-situ fibrillation for fast oil/water separation and solid removal in harsh solvents

Abstract

Facing the severe pollution in modern industry, membrane separation is widely used to treat the wasted solvents owning to its low cost, high efficiency, and scalability. Microporous polytetrafluoroethylene (PTFE) membranes have been proved to be an ideal choice for waste separation owing to its excellent chemical resistance and low adhesion, but there are still challenges due to the poor processability of PTFE. Herein, we proposed an innovative shear-induced in-situ fibrillation methodology to prepare PTFE nanofibrous membranes, which successfully solve the dilemma between high porosity and ultrafine pore sizes of conventional microporous PTFE membranes. The achieved ultrafine nanofibrous membrane simultaneously has high porosity of 75%, fine pore size of 0.16 μm, and thin thickness of 10 μm. Consequently, the membrane not only shows outstanding mechanical properties with an ultrahigh tensile strength of up to 27.4 MPa, but also exhibits super-hydrophobicity/oleophilicity, chemical resistance, and anti-fouling behavior for fast separation or filtration in harsh solvents. For both oil/water emulsion and solid/liquid solution, a separation efficiency of more than 99.9% can be obtained, while permeate fluxes as high as 5197 L⋅m−2⋅h−1 and 36,929 L⋅m−2⋅h−1⋅bar−1 were achieved driven by gravity and pressure, respectively. This study opens promising avenues for the fabrication of robust and anticorrosive PTFE nanofibrous membranes with high separation efficiency by using a facile, green, and cost-effective in-situ fibrillation strategy.