Thermo-Modulated Nanofibrous Skin Covered Janus Membranes for Efficient Oil/Water Separation

Abstract

An efficient membrane with good antifouling ability in various complex separation environments is crucial for long-term oily wastewater treatment. Herein, a thermo-modulated nanofibrous skin covered Janus membrane was successfully developed via a scalable synergetic electrospraying/electrospinning method. By introducing carbon nanotubes, the substrate exhibited superhydrophobicity and achieved separation of oil/water mixtures with high fluxes (> 6000 L m−2 h−1) and efficiencies (> 99%) under gravity. Moreover, benefiting from synergistic effect of poly(N-isopropylacrylamide) (PNIPAM) brushes and beadlike skin surface, the opposite thermoresponsive membrane exhibited improved wettability and water permeability (average from 774.6 to 947 and max = 1022.7 L m−2 h−1) with temperature varied from 20 ℃ (below the lower critical solution temperature) to 50 °C (above the lower critical solution temperature). Additionally, the hydrophilic side had high oil-in-water emulsion separation fluxes (max = 979.6 L m−2 h−1) and separation efficiencies of > 98% under gravity. Most importantly, the material showed excellent antifouling and cleaning ability resulting from thermoresponsive property. With the water temperature increased from 20 °C to 50 °C during the cleaning process of the membrane, the flux recovery ratio increased from 59.3% to 82.8%, and the irreversible fouling ratio correspondingly decreased from 40.7% to 17.2%. The thermo-responsive cleaning ability of coating is less limited to the material and morphology of the substrate, which provides a new vision for the antifouling method of membrane. The novel thermoresponsive Janus membrane demonstrated a good oil-water separation performance and remarkable antifouling ability which has a wider application prospect.