One-step water/NMP solvent exchange to prepare high-throughput hydrophilic L-TA/polyvinylidene fluoride membranes towards efficient separating oil-in-water emulsion

Abstract

In the pollution treatment process of offshore oil spill accidents, it was found that emulsified droplets were extremely difficult for oil-in-water emulsion separation because of their tiny particle size and the stability of the emulsion. In this paper, the L-Tartaric acid-modified PVDF composite membranes (0 wt%, 9 wt%, 12 wt%, and 15 wt% addition, L-TA/PVDF) were prepared in one step by a simple non-solvent induced phase transition method. The membrane could easily filter three oil-in-water emulsions (kerosene, peanut oil, and machine oil) by gravity alone. The SEM, AFM, water contact angle, and underwater oil contact angle tests showed that adding tartaric acid greatly increased the porosity and hydrophilic ability of the L-TA/PVDF composite membrane. The permeation flux of kerosene-in-water emulsion by L-TA12/PVDF composite membranes was increased to 4951.08 LMH bar⁻¹, which was 4.7 times that of PVDF membrane. Moreover, the separation efficiency of the L-TA12/PVDF membrane was kept as high as 90.6 % after 21 cycles of filtrations compared to 27.4 % of the pristine PVDF membrane. This characteristic indicated a stable hydration layer for the prepared membranes, thus leading to exhibit excellent fouling resistance. Hence, the L-TA/PVDF composite membranes with high permeation flux and excellent antifouling performance were prepared by a simple method, providing a new path for separating oil-water emulsions.