Bipolar membrane assistant landfill leachate coagulation by bauxite tailings with oxalic acid

The facile fabrication of high-performance polymer composite membranes poses a challenging task. Herein, poly (3, 4-ethylenedioxythiophene) (PEDOT) selective layer was deposited onto the surface of porous polyvinylidene fluoride (PVDF) substrate by a simple vapor phase polymerization (VPP) method, resulting in the fabrication of high-performance composite separation membrane PEDOT/PVDF. This composite membrane has excellent separation performance to separate model wastes in water systems. For instance, the rejection rates for differently charged neutral red (NR), Azure Ⅱ (Azu Ⅱ), congo red (CR), and methylene blue (MB) were 99.1 ± 0.2 %, 99.2 ± 0.2 %, 99.4 ± 1.5 %, and 97.9 ± 1.0 %, respectively, with corresponding permeances of 42.3 ± 2.4 L m-2h−1 bar−1, 60.1 ± 1.9 L m-2h−1 bar−1, 25.1 ± 5.6 L m-2h−1 bar−1, and 68.2 ± 4.9 L m-2h−1 bar−1. PEDOT/PVDF composite membrane demonstrated excellent chemical stability, and the rejection rate of NR decreased by only 4.1 % during 48 h of continuous filtration. In the environment of NR solution (50 ppm) at 60 °C or Azu Ⅱ-NaOH solution (pH 13), it maintained high selectivity (>96 %) while significantly improving permeability (>80 L m-2h−1 bar−1). The entire fabrication process of high-performance PEDOT/PVDF membrane was conducted at room temperature, with high versatility simple operation and minimal equipment requirement, offering significant advantage compared to similar reported membrane materials. This work provides a useful reference for the facile fabrication of high-performance separation membranes.