LDHs/TA-modified hybridized PAN/PVDF-HPF electrospinning membrane for emulsion separation

Membrane materials are widely used in the treatment of oily wastewater. In this work, hybrid nanofibrous membranes of polyacrylonitrile (PAN) and polytetrafluoroethylene-hexafluoropropylene (PVDF-HPF) were prepared by electrospinning and cured at high temperature. Subsequent hydrothermal treatment to grow Mg/Al-LDHs and polymerization of tannic acid (TA) on the surface yielded WPPLT membranes. SEM and EDS tests showed that the WPPLT membranes had a uniform compositional distribution. AFM tests showed that the hydrothermal and tannic acid treatments increased the roughness of the membranes and imparted a superhydrophilicity to the membranes. Separation tests of the emulsion showed that the separation efficiency was above 99 % with stable flux due to the fine pore size of the nanofiber membrane and the positive charge effect of the LDHs. Mechanical tensile tests showed that the tensile strength of the WPPLT membrane was 4.1 MPa, which was 89 % higher relative to the electrospinning membrane. Finally, the synergistic effect of LDHs and tannic acid under UV irradiation achieved more than 90 % degradation efficiency of methylene blue (MB). The present work provides new insights to improve the mechanical properties of nanofiber membranes, which helps the membranes to be used in more complex environments and enhances the prospect of their application in oil and water pollution.