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The relatively large pore size of electrospun membranes might limit their application for direct contact membrane distillation (DCMD). Incorporation of ionic liquid is a potential approach to decrease the pore size of electrospun membranes, which was attributed to the increased conductivity of electrospinning solution. In this study, a novel nanofibrous membrane based on the blends of poly(vinylidene fluoride) (PVDF), polytetrafluoroethylene (PTFE) and ionic liquid (BMIMPF 6 ) was fabricated and applied for the DCMD. The effects of the BMIMPF 6 on the morphology, pore size and DCMD performance of the PVDF-PTFE nanofibrous membrane were investigated. Compared with neat (PVDF-PTFE) membranes (average pore size: 0.93 μm), the incorporation of BMIMPF 6 resulted in a smaller mean pore diameter (0.58 μm). The liquid entry pressure value of the modified composite membrane also increased from 62.75 kPa (neat) to 83 kPa, due to the decreased pore size. The composite membrane exhibited a longer lifespan (about 26 h) than neat membrane during long-term DCMD process, which makes this composite membrane a promising candidate for DCMD application.

This work describes the enhanced mechanical properties of composite polydimethylsiloxane/poly(methyl methacrylate) (PDMS/PMMA)/multi-walled carbon nanotubes (MWCNTs) nanofiber membrane and its application in the phenol separation from saline wastewater. MWNCTs with varied content were immobilized in the membrane matrix using electric field of electrospinning. The neat PDMS/PMMA and composite PDMS/PMMA/MWCNTs membranes were characterized by scanning electron microscopy, universal testing machine, contact angle measurement, 3D automatic optical profiler, and pore size analyzer. Results indicated that tensile strength of composite PDMS/PMMA/MWNCTs membrane was drastically increased six times with a water contact angle (WCA) of 163.3 due to increased roughness parameters compared to neat membrane. However, porosity and fiber diameter of PDMS/PMMA/ MWCTs membrane decreased with the increase of MWCNTs content. Moreover, phenol extraction efficiency of PDMS/PMMA/ MWNCTs membrane was found to be 34.5% higher than neat one with similar salt rejection efficiency of 99.97%. The stability of MWCNTs in the membrane matrix was confirmed by the cross-sectional morphology, which indicated the robust and novel design of membrane.

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