Water as the Pore Former in the Synthesis of Hydrophobic PVDF Flat Sheet Membranes for Use in Membrane Distillation
Although PVDF flat sheet membranes have been widely tested in MD, their synthesis and modifications currently require increased use of green and inexpensive materials. In this study, flat sheet PVDF membranes were synthesized using phase inversion and water as the pore former. Remarkably, the water added in the casting solution improved the membrane pore sizes; where the maximum pore size was 0.58 µm. Also, the incorporation of f-SiO2NPs in the membrane matrix considerably enhanced the membrane hydrophobicity. Specifically, the membrane contact angles increased from 96° to 153°. Additionally, other parameters investigated were mechanical strength and liquid entry pressure (LEP). The maximum recorded values were 2.26 MPa and 239 kPa, respectively. The modified membranes (i.e., using water as the pore former and f-SiO2NPs) were the most efficient, showing maximum salt rejection of 99.9% and water flux of 11.6 LMH; thus, indicating their capability to be used as efficient materials for the recovery of high purity water in MD.
Keywords:Direct contact membrane distillation, PVDF flat sheet membranes, superhydrophobic silica nanoparticles, water as the pore former
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