Electrospun nanofiber membranes incorporating fluorosilane-coated TiO2 nanocomposite for direct contact membrane distillation

•The fabrication of ENMs with addition of modified TiO2 particle to dope solution for MD.•The effect of hydrophobic TiO2 nanoparticle embedded in fibers on properties of ENMs.•Improved ENMs with 149° of contact angle or 194.5 kPa of LEP by addition of 10% TiO2.•The evaluation of DCMD performance with functionalized ENMs by TiO2 particles.•DCMD without deterioration of water productivity and quality in 20% PH with 10% TiO2.

The electrospinning technique as a method for fabricating hydrophobic membranes for membrane distillation (MD) has received much attention in recent times. In this study, TiO2 functionalized with 1H,1H,2H,2H-perfluorooctyltriethoxysilane was added directly to the dope solution for electrospinning in order to increase the hydrophobicity of the resulting MD membranes. Three concentrations (10%, 15% and 20%) of polyvinylidene fluoride-co-hexafluoropropylene (PH) dope solution were used for electrospinning with various amounts of TiO2 (1%, 5% and 10%) to generate nanofibers. The electrospun nanofiber membrane (ENM) of 20% PH with 10% TiO2 exhibited the highest surface hydrophobicity (contact angle=149°) resulting from good dispersion of the TiO2 particles, while the highest liquid entry pressure of 194.5 kPa was observed for the ENM comprising 10% PH with 10% TiO2 due to its reduced pore sizes. Furthermore, the ENMs containing 10% TiO2 exhibited better flux and stable salt rejection than commercial and ENMs without TiO2. Notably, there was no severe wetting in the 20% PH ENM with 10% TiO2 over seven days of operation, despite the high salt concentration (7.0 wt% NaCl) of the feed water.

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