Fenton pre-activated grafted modified PVDF membrane and its application in DCMD desalination

As an efficient membrane separation technology, membrane distillation (MD) technology has broad application prospects in desalination of marine and high-salt wastewater. However, membrane fouling/wetting is still the main factor limiting the industrialization of MD technology. In this paper, a polyvinylidene fluoride (PVDF) micro/nano superhydrophobic membrane was prepared using Fenton pretreatment combined with a surface grafting method. Membrane surface hydrophobicity, chemistry and morphology were characterized using measurements of water contact angle (WCA) and liquid entry pressure (LEP), along with observations using attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The grafted fluorinated SiO2 nanoparticles reduced the surface energy of the PVDF base membrane while at the same time increasing the surface roughness. After modification, the WCA of the PVDF base membrane surface increased from 99° to 155° and the LEP was enhanced from 204 kPa to 235 kPa. Furthermore, the composite membrane revealed stable performance due to the pre-activation by the Fenton solution. The proposed superhydrophobic composite membrane has a great potential to solve the problems of complex membrane pretreatment and prevent damage to the base membrane. The simple method demonstrated here also reduces costs which opens up multiple opportunities for applications in industry.