Water desalination using graphene-enhanced electrospun nanofiber membrane via air gap membrane distillation

Abstract

This study demonstrates the preparation and desalination performance via air gap membrane distillation (AGMD) of a graphene-loaded electrospun nanofiber membrane. Different concentrations of graphene (0–10wt%) were incorporated in/on electrospun polyvinylidene fluoride-co-hexafluoropropylene (PH) membrane to obtain a robust, and superhydrophobic nanocomposite membrane. The results showed that graphene incorporation has significantly enhanced the membrane structure and properties with an optimal concentration of 5wt% (i.e., G5PH). Characterization of G5PH revealed membrane porosity of >88%, contact angle of >162° (superhydrophobic), and high liquid entry pressure (LEP) of >186kPa. These favourable properties led to a high and stable AGMD flux of 22.9L/m2h or LMH (compared with ~4.8 LMH for the commercial PVDF flat-sheet membrane) and excellent salt rejection (100%) for 60h of operation using 3.5wt% NaCl solution as feed (feed and coolant inlet temperatures of 60 and 20°C, respectively). A two-dimensional dynamic model to investigate the flux profile of the graphene/PH membrane is also introduced. The present study suggests that exploiting the interesting properties of nanofibers and graphene nanofillers through a facile electrospinning technique provides high potential towards the fabrication of a robust and high-performance AGMD membrane.