Preparation and modification of PVDF-HFP electrospun nanofiber membranes using fluorinated graphene oxide for membrane distillation (MD) application

Electrospun nanofiber membranes (ENM) have received increasing interest in membrane distillation (MD) applications due to their unique properties including high hydrophobicity and porosity. On the other hands, they suffer from wetting. In this paper, a synthesized fluorinated graphene oxide (0.1 and 0.5 wt%) was used to electrospin a dual-layered polyvinylidene fluoride-co hexafluoropropylene (PVDF-HFP) membranes in order to promote the hydrophobicity of the membranes. The prepared membranes were characterized in terms of the thickness (100- 140 µm), porosity (86-82%), water contact angle (137 -144 ), mean pore size (~ 2 µm), and morphological characteristics. the ENM loaded with 0.1 wt% of nanoparticles (NP) showed better hydrophobicity (contact angle of 144 ), without much change in the other characteristics. The morphological studies confirmed a good adhesion of NPs to fibers and two electrospinning layers. Also, direct contact membrane distillation (DCMD) test showed good pure and salt solution flux, 51 kg.m-2. s-1 and 50 kg.m-2. s-1, respectively, together with a low permeate conductivity (1.5 µS.cm-1). The dual-layered graphene oxide membranes showed a decrease in flux along with a significant drop of permeate conductivity which indicates better salt rejection.