Effect of hydrophobic surface modifying macromolecules on differently produced PVDF membranes for direct contact membrane distillation

•Effect of hydrophobic SMM on the performance of the PVDF membrane.•Membranes prepared by phase inversion and electrospun nonofiber techniques.•SMM modified PVDF membrane used for DCMD.•Long time performance of SMM modified PVDF membranes.

Hydrophobic surface modifying macromolecules (SMM) and pore forming poly(vinyl pyrrolidone) (PVP) were added to fabricate poly(vinylidene fluoride) (PVDF)-PVP-hydrophobic SMM composite membranes through the phase inversion process. The composite PVDF-SMM nano-fibers membranes were also fabricated. The SMM was characterized in details by nuclear magnetic resonance spectroscopy. The membranes were characterized using the contact angle, liquid entry pressure of water, scanning electron microscopy, and porometry measurements. Both cast and nanofiber membranes were tested by direct contact membrane distillation (DCMD) with feed 3.5 wt% NaCl solution. Finally, the membrane performance of cast and nanofiber membranes was compared. The prepared hydrophobic SMM modified PVDF electro-spun nano-fibers membranes when combined with the casted membranes are very promising in DCMD for sea water desalination after running for 48 h operational timeframe.