Crosshatched nanofibre membranes for direct contact membrane distillation

Abstract

We develop crosshatched nanofibre membranes from hydrophobic polymer, poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) for direct contact membrane distillation. The membranes are fabricated with a unique crosshatched structure that is achieved by lamination of alternating layers of aligned electrospun nanofibres. This membrane structure significantly improves water flux by reducing the tortuosity of the membrane and increases mechanical strength compared to electrospun structures with a random fibre orientation. In addition, we fabricate the top layer of the membrane using electrospun fibres with a bead-on-strings morphology which further increases the hydrophobicity by increasing the surface roughness, minimising pore wetting. Herein, we illustrate that the crosshatched nanofibre membranes with the bead-on-strings structure exhibit great water flux and mechanically robust structures for continuous operations, resulting in a water flux of 65 kg m−2 h−1 and 99.99 % rejection with steady performance over 100 h.