Fabrication of PVDF nanofibrous hydrophobic composite membranes reinforced with fabric substrates via electrospinning for membrane distillation desalination

To improve the mechanical properties of the electrospun nanofibrous membrane, the nonwoven fabrics and spacer fabrics were employed as support substrates to fabricate polyvinylidene fluoride (PVDF) nanofibrous composite membranes. The influences of the substrate on membrane morphology, hydrophobicity, pore size and pore size distribution, porosity, mechanical strength and permeabilitywere comprehensive evaluated. The electrospun composite membranes had a three dimension bead-fiber interconnected open structure and a rough membrane surface. The membrane surface presented a multilevel re-entrant structure and all the water contact angles were above 140 degrees. In contrast with the pure PVDF nanofibrous membrane, the stress at break and the elasticmodulus of the composite membranes increased by 4.5-16 times and 17.5-37 times, respectively. Since the spacer fabrics had less resistance to mass transfer, the membranes composited with spacer fabrics exhibited greater permeate fluxes compared with the composite membranes with the nonwoven fabrics as substrates. During the membrane distillation test, the highest permeate flux was up to 49.3 kg/m(2)/hr at the feed temperature of 80 degrees C. The long-time and repeat operation of membrane distillation desalination indicated the fabricated membrane with a good resistance to scaling andwetting. The results suggested the potential of the electrospun composite membrane for membrane distillation application. (c) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.