Electrospinning polyvinylidene fluoride/expanded graphite composite membranes as high efficiency and reusable water harvester

Reusable polyvinylidene fluoride (PVDF) membranes with inclusions of expanded graphite (EG) were developed by electrospinning methodology for water harvesting studies. Scanning electron microscopy (SEM) was used to perform morphological studies and they demonstrated that the inclusions of EG slightly increased the diameters of the electrospun fibers. Static water contact angle was measured to evaluate wetting phenomena. Hydrophobic surfaces were obtained for both samples with and without EG inclusions, while the composite membrane was found to have relatively high water contact angle. A setup was used to evaluate the water-retaining performance of electrospun composite samples. An improvement of 63.4% in water harvesting efficiency was obtained when EG was included. The morphology and wettability of membranes containing EG after water harvesting experiments remained the same as before. And the results suggested the composite membranes were reusable.