title: Enhanced performance of PVDF nanocomposite membrane by nanofiber coating: A membrane for sustainable desalination through MD.
abstract: Membrane distillation (MD) is a promising separation technique capable of being used in the desalination of marine and brackish water. Poly(vinylidene fluoride) (PVDF) flat sheet nano-composite membranes were surface modified by coating with electro-spun PVDF nano-fibres to increase the surface hydrophobicity. For this purpose, the nano-composite membrane containing 7 wt.% superhydrophobic SiO2 nano-particles, which showed the highest flux in our previous work, was first subjected to pore size augmentation by increasing the concentration of the pore forming agent (Di-ionized water). Then, the prepared flat sheet membranes were subjected to nanofibres coating by electro-spinning. The uncoated and coated composite fabricated membranes were characterized using contact angle, liquid entry pressure of water, and scanning electron microscopy. The membranes were further tested for 6 h desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD), with a 3.5 wt.% synthetic NaClaq as the feed. In DCMD the feed liquid and permeate side temperature were maintained at 27.5 °C and 15 °C, respectively. For VMD, the feed liquid temperature was 27 °C and a vacuum of 94.8 kPa was applied on the permeate side. The maximum permeate flux achieved was 3.2 kg/m(2).h for VMD and 6.5 kg/m(2).h for DCMD. The salt rejection obtained was higher than 99.98%. The coated membranes showed a more stable flux than the uncoated membranes indicating that the double layered membranes have great potential in solving the pore wetting problem in MD.
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5, Canada.
authors.forename: Johnson E
authors.initials: JE
authors.lastname: Efome
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5, Canada. Electronic address: rana@uottawa.ca.
authors.forename: Dipak
authors.initials: D
authors.lastname: Rana
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5, Canada.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5, Canada.
authors.forename: Christopher Q
authors.initials: CQ
authors.lastname: Lan
mesh_terms: D057168:Distillation / Q000295:instrumentation* / Q000379:methods; D008567:Membranes, Artificial; D053761:Nanocomposites; D057139:Nanofibers; D011145:Polyvinyls; D012822:Silicon Dioxide / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D005465:Fluorocarbon Polymers
chemical_list: D008567:Membranes, Artificial; D011145:Polyvinyls; D012822:Silicon Dioxide; D012965:Sodium Chloride; D014867:Water; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers
keywords: Direct contact membrane distillation; Dual layer membranes; Electro-spun PVDF nano-fibres; PVDF flat sheets; Superhydrophobic SiO(2) nanoparticles; Vacuum membrane distillation