title: Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation.
abstract: In this study, we fabricated a composite membrane for membrane distillation (MD) by modifying a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane with a nanocomposite coating comprising silica nanoparticles, chitosan hydrogel and fluoro-polymer. The composite membrane exhibits asymmetric wettability, with the modified surface being in-air hydrophilic and underwater oleophobic, and the unmodified surface remaining hydrophobic. By comparing the performance of the composite membrane and the pristine PVDF membrane in direct contact MD experiments using a saline emulsion with 1000 ppm crude oil (in water), we showed that the fabricated composite membrane was significantly more resistant to oil fouling compared to the pristine hydrophobic PVDF membrane. Force spectroscopy was conducted for the interaction between an oil droplet and the membrane surface using a force tensiometer. The difference between the composite membrane and the pristine PVDF membrane in their interaction with an oil droplet served to explain the difference in the fouling propensities between these two membranes observed in MD experiments. The results from this study suggest that underwater oleophobic coating can effectively mitigate oil fouling in MD operations, and that the fabricated composite membrane with asymmetric wettability can enable MD to desalinate hypersaline wastewater with high concentrations of hydrophobic contaminants.
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University , Nashville, Tennessee 37235-1831, United States.
authors.forename: Zhangxin
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University , Nashville, Tennessee 37235-1831, United States.|State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , P.O. Box 2871, Beijing 100085, PR China.
authors.forename: Deyin
authors.initials: D
authors.lastname: Hou
authors.affiliation: Department of Civil and Environmental Engineering, Vanderbilt University , Nashville, Tennessee 37235-1831, United States.|Department of Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee 37235-1831, United States.
authors.forename: Shihong
authors.initials: S
authors.lastname: Lin
mesh_terms: D057168:Distillation / Q000295:instrumentation* / Q000379:methods; D004655:Emulsions / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008567:Membranes, Artificial; D053758:Nanoparticles / Q000737:chemistry*; D010578:Petroleum; D011108:Polymers / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D062065:Wastewater / Q000737:chemistry; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*; D017155:Wettability; D005465:Fluorocarbon Polymers
chemical_list: D004655:Emulsions; D008567:Membranes, Artificial; D010578:Petroleum; D011108:Polymers; D011145:Polyvinyls; D012822:Silicon Dioxide; D062065:Wastewater; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers