# US 9,751,052 B2 · Triple layer hydrophobic-hydrophilic membrane for membrane distillation applications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,052 B2 - Document ID: US9751052B2 - Status: Granted - Kind: B2 - Application number: 14/357,334 - Filed: 2011-11-17 - Published: 2014-11-06 - Granted: 2017-09-05 - Earliest claimed: 2011-11-17 - Assignees: Ngee Ann Polytechnic - Applicants: Gurdev Singh; James Antony Prince - Inventors: Gurdev Singh; James Antony Prince - Web page: https://patentgrep.com/patent/US9751052B2 ## CPC - B01D 71/56: Polyamides, e.g. polyester-amides - B01D 61/364: {Membrane distillation} - B01D 67/00042: {by deposition of fibres, nanofibres or nanofibrils} - B01D 69/02: characterised by their properties - B01D 69/12: Composite membranes; Ultra-thin membranes - B01D 69/127: {using electrical discharge or plasma-polymerisation} - B01D 71/06: Organic material - B01D 71/34: Polyvinylidene fluoride - B01D 71/36: Polytetrafluoroethylene - B01D 71/701: {Polydimethylsiloxane} - B32B 3/26: characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids {(foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205); characterised by an apertured layer} - B01D 2319/06: Use of membranes of different materials or properties within one module - B01D 2323/39: Electrospinning - B01D 2325/0283: Pore size - B01D 2325/36: Hydrophilic membranes - B01D 2325/38: Hydrophobic membranes - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM ## Abstract This invention relates to a triple layer composite nanofiber membrane for Membrane Distillation (MD) applications. The triple layer membrane has an extremely hydrophobic nanofiber layer, a hydrophobic microporous middle layer and a hydrophilic backing layer for MD applications. ## Claims ### Claim 1 A multi-layered structure for membrane distillation comprising: a microporous layer having a first surface and a second surface; a hydrophobic electrospun nanofiber layer disposed on said first surface of said microporous layer, wherein said electrospun nanofiber layer has a larger contact angle than the contact angle of said microporous layer to prevent wetting of said microporous layer, and an outer surface of said electrospun nanofiber layer for adjoining a distilland, wherein said distilland comprises liquid for distillation, and said electrospun nanofiber layer acts as a liquid-vapor interface for withstanding a minimum predefined liquid entry pressure of distilland; and a hydrophilic backing layer disposed on said second surface of said microporous layer, wherein said backing layer has a smaller contact angle than the contact angle of said microporous layer to increase absorption of water vapor at said backing layer, and an outer surface of said backing layer for adjoining a distillate area for receiving a distillate wherein said distillate comprises liquid condensing from vapor passing through said multi-layered structure. ### Claim 2 (depends on 1) The multi-layered structure of claim 1 wherein said liquid-vapor interface withstands liquid entry pressures of said distilland of at least 350 kilopascals. ### Claim 3 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer has porosity between 70% and 90%, to trap air. ### Claim 4 (depends on 3) The multi-layered structure of claim 3 wherein said electrospun nanofiber layer has an average pore size between 0.05 μm and 5 μm. ### Claim 5 (depends on 1) The multi-layered structure of claim 1 wherein said microporous layer has an average pore size between 0.01 μm and 1 μm. ### Claim 6 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer is heat pressed to said microporous layer. ### Claim 7 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer is glued to said microporous layer. ### Claim 8 (depends on 6) The multi-layered structure of claim 6 wherein said backing layer is solvent bound to said microporous layer. ### Claim 9 (depends on 6) The multi-layered structure of claim 6 wherein said backing layer is heat pressed to said microporous layer. ### Claim 10 (depends on 7) The multi-layered structure of claim 7 wherein said backing layer is glued to said microporous layer. ### Claim 11 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer comprises nanofibers with a diameter between 10 nm and 800 nm. ### Claim 12 (depends on 11) The multi-layered structure of claim 11 wherein said nanofibers are spun with an air gap distance between 50 mm and 200 mm. ### Claim 13 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer further comprises hydrophobic additives applied to said nanofiber. ### Claim 14 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise surface modifying agents. ### Claim 15 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise clay nanoparticles. ### Claim 16 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise carbon nanoparticles. ### Claim 17 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise carbon nanotubes. ### Claim 18 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise fullerenes. ### Claim 19 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise polystyrene. ### Claim 20 (depends on 13) The multi-layered structure of claim 13 wherein said hydrophobic additives comprise Polydimethylsiloxane. ### Claim 21 (depends on 1) The multi-layered structure of claim 1 wherein said microporous layer has a contact angle between 70° and 130°. ### Claim 22 (depends on 21) The multi-layered structure of claim 21 wherein said electrospun nanofiber layer has a contact angle between 140° and 160°. ### Claim 23 (depends on 21) The multi-layered structure of claim 21 wherein said backing layer has a contact angle between 0° and 40°. ### Claim 24 (depends on 1) The multi-layered structure of claim 1 wherein said microporous layer has a thickness between 50 μm and 150 μm. ### Claim 25 (depends on 24) The multi-layered structure of claim 24 wherein said electrospun nanofiber layer has a thickness between 10 μm and 200 μm. ### Claim 26 (depends on 24) The multi-layered structure of claim 24 wherein said backing layer has a thickness between 50 μm and 100 μm. ### Claim 27 (depends on 1) The multi-layered structure of claim 1 wherein said electrospun nanofiber layer is electrospun from a liquid polymer. ### Claim 28 (depends on 27) The multi-layered structure of claim 27 wherein said liquid polymer further comprises Polyvinylidene fluoride. ### Claim 29 (depends on 1) The multi-layered structure of claim 1 wherein said backing layer comprises melt blown fiber. ### Claim 30 (depends on 29) The multi-layered structure of claim 29 wherein said melt blown fiber comprises Polyethylene terephthalate. ### Claim 31 (depends on 29) The multi-layered structure of claim 29 wherein said melt blown fiber comprises Polyethylene. ### Claim 32 (depends on 29) The multi-layered structure of claim 29 wherein said melt blown fiber comprises Polytetrafluoroethylene. ### Claim 33 (depends on 1) The multi-layered structure of claim 1 wherein said microporous layer further comprises polydimethylsiloxane (PDMS). ### Claim 34 (depends on 33) The multi-layered structure of claim 33 wherein said microporous layer comprises a PDMS concentration between 0 wt % and 6 wt %. ### Claim 35 (depends on 33) The multi-layered structure of claim 33 wherein said microporous layer comprises a PDMS concentration of 6 wt %. ### Claim 36 (depends on 35) The multi-layered structure of claim 35 wherein said multi-layered structure is able to withstand a LEP of at least 730 kilopascals.