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Liquid Membranes

Liquid Membranes. Phase 2. Membrane. Phase 1. Immobilised (ILM) or Supported (SLM). Emulsion (ELM). Organic liquid & surfactant. Receiving phase. Porous support. liquid. Types of LM. Volumetric or Bulk (VLM). A. A. A. AC. A. Facilitated Transport. Diffusive transport.

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Liquid Membranes

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  1. Liquid Membranes Phase 2 Membrane Phase 1

  2. Immobilised (ILM) or Supported (SLM) Emulsion (ELM) Organic liquid & surfactant Receiving phase Porous support liquid Types of LM • Volumetric or Bulk (VLM)

  3. A A A AC A Facilitated Transport Diffusive transport Facilitated transport

  4. Carrier Mediated Transport Mobile Carrier Fixed Carrier Diffusivities (cm2/s) Mobile Gel Fixed 10-5-10-7 10-6-10-8 >10-7

  5. A A AC B AC A BC B A Types of FT… Uncoupled Reaction A+C<=>AC Coupled

  6. A A AC B B B A AC B BC B A Coupled configurations Counter coupled transport Reaction A+CB<=>AC+B Co-coupled transport

  7. FT Mechanism Source phase LM Strip phase M+ M+ HC MC H+ H+ 1) Carrier reacts with solute 2) The complexed carrier diffuses across the membrane 3) Because the adjacent solution is dilute, the solute carrier reaction is reversed, releasing solute 4) The carrier returns across the membrane

  8. FT: fast reaction case • Carrier-solute Complex reaction: k...distribution coefficient Flux of solute A: K...equilibrium constant Flux due to diffusion Flux due to complexation

  9. Limiting cases Diffusion of the complex Total Flux Fickean Flux CA,0>>CAC,0 Intermediate Region CAC,0>>CA,0 Fickean diffusion Damkolher number

  10. SLM Geometry Planar Flat Laboratory Industry Hollow Fiber Spiral wound

  11. Flat Sheet Hollow Fiber Comparing Small leaks do not seriously affect the performance If the membrane liquid is contaminated, it can be easily be replenished. The pressure drop in fibre bundles is larger Feed and strip solutions mix directly and the integrity of separation is lost. Can be fabricated easily in the lab

  12. SLM Problems evaporation disolution large Dp Solvent loss Irreversible side reactions Solvent condensation Carrier loss Liquid flows

  13. Stabilization techniques

  14. Classical Fields of Applications • Facilitated transport of gases • Oxigen • Carbon Dioxide • Carbon Monoxide • Hydrogen Sulfide • Olefins • Nitric Oxide • Sensor development

  15. ... more Applications • Immobilized Liquid Membranes • Metal ion separations • Control of heavy metals pollutants • Recovery of: copper, uranium and cobalt • Separation of fermentation products • Acetic and citric acid

  16. ...and more • Emulsion Liquid Membranes • Metal ion extraction • Amino acid extraction • Removal of species without chemical carriers

  17. Hollow fiber membrane-based enzyme-facilitated separation

  18. Addition of LM components Recovered components of the LM Emulsifier Fresh emulsion Wastewater Emulsion reflux Inner Phase Settler Purified Water Mixer Purification using ELM Inner Phase

  19. Balance of using LM • Benefits • High fluxes • Very selective separations • Ions can be concentrated • Expensive extractants can be used • Major Limitations • Rupture • Long term stability

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