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Photocatalytic membrane Reactor

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Photocatalytic membrane Reactor

  1. 1. PHOTOCATALYTIC MEMBRANE REACTORS MR.BASITALI SADIQUE NEVAREKAR B-Tech (Chemical) 20160480 PRESENTED BY
  2. 2. INTRODUCTION
  3. 3. WHY PMRs ??? A very promising method for solving problems concerning separation of the photo-catalyst as well as products and by- products of photo- decomposition from the reaction mixture is application of photocatalytic membrane reactors (PMRs). PMRs are hybrid reactors in which photo-catalysis is coupled with a membrane processes. The membrane would play both the role of a simple barrier for the photo-catalyst and a selective barrier for the molecules to be degraded.
  4. 4. HETEROGENEOUS PHOTOCATALYSIS “Heterogeneous photocatalysis can be described as acceleration of photoreaction in the presence of catalyst”
  5. 5. External mass transfer Internal mass transfer adsorption Surface reaction Desorption Internal mass transfer External mass transfer Steps involved in heterogeneous photocatalysis
  6. 6. Figure. 1 Schematic of semiconductor excitation by band gap illumination leading to the creation of “electrons” in the conduction band and “holes” in the valance band ( Mozia 2010) MECHANISM OF PHOTOCATALYTIC OXIDATION
  7. 7. CHARACTERISTIC OF PHOTOCATALYST A Photocatalyst should possess; High activity. Resistance for poisoning. Mechanical stability and resistance to attiration. Physical and chemical stability. Inexpensive. Able to utilize not only UV light but also visible light.
  8. 8. MEMBRANE SEPARATION PROCESSES
  9. 9. Membrane techniques Pressure driven Microfiltration Ultrafiltration Nano-filtration Concentration difference driven Dialysis Pervaporation DCMD CLASSIFICATION OF MEMBRANE TECHNIQUES
  10. 10. PMRs Configurations and designs PMRs Reactors with catalyst suspended in feed solution Reactors with catalyst immobilized in/on the membrane
  11. 11. Reactors with catalyst suspended in the feed solution Irradiation of membrane module Irradiation of feed tank Irradiation of an additional reservoir PMRs with suspended TiO2
  12. 12. Figure. 3. PMR utilizing photocatalyst in suspension: irradiation of the feed tank (Mozia 2010)
  13. 13. Figure. 2. PMR utilizing photocatalyst in suspension: irradiation of the membrane module (Mozia 2010)
  14. 14. Figure. 4. PMR utilizing photocatalyst in suspension: irradiation of the additional reservoir (photoreactor) located between the feed tank and membrane module ( Mozia 2010).
  15. 15. PMRs with suspended TiO2 Reactors with catalyst suspended in feed solution With pressure driven membrane techniques Nanofiltration Ultrafiltration microfiltration With concentration driven techniques DCMD Dialysis Pervaporation
  16. 16. PMRs coupling photocatalysis with pressure-driven membrane processes Figure 5. Schematic diagram of laboratory scale slurry PMR with submerged membranes and internal (immersed) UV lamps [Fu et. al. 2006].
  17. 17. Advantages Higher photocatalytic efficiency Convenient to adjust Membrane damage could be avoided Disadvantages Higher operating cost Membrane fouling Low quality of permeate
  18. 18. PMRs with TiO2 immobilized in/on membrane
  19. 19. Figure 6. Possible types of asymmetric photocatalytic membranes .
  20. 20. Advantages No need to separate and recycle the catalyst No membrane fouling Contaminants could be decomposed either in feed or permeate Disadvantages Low photocatalytic efficiency Adjustment of catalyst loading is impossible Risk of damage of polymer membranes Necessity of membrane exchange

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