Environmental Engineering Reference
In-Depth Information
TABLE 20.2
List of Commercial Membranes: Compositions and Applications
Membranes Membrane Materials Applications
Organic/polymer Cellulose regenerated D, UF, MF
Cellulose nitrate MF
Cellulose acetate GS, RO, D, UF, MF
Polyamide RO, NF, D, UF, MF
Polysulfone GS, UF, MF
Poly(ether sulfone) UF, MF
Polycarbonate GS, D, UF, MF
Poly(ether imide) UF, MF
Poly(2,6-dimethyl-1,4-phenylene oxide) GS
Polyimide GS
Poly(vinylidene luoride) UF, MF
Polytetraluoroethylene MF
Polypropylene MF
Polyacrylonitrile D, UF, MF
Poly(methyl methacrylate) D, UF
Poly(vinyl alcohol) PV
Polydimethylsiloxane PV, GS
Inorganic/ceramic Metal (Al, Zn, Ti, Si, etc.) oxide PV, MF
Metal (Al, Zn, Ti, Si, etc.) nitride PV, MF
Metal (Al, Zn, Ti, Si, etc.) carbide PV, MF
Metal (Al, Zn, Ti, Si, etc.) oxide PV, MF
SiO
2
PV, GS
Source:
L.K. Wang et al.,
Membrane Separation: Basics and Applications
, In:
Handbook of Environmental Engineering,
Membrane and Desalination Technologies
, Springer Science+Business Media, LLC, 2008.
Note:
D, dialysis, GS, gas separation, MF, microiltration, NF, nanoiltration, PV, pervaporation, RO, reverse
osmosis, UF, ultrailtration.
Membranes can be synthesized as
lat sheet
or
hollow iber
. Different preparation pro-
cesses are followed to prepare each type. To prepare lat-sheet membranes, the phase
inversion technique is used where a polymer solution e.g., polyethersulfone, is cast on
a support material (e.g., glass, polymer, metal, nonwovens) after immersing into a non-
solvent (water). Hollow-iber membranes are usually prepared by a dry-wet spinning
technique based on phase inversion.
45
Other processes that have been used include track
etching and ilm stretching.
46,47
The ideal membrane is one that is not easily susceptible
to fouling.
Membranes can further be classiied as organic (polymer based) or inorganic (ceramic
based). Polymer-based membranes are the most widely used for water treatment pur-
poses. Wang et al. have done an excellent review of the different types of commonly used
membranes and their application (Table 20.2).
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20.3.2 Characterization of Membranes
The application of membrane technologies in water treatment is met with challenges
relating to the fouling of the membranes. Membrane fouling refers to the attachment,
