Membrane and Desalination Technologies - TCE Moodle Website

242 L.K. Wang et al.
Cl –
OH –
HCl
NaOH
C A CA C A CA C A
H +
Na +
NaCl
dil HCl
in temperature, pressure, and pH, especially under cleaning and sanitizing conditions; (b)
membrane –solute interactions, which affect the rate of fouling, cleaning, yields, and rejection
of individual feed substances, and (c) the acceptability of the membrane as a contact
material for the final product, which essentially implies using membrane materials that are
inert and do not leach out any toxic substances from the membrane into the final product. In
this regard, there are new generations of membranes, made of expensive inorganic inert
materials, such as ceramics, stainless steel, carbon–zirconia, etc.
Cl –
C : Cation-exchange membrane
A : Anion-exchange membrane
CA : bipolar membrane
H +
dil NaOH
OH –
Na +
Fig. 6.3. Separation capabilities of ED and EDR.
Table 6.1
List of applied pressure for typical membrane filtration process
Membrane process Pressure (atm)
Microfiltration (crossflow) 0.7–1.7
Ultrafiltration 1.7–10.2
Nanofiltration 6.8–13.6
Reverse osmosis 20.4–40.8