Pore blocking schematic mechanism

Figure 11, Schematic mechanisms of pore filling and pore blocking by liquid impregnation and by chemical vapor deposition (26).

FIGURE 8.2 Fouling schematics for different mechanisms, (a) Pore construction, (h) pore blocking, and (c) cake formation. 

Figure 14.5 Schematic mechanisms of pore filling and pore blocking by liquid impregnation and by chemical vapor deposition. Source Reprinted with permission from Kollensky WV, Chem Phys Carbon, 9, 173, 1973. Copyright 1973, CRC Press, Boca Raton, Florida.

The SSF membranes are produced by carbonization of polyvinyhdene chloride (PVDC) [29]. They contain nanopores (5—7 A in diameters) which allow all of the molecules of the feed gas mixture to enter the pore structure. However, the larger (higher polarizability) and the more polar molecules are selectively adsorbed on the pore walls at the high-pressure side. Then they selectively diffuse on the pore surface to the low-pressure side, where they desorb into the gas phase. The adsorbed molecules effectively block the transport of the smaller molecules through the void space within the pores, if any. Figure 22.7(b) schematically depicts the transport mechanism through an SSF membrane. 

The somewhat complicated fiinction, Eq (165), is still only a single ion matrix element. The actual mechanism envisaged for the the larger ion transfer is more complicated for the reason that the membrane pore is closed in the normal state by the blocking ion and the whole process involves two or more ions. The process can be represented schematically as... 

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