Equilibrium deposition filtration technique

An alternative method used for preparing supported catalysts is the Equilibrium Deposition Filtration (EDF) technique, otherwise called equilibrium adsorption. Following this technique the support is immersed in a large volume of a dilute aqueous solution of the TMIS, ideally at fixed pH and ionic strength. Equilibration of the suspension follows for several hours under stirring. During equilibration the TMIS are deposited at the interface developed between the support surface and the aqueous solution. We call this mode of deposition interfacial deposition. In the filtration step the interfacially deposited TMIS are practically separated from the non-deposited ones. 

The efforts that can be made to restrict the amount of flux decline, i.e. to establish an equilibrium flux rate, can be split into two categories, dependent largely on the scale of operation stirred cells and crossflow filtration. The former is of use in the laboratory for small-scale separations, the latter is more appropriate for process applications. Both stirring and crossflow enq>loy the same princ le hi ear at the sur ce of the deport. Further techniques to restrict deposit thickness, minimise fouling or regenerate flux are discussed in Section. 10.7. All the main membrane arrangements are illustrated in Figure 10.4. 

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