Other Operations Using Meso- or Macroporous Membranes

Other Operations Using Meso- or Macroporous Membranes 

A reduction of the number and dimensions of the pores on the membrane surface significantly affects the performance as evaluated in terms of gas (vapor) permeability the flux decreases. In contrast, the presence of large pores on the membrane surface enables deposits into their core as an example the deposition of CaC03 crystallites when ground water is treated. This can cause the wet ability of pores filled by deposit, or require frequent cleaning steps that in the mid-long run will themselves cause a flux decline. 

The presence of a foreign surface, specifically a polymeric membrane, decreases the work required to create critical nuclei and will increase locally the probability of nucleation with respect to other locations in the system this phenomenon is known as heterogeneous nucleation. The reduction of AG due to heterogeneous nucleation (AG ) compared to a homogeneous one (AG ° ) is related to the contact angle (0) between solution and solid substrate (Equation 4.1)  

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