A THEORETICAL-ANALYSIS ON PORE-SIZE CHANGE OF POROUS CERAMIC MEMBRANES AFTER MODIFICATION

The evolution of the pore size distribution and the average pore size of porous ceramic membranes during a modification process of deposition of solids in the membrane pores are analyzed using a method based on the population balance theory. The theoretical analysis suggests that the results of modification on the pore size change of ceramic membrane are strongly determined by the initial pore size distribution of the membrane and the pore narrowing kinetics of the modification process. For a ceramic membrane having a pore size distribution with a large amount of smaller pores and a modification process with a pore size independent pore narrowing rate, the modification could result in an increase in the average pore size, unless the porosity (or permeability) of the membrane is substantially reduced. The average pore size of ceramic membranes can be reduced if the membranes have rather uniform initial pore size distribution, or if the modification process has a pore narrowing kinetics which gives a pore narrowing rate being proportional to the pore size.