EFFECT OF THE CASTING SOLUTION COMPOSITION ON PORE SIZE AND PORE SIZE DISTRIBUTION OF RESULTING AROMATIC POLYAMIDE MEMBRANES

Abstract
The control of average pore size and pore size distribution on the surface of reverse osmosis (RO) membranes of aromatic polyamide (PA) material was studied by properly adjusting the composition of casting solutions which consisted of polymer—solvent, dimethylacetamide (DMA) —nonsolvent (swelling agent), calcium chloride. The average size and the distribution of the network and aggregate. pores were related to the size of the supermolecular polymer aggregates present in the casting solutions, which was changed by changing the concentration of polymer and nonsolvent/polymer ratio in the casting solutions. It has been found that the nonsolvent swelling agent additive plays a dual function of increasing the aggregate size and inducing the flux of gelation media into the film during the gelation step in the membrane making process.

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