Approaches to prepare tfc polyamide membranes by coating diamine during, and/or post formation of asymmetric membranes and their performances

Abstract

Thin film composite membranes were prepared by using1,3-phenylene diamine in the gelation bath as well as in coating conditions. The cross-sectional view of the membranes shows different patterns for membranes prepared in a water-bath (Mem- I) and a diamine-containing water bath (Mem-II). The thin film composite membranes prepared using a diamine bath and coating (Mem-III) had improved salt rejecting ability but low volume flux. The performances of the salt rejection follows the order Na2SO4 > NaCl > MgSO4> MgCl2, as expected. The salt separation performances of the membranes made with higher concentration of 1,3 phenylene diamine follow the order Mem-IIIb > Mem-I > Mem-IIb. For membranes made with low concentration of 1,3-phenylene diamine, the salt separation follows the same trend, (Mem-IIIa > Mem-IIa).