The polyamide thin-film composite (TFC) membranes synthesized via interfacial polymerization (IP) are commonly used in membrane technologies such as nanofiltration (NF) and reverse osmosis (RO) membrane. The polyamide selective layer is the key factor to success of the NF because of their high selectivity and permeability. Even though polyamides are effective, a lot of effort is being made in developing new blend monomers to achieve a better membrane performance such as high water flux, high salts and organic dyes rejection and reduce of fouling on membrane surface. This talk presents the development of newly hydrophilic polyamide (PA) thin film which are synthesized by using two diamines on the surface functionalized of PVDF hollow fiber membranes. The blended diamine solutions were investigated using the conventional aromatic (m-phenylenediamine, MPD) and various concentration of aliphatic diamine monomers. The result showed that incorporating aliphatic diamine units into the polyamide network substantially increased hydrophilic (water contact angle 19-50°) comparing to conventional MPD (water contact angle 79°). By comparing the roughness within the group of hydrophilic polyamides, at 2 wt.% of longer chain aliphatic polyamides showed a slightly lower roughness than that of 1 wt.% of shorter chain counterpart, which are confirmed with AFM surface analysis. The effect of various concentrations of aliphatic diamine monomer on the mechanical properties was investigated by an indentation test method. At 1-2 wt.% hydrophilic polyamides, the hardness was decreased from 0.023-0.025 GPa to 0.012-0.016 GPa for shorter chain aliphatic polyamides and longer chain aliphatic polyamides, respectively. The elastic modulus of longer chain aliphatic polyamides was increased by 39 % due to the influence of an internal molecular packing of polyamides and the flexibility of the polymer chains. The results revealed that hydrophilic polyamide also showed a high water flux which is 3 times higher than that of hydrophobic polyamide and was able to reject mono and divalent cations and aninos ranging from 40%-90%. Based on these results, the hydrophilic polyamides can be considered to be promising membrane for NF.

Development of hydrophilic nanofiltration membrane for water purification

2019 Fall National Meeting

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