A novel semi-aromatic polyamide TFC reverse osmosis membrane fabricated from a dendritic molecule of trimesoylamidoamine through a two-step amine-immersion mode†
In this work, a novel semi-aromatic polyamide RO membrane was fabricated by using a new self-made dendritic molecule trimesoylamidoamine (TMAAM) as a key functional amine monomer that combined 1,3-diamino-2-propanol (DAP) to react with trimesoyl chloride (TMC) through interfacial polymerization technology. By adjusting the TMAAM concentration and amine-immersion mode, this new TMAAM-based semi-aromatic polyamide RO membrane exhibits simultaneously improved water permeability, antifouling and chlorine-tolerant properties. The introduced TMAAM units in polyamide chains can enhance the TMAAM-based membrane's water flux due to its dendritic structure as well as rich hydrophilic groups, and the DAP–TMAAM–TMC membrane prepared via the new two-step amine-immersion mode has 1.9 times more water flux without loss of salt rejection than the pristine DAP–TMC membrane and also shows higher water flux than the hand-cast conventional aromatic polyamide MPD–TMC membrane, respectively. At the same time, the regularly distributed hydroxyl groups and aliphatic amide bonds in TMAAM units contribute to the improved hydrophilicity and chlorine-tolerant property of the resultant DAP–TMAAM–TMC membrane, respectively. It is also demonstrated that the new two-step amine-immersion mode leads to a much smoother surface which endows the resultant DAP–TMAAM–TMC membrane with a favorable antifouling ability. This research provides us with a promising functional amine monomer and a new membrane formation method to fabricate a high performance RO membrane.