Triptycene based polyamide thin film composite membrane for high nanofiltration performance

A novel triptycene based polyamide (TPA) thin film composite (TFC) nanofiltration (NF) membrane was successfully synthesized via interfacial reaction between piperazine (PIP) and mixed acyl chloride on porous support film. Specifically, the mixed acyl chloride was made up of a rigid 3D-symmetric contorted monomer, triptycene-2,3,6,7,14,15-hexaacyl chloride (THC) and a conventional non-contorted planar monomer, trimesoyl chloride (TMC). Based on the contorted structure and low reactivity, the THC could enhance microporosity, hydrophilicity and surface negative charge of prepared membrane. When the mass ratio of THC equaled to 40%, an excellent NF membrane was acquired, the water permeance was 21.4 L m −2 h −1 bar −1 as well as the Na 2 SO 4 rejection was above 95%. Moreover, the TPA-40 also showed high divalent to monovalent ions selectivity and long-term operating stability. The TPA TFC NF membrane had potential application in seawater reverse osmosis (SWRO) pretreatment.