Merits of using cellulose triacetate as a substrate in producing thin-film composite nanofiltration polyamide membranes with ultra-high performance

Choosing the property of the supporting membrane is crucial in preparing high performing nanofiltration membranes through interfacial polymerization. In this study, an oxygen rich membrane – cellulose triacetate (CTA) – was used to fabricate the support membrane. Polyamide was deposited onto the CTA support using interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC). The concentration of the monomers was optimized. Furthermore, the polyamide layer prepared on CTA support exhibited higher separation efficiency for sodium sulfates and dyes compared to using traditional polysulfone (PSf) support. The oxygen groups of CTA facilitate better adsorption of amines on the surface; thus, using low concentration of PIP could still provide a defect-free polyamide layer. Utilizing the optimum condition, the polyamide/CTA membrane delivered a high pure water flux (operating at 6 bar) of 179.5 L/m2h with the following rejections: Na2SO4 = 98.4%; MgSO4 = 60.3%; MgCl2 = 15.0%; NaCl = 3.7%; Rose Bengal = 95.5%; Brilliant Blue R = 99.9%; Amido Black 10B = 90.6%; Orange G = 67.3%. Moreover, the polyamide/CTA membrane had excellent stability at a wide range operating conditions. © 2020 Taiwan Institute of Chemical Engineer