Polyamide thin film composite membranes prepared from isomeric biphenyl tetraacyl chloride and m-phenylenediamine

Three novel of isomeric tetra-functional biphenyl acid chloride: 3,3',5,5'-biphenyl tetraacyl chloride (mm-BTEC), 2,2',4,4'-biphenyl tetraacyl chloride (om-BTEC), and 2,2',5,5'-biphenyl tetraacyl chloride (op-BTEC) were synthesized, and used as new monomers for the preparation of the thin film composite (TFC) reverse osmosis (RO) membranes through interfacial polymerization with m-phenylenediamine (MPDA). The results of membrane performance test showed that membranes prepared from om-BTEC and op-BTEC had higher flux at the expanse of rejection compared with membranes prepared from mm-BTEC. The chemical composition on the active layer was characterized by attenuated total reflectance infrared (ATR-IR) and X-ray photoelectromic spectroscopy (XPS), and the results showed that the content of carboxylic acid on the membrane surface prepared from mm-BTEC are higher than these prepared from op-BTEC and om-BTEC. It seemed that all the difference containing: the membrane performance, the chemical composition on the active layer, hydrophilicity, and the surface morphology might come from the different structure and reactivity of the tetraacyl chloride monomers. (c) 2008 Elsevier B.V. All rights reserved.