Polyamide thin-film composite membranes prepared from a novel triamine 3,5-diamino-N-(4-aminophenyl)-benzamide monomer and m-phenylenediamine

A novel triamine 3,5-diamino-N-(4-aminophenyl) benzamide (DABA) monomer was synthesized and used to prepare thin-film composite (TFC) reverse osmosis (RO) membranes with m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The membranes were characterized on both their top surfaces and cross-sections to determine their permeation properties, chemical composition, hydrophilicity, and membrane morphology. The results of the performance testing showed that the flux of membranes increased from 37.5 to 55.4 l/m2 h as the DABA concentration in amine solution was raised, while the rejection of membranes decreased slightly. Furthermore, the surface structure and chemical composition of the membranes were analyzed by X-ray photoelectronic spectroscopy (XPS), streaming potential measurement, attenuated total reflectance infrared (ATR-IR) spectroscopy, contact angle measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM) .The results revealed that, as the DABA content in amine solution increased, the membrane surface became more hydrophilic (giving rise to lower contact angles), smoother and thinner. It seemed that all the changes with regard to the membrane surface resulted from the introduction of the DABA into the amine solution.