Polyamide thin film composite membrane using mixed amines of thiourea and m-phenylenediamine

Abstract

Polyamide thin film composite nanofiltration membranes were synthesized on the polyethersulfone (PES) support via the interfacial polymerization between trimesoyl chloride (TMC) and the amine mixture of m-phenylenediamine (MPD) and thiourea (TU). It is indicated that the composite membrane (PES-M5T5) prepared at the MPD/TU ratio of 5 : 5 shows higher flux and glucose rejection than the membranes prepared using the individual amine. Further the optimal membrane PES-M5T5-TEA, prepared in the presence of triethylamine (TEA) additive, shows the largest flux of 39.7 L m⁻² h⁻¹ at an operation pressure of 1.6 MPa and the glucose rejection higher than 97.0%. In combination with characterizations of ATR-IR, Raman, SEM, XPS, AFM and contact angle measurements, it is illustrated that the TEA additive can promote the IP between TMC and MPD + TU, resulting in more amount of thioamide structures generated in the top layers of PES-M5T5-TEA, which can form more free volume and consequently improve the membrane flux. In addition, the PES-M5T5-TEA membrane shows excellent chlorine resistance against immersion of 200 ppm NaClO solution more than 100 h.