Performance and Structure of Thin Film Composite Reverse Osmosis Membranes Prepared by Interfacial Polymerization in the Presence of Acid Acceptor

During interfacial polymerization (IP) reaction between m-phenylenediamine (MPDA) and trimesoyl chloride (TMC), a by-product, i.e. hydrochloric acid can produce. This produced acid diffuses back in aqueous phase and protonates MPDA and reduces its reactivity that results in lowering of polymer yield and performance of membrane. Further, for getting consistency in reverse osmosis membranes formation, different acid acceptors (AAs) can investigate in the IP to form polyamide-made barrier layer formation. The main objective was to scavenge hydrochloric acid produced during IP and to fabricate membrane having high flux and salt rejection ability. AAs (of varying concentrations) tested were triethylamine-camphorsulfonic acid (TEACSA), triphenyl phosphate (TPP), sodium hydroxide (SH) and trisoduim phosphate (TSP) for studying structure and performance of membranes. The membrane samples were then characterized using surface profilometer, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy, atomic force microscopy (AFM), and contact angle goniometer. Results indicated that the addition of organic AA improves water permeability of the membranes without sacrificing salt rejection. The optimum membranes were prepared with AA concentrations of 3.4, 0.15, 0.02 and 0.19 wt.% for TEACSA, TPP, SH and TSP respectively. Membranes produced in presence of AA had higher surface area difference, hydrophilicity and water flux. Additionally, compare to inorganic AAs, the use of organic AA produced membrane with thicker polyamide layer and higher cross-link density. These induced changes in the physicochemical features of the prepared membranes also signified the role of the AA in scavenging the hydrochloric acid to forestall the formation of amine salts during IP for polyamide nanocomposite membrane formation © 2019 MPRL.