ADVANCED POLYMER DESIGN AND DEVELOPMENT RESEARCH LABORATORY (APDDRL), BENGALURU
Chemical Engineering Department, Indian Institute of Technology (IIT) Bombay, Mumbai, India
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 proflometer, 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 sacrifcing 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 signifed the role of the AA in scavenging the hydrochloric acid to forestall the formation of amine salts during IP for polyamide nanocomposite membrane formation.