Toward energy efficient reverse osmosis polyamide thin-film composite membrane based on diaminotoluene

ABSTRACT Thin-film composite (TFC) membranes with polyamide (PA) as an active layer synthesized via interfacial polymerization (IP) are dominant in reverse osmosis (RO). This work reports the development of a TFC–PA–RO membrane that minimizes the energy consumption while maintaining superior membrane separation properties. The TFC–PA–RO membranes were prepared by IP of 2,6-diamino- toluene (DAT) and trimesoyl chloride (TMC) on polysulfone (PS) support. The conventional monomer, m-phenylenediamine, is replaced by a DAT monomer. These membranes were characterized by infrared spectroscopy, scanning electron microscope and contact angle measurements. It was found that the optimum preparation conditions for the TFC–PA–RO membranes included soaking DAT (1 wt%) for 2 min, TMC (0.15 wt%) for 0.5 min and curing at 75°C for 5 min. The TFC–PA–RO membrane prepared at these conditions exhibited a salt rejection of 99.54% and a permeate water flux of 11.4 L/m 2 h in 10 g/L NaCl feed solution at 18 bar. Also, the TFC–PA–RO membranes produced a salt rejection of 98.25% and a permeate water flux of 9.3 L/m 2 h at 35 bar in 35 g/L NaCl feed solution. This low operating pressure compared with the commercial membranes that operate at 55 bar for seawater desalination saves the energy consumed by the RO system to 1.29 kWh/m 3 .