Boron removal with modified polyamide RO modules by cross‐linked glutaric dialdehyde grafting

Abstract

AbstractBACKGROUNDReverse osmosis (RO) plays an increasingly important role in boron removal. In this study, novel polyamide RO membranes and modules with high boron rejection were fabricated by cross‐linked glutaric dialdehyde (GA) grafting. To evaluate the influence of GA grafting on membrane materials, the surface properties before and after modification were analyzed.RESULTSThe results showed that the membrane morphology changed distinctly after GA modification. All modified membranes became more hydrophilic as the water contact angle decreased from 60° to 35°. The zeta potential of RO membrane surface increased from −6.23 mV to 17.27 mV, which indicated that the surface charge altered from negative to positive. The rejection of boron increased from 76.65% to 90.14% and the boron permeability coefficient decreased from 3.71 to 0.79. Furthermore, the rejection of boron for modified module was >90% over a 5–22 ppm range of boron concentration. The rejection of boron also stabilized at ≈90% beyond 3000 min.CONCLUSIONThe modified RO membrane modules with high boron rejection and acceptable flux could be used in boron removal. The approach in this study can improve the separation properties of boron for commercially available modules without disassembling. © 2020 Society of Chemical Industry (SCI)