Influence of melamine and graphene oxide on the performance of polyamide reverse osmosis membranes for desalination

Membrane-based desalination technology stands out as a promising solution to obtain potable water by creating opportunities for water recovery. The productivity and fouling of the reverse osmosis (RO) membranes are the most common problems in desalination processes. The effect of Melamine-grafted graphene Oxide (MEL/GO) in the RO membrane preparation has a gap in existing knowledge through understanding the specific effects and synergies of these materials in membrane synthesis and desalination performance. In this study, we employed the phase inversion technique to synthesize polyamide (PA) RO membranes incorporating MEL/GO. Various membrane properties were investigated, including hydrophilicity, porosity, surface and cross-sectional morphology, permeability, and membrane performance. It was found that the optimum MEL and GO concentrations were 0.1 and 0.3% w/w, respectively. The performance of MEL, GO, and MEL/GO-incorporated membrane (Mm0.1, MG0.3, and Mm0.1/G0.3, respectively) with previously mentioned optimized concentrations resulted in enhanced performance characteristics against plain membrane (M0) free from MEL and GO. Specifically, the water flux significantly increased from 10.01 LMH/bar for M0 to 73.47 LMH/bar, 23.35 LMH/bar, and 88.21 LMH/bar for the Mm0.1, MG0.3, and Mm0.1/G0.3 membranes, respectively. Moreover, the salt rejection percentage experienced a substantial enhancement from 71.74% for the M0 to 96.57% for the Mm0.1/G0.3 membrane. This study's novelty was introducing MEL into the GO layer for the first time, enriching the amine functional group and facilitating water transportation. The results highlight the potential of these highly hydrophilic nanofillers for advanced membrane technology in desalination applications.