Hydrophilic Fe(III)-Phytate Functionalized Graphene Oxide Nanosheets Incorporated Polyamide Nanofiltration Membranes for Enhancing Separation and Anti-fouling Performance

Nanofiltration (NF) membrane technology has emerged as a promising part of desalination techniques due to its high rejection to divalent ions with a low requirement of energy. Polyamide (PA) membranes, as widely used NF membranes, still suffer from critical limitations. One limitation is the dense polymeric network, which imposes a significant mass transfer resistance. Another limitation is its insufficient hydrophilicity, which causes foulant adsorption through hydrophobic interactions, leading to low water permeance and fouling. Herein, the hydrophilic graphene oxide (hGO) nanosheets functionalized with Fe(III)–phytate complexes were integrated into PA membranes during interfacial polymerization, resulting in the formation of a composite membrane with enhanced hydrophilicity and a relatively loose structure, thereby improving both separation efficiency and antifouling performance. Moreover, the enlarged interlayer channels between hGO nanosheets provide additional fast-transport pathways, which contributes conjointly to the improvement of water permeance. The optimized PA-hGO membrane displayed about 1.5-fold higher water permeance compared to the pristine PA membrane while successfully holding a Na2SO4 rejection of over 98%.