Harnessing Amine-Functionalized Fluorinated Graphene Ink for Composite Membrane Design Toward Seawater Desalination

Developing durable, high-performance membranes remains a critical challenge in direct contact membrane distillation. This study presents an ink-formulated hybrid membrane strategy that translates fluorinated graphene chemistry into a tunable ink formulation, enabling fine-tuning of interfacial composition and membrane structure. The proposed strategy integrates poly(vinylidene fluoride) with amine-functionalized fluorinated graphene (FG-Amine) through hydrogen-bonding uniformly anchored onto a nylon substrate. The combination of PVDF's intrinsic stability with the tailored chemical functionality of FG produces membranes with enhanced surface hydrophobicity, structural robustness, and resistance to wetting and fouling. The resultant membrane exhibited a high water flux of 58 Lm^-2h^-1 with 99.9% salt rejection under standard DCMD operation, further maintaining stable flux in the presence of sodium dodecyl sulfate and humic acid, confirming strong wetting resistance. Remarkably, the membrane exhibited outstanding durability by maintaining stable performance for 32 h in natural seawater without any noticeable change in flux. In addition, the membrane demonstrated prolonged stability up to 125 h when treated with salinity-enhanced seawater, confirming its excellent long-term durability. These findings demonstrate that ink-formulated hybrid membranes provide a tunable and effective platform for overcoming the challenges of wetting and fouling in MD, advancing the development of sustainable solutions for water purification.