Engineering hollow fiber membranes with poly-m-aminophenol functionalized graphitic carbon nitride for efficient water purification

Water pollution caused by industrialization poses a great threat to the living organisms mainly due to the release of dye wastewater and pollutants into the water bodies. Ingestion of such polluted water has detrimental effects on living organisms. To address the issue, the present study focuses on the synthesis of poly-m-aminophenol functionalized graphitic carbon nitride (FCNs) using inexpensive graphitic carbon nitride and m-aminophenol. The synthesized FCNs were characterized with FTIR, XPS, XRD, TGA, DTA, Zeta potential, Particle size, TEM and BET analysis. These FCNs were further incorporated into the hollow fiber membrane and subsequently analyzed using SEM, AFM, Zeta potential, Hydrophilicity, and performance studies. Among the fabricated membranes, the optimized CN-AP 50 membrane exhibited enhanced an average water permeability of 150 Lm^-2 h⁻¹ bar ⁻¹ and a Flux recovery ratio of 49.9 % with 11.9 % of reversible fouling. Furthermore, the membrane also displayed excellent dye rejection capacity of >99 % for Congo red, >98 % for Reactive black 5, and 86 % for Reactive orange 16. Additionally, it showed impressive heavy metal ion removal capability of 99 % for lead ions and 60 % for mercury ions in the presence of humic acid. These enhanced rejection and water permeability are due to the various effects such as improved hydrophilicity, electrostatic interaction between functional groups, π-π interaction with the dye molecules. These effects also modify the membrane morphology thereby enhancing size exclusion and adsorption capabilities. The present study discusses a strategy for incorporating poly-m-aminophenol functionalized graphitic carbon nitride as an additive in membrane fabrication. The functionalized material improves water permeability, antifouling performance, and membrane selectivity, thus offering a scalable route for advanced wastewater treatment technologies.