Green carbon dots-embedded polymeric membranes for simultaneous photocatalytic dye degradation and antibacterial activity

Abstract

This work presents the development of multifunctional polymeric membranes incorporating green-synthesized carbon dots (CDs) that simultaneously enable the photodegradation of methylene blue (MB) and exhibit antibacterial activity. CDs containing nitrogen and oxygen heteroatoms were synthesized from natural precursors and embedded into hydrophilic (PVA/PAA) and hydrophobic (PPSU) polymeric matrices via a phase-inversion method. The physicochemical properties of the membranes were characterized by FTIR and SEM, revealing changes in chemical interactions, morphology, and porosity induced by CD incorporation. The resulting nanostructured membranes exhibited enhanced photocatalytic performance under light irradiation, achieving rapid dye removal within the first 24 h and promoting advanced oxidation of MB, as supported by chemical oxygen demand (COD) analysis. In addition, the membranes demonstrated strong antibacterial activity against representative Gram-positive and Gram-negative bacteria, with high inhibition efficiency maintained under simultaneous photocatalytic conditions. The improved performance is attributed to the photoactive nature of CDs, their ability to generate reactive oxygen species, and their interactions with the polymer matrices. Overall, this study demonstrates that green-synthesized CD-based membranes represent an effective and sustainable strategy for integrated pollutant degradation and microbial control in water treatment applications.