Carbon quantum dots embedded polysulfone membranes for antibacterial performance in the process of forward osmosis

Carbon quantum dots (CQDs) are a new class of carbon nanomaterials characterised by excellent hydrophilicity, simple synthesis, environment friendliness, low cost, and low toxicity. However, the extensive application of CQDs is limited by the toxicity and high cost of their precursors. Thus, the synthesis of CQDs with green materials is desired. In this work, we proposed a green synthesis of oil palm biomass-based CQD-derived activated carbon embedded into polysulfone-selective layers to develop thin-film composite membranes, denoted as CQDs-PSF, for forward osmosis. The effects of incorporating CQDs into the PSF membrane matrix and their performance in forward osmosis were examined. The physicochemical properties of the synthesised membranes with added CQDs nanoparticles (0.5%, 0.75%, and 1.0% CQD concentration) resulted in a porous and hydrophilic membrane. The membrane with 1.0% CQD concentration exhibited the highest water flux of 226 L/m2.h, and its reverse salt flux was 59.38 mol/m2 h. The antibacterial activities of the CQDs-PSF membranes were also assayed with the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli. Results of bacterial diffusion tests of CQDs-PSF membranes indicated enhanced antibacterial activity. Overall, our findings proved that adding CQDs to PSF membrane enabled the effective enhancement of the water flux and improved antibacterial performance.