Abstract
In this study, a novel photocatalytic self-cleaning nanofiltration (NF) membrane was fabricated by constructing aspartic acid-functionalized graphene quantum dots (AGQDs) into the polydopamine/polyethyleneimine (PDA/PEI) selective layer via the co-deposition method. The chemical composition, microstructure, and hydrophilicity of the prepared membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflection (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA). Meanwhile, the effects of PEI molecular weight and AGQDs concentration on NF membrane structures and separation performance were systematically investigated. The photocatalytic self-cleaning performance of the PDA/PEI/AGQDs membrane was evaluated in terms of flux recovery rate. For constructing high-performance NF membranes, it is found that the optimal molecular weight of PEI is 10,000 Da, and the optimal concentration of AGQDs is 2000 ppm. The introduction of hydrophilic AGQDs formed a more hydrophilic and dense selective layer during the co-deposition process. Compared with the PDA/PEI membrane, the engineered PDA/PEI/AGQDs NF membrane has enhanced water flux (55.5 LMH·bar−1) and higher rejection (99.7 ± 0.3% for MB). In addition, the PDA/PEI/AGQDs membrane exhibits better photocatalytic self-cleaning performance over the PDA/PEI membrane (83% vs. 69%). Therefore, this study provides a facile approach to construct a self-cleaning NF membrane.
Highlights
Introduction published maps and institutional affilThe environmental hazards of dye wastewater should not be underestimated
The acid-functionalized graphene quantum dots (AGQDs) synthesized by the bottom–up method have a dot-like structure with
The PDA/PEI/AGQDs NF membrane with self-cleaning performance was constructed by the co-deposition method
Summary
The environmental hazards of dye wastewater should not be underestimated. Membrane separation technology has the advantage of energy-saving and high efficiency, which is widely applied to treat dye wastewater. Membrane fouling is a critical issue limiting the application of membrane separation technology in dye treatment, which increases costs and reduces efficiency. Photocatalytic self-cleaning membranes provide a possible solution [1,2]. Photocatalytic self-cleaning membranes are commonly prepared by introducing nanoparticles with photocatalytic properties, which can degrade contaminants on the membrane surface by light irradiation [3,4,5,6]. The degradation of pollutants by light irradiation improves the efficiency of the membrane cleaning process
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