To overcome membrane permeation selectivity defects and mitigate membrane fouling, a novel nanocomposite, UiO-66-NH 2 /g-C 3 N 5 (UNCN), was designed and synthesized. Notably, this composite overcomes the inherent limitations of UiO-66-NH 2 (limited visible light absorption) and g-C 3 N 5 (low specific surface area). The optimal composite ratio was determined to be 3:7 through systematic optimization. The UNCN-3:7 nanocomposite was then embedded into the polyamide selective layer on polysulfone via in situ interfacial polymerization under optimal conditions, resulting in a thin film nanocomposite (TFN) Nanofiltration membrane. Characterization revealed that the UNCN-3:7 Nanocomposites were uniformly distributed within the polyamide (PA) matrix. The resulting TFN Nanofiltration membrane possessed an ultrathin, positively charged selective layer with enhanced hydrophilicity, evidenced by a reduction in water contact angle from 60.3° to 47.3°. It exhibited a 43% increase in pure water permeability compared to the unmodified thin film composite (TFC) membrane (52.7 vs. 36.9 L·m −2 ·h −1 ·bar −1 ), while maintaining an excellent Na 2 SO 4 retention rate (> 96%). Furthermore, the membrane demonstrated excellent photocatalytic degradation performance, superior anti-fouling properties (flux recovery rate > 92%), and stable long-term operation. These results indicate that the construction of the novel UNCN nanocomposite Nanofiltration membrane presents an effective strategy to address membrane fouling issues.
The proper design of photocatalysts is essential to improving photocatalytic decomposition of water and degradation of pollutants. In this work, we used nitrogen-rich carbon nitride with high electronic properties combined with CdS-DETA to generate CdS-DETA@g-C 3 N 5 composite, and diethylenetriamine (DETA) was used to enhance the band bending to enable the excellent photocatalytic performance of the photocatalyst. The hydrogen evolution rate (14.23 mmol/(g·h)) of the CdS-DETA@g-C 3 N 5 composite is 7.1, 7.5, and 4.5 times higher than that of g-C 3 N 5 (2.03 mmol/(g·h)), 20CSCN5 (1.89 mmol/(g·h)), and CdS-DETA (3.17 mmol/(g·h)), and the OFLX degradation rate (95.6 %) is 3.4 and 1.5 times higher than that of g-C 3 N 5 and CdS-DETA, respectively. These performance enhancements result from the enhancement of energy band bending, the construction of a built-in electric field (IEF), and the retention of high redox carriers. This work provides new insights into the design of nitrogen-rich carbon nitride-based photocatalyst for efficient photocatalytic degradation and hydrogen precipitation activity.
Graphitic carbon nitride (g-C 3 N 4 ) has been shown as a promising visible-light photosensitizer for photodynamic therapy (PDT) application. Nevertheless, its therapeutic efficiency is limited by the low efficiency of visible-light utilization. To overcome this issue, 3-amino-1,2,4-triazole-derived graphitic carbon nitride nanosheets (g-C 3 N 5 NSs) are prepared for PDT application. The addition of nitrogen-rich triazole group into the g-C 3 N 4 motif significantly makes the light absorption of g-C 3 N 5 NSs red-shift with the band gap down to 1.95 eV, corresponding to a absorption edge at a wavelength of 636 nm. g-C 3 N 5 NSs generate superoxide anion radicals (O 2 •– ) and singlet oxygen ( 1 O 2 ) under the irradiation of a low-intensity white light emitting diode. Owing to the high efficiency of visible-light utilization, g-C 3 N 5 NSs show about 9.5 fold photocatalytic activity of g-C 3 N 4 NSs. In vitro anticancer studies based on the results of CCK-8 assay, Calcein-AM/PI cell-survival assay and photo-induced intracellular ROS level analysis in living HeLa cells demonstrate the potential of g-C 3 N 5 NSs as a low-toxic and biocompatible high-efficient photosensitizer for PDT.
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