Construction of self-cleaning g-C3N4/Bi2MoO6/PVDF membrane and coupling with photo-Fenton-like reaction for sustainable removal of antibiotics in wastewater.

Constructing a photocatalytic membrane and photo-Fenton reaction coupling system is a novel strategy to enhance the photocatalytic activity of the membrane and eliminate the problem of membrane contamination. Herein, a g-C3N4/Bi2MoO6/PVDF photocatalytic membrane was prepared using a tannic acid-assisted in-situ deposition method. The membrane was characterized by three advantages of photocatalytic, self-cleaning, and antibacterial properties. Under the photo-Fenton-like conditions, the membrane had superior photodegradation efficiency of 90.7% for tetracycline, one of the main antibiotic contaminants in the China's aquatic system. Moreover, the membrane had excellent photo-Fenton self-cleaning ability, its flux recovery rate was up to 96%-98% after the self-cleaning process. Photoluminescence spectra, diffuse UV-visible spectrum, transient photocurrent responses, and electrochemical AC impedance spectrum results show that the heterojunction structure formed by g-C3N4 and Bi2MoO6 could improve the separation efficiency of photogenerated electrons-hole pairs. Electron spin resonance spectroscopy confirmed the photo-electrons facilitated the formation of hydroxyl radical (·OH) in the existence of H2O2, which enhanced tetracycline degradation. Moreover, the superior photo-Fenton self-cleaning performance, which mainly relied on the active free radicals produced by the photo-Fenton-like membrane to remove dirt on the membrane surface or in the membrane pore channel. Our results may shed new light on the development of promising photocatalytic membrane systems by coupling with photo-Fenton-like processes, and facilitate their applications for wastewater treatment.

Polystyrene nanoplastics distinctly impact cadmium uptake and toxicity in Arabidopsis thaliana.

The ubiquitous presence of micro- and nanoplastics (MNPs) in soil has raised concerns regarding their potential effects on terrestrial plants. The coexistence and interactions between MNPs and heavy metals altering their phytotoxicity deserves further investigation. In this study, we explored the impacts of various concentrations of polystyrene nanoplastics (PS-NPs) and cadmium (Cd) alone or in combination on the growth and development of Arabidopsis thaliana. Additionally, we examined the effects of combined stress on the uptake and translocation of Cd within Arabidopsis thaliana. Our findings revealed several key insights: PS-NPs exhibited the capability to internalize in the maturation zone of Arabidopsis roots; the presence of Cd changed the particle size and zeta potential of PS-NPs; the presence of PS-NPs heightened Cd accumulation in the underground parts of Arabidopsis seedlings, leading to a stronger oxidative stress response in these regions; the composite stress exerted a more pronounced effect on the growth and development of Arabidopsis compared to individual stresses. Interestingly, while higher PS-NPs concentrations hindered Cd migration from roots to leaves, they also acted as carriers for Cd uptake in Arabidopsis roots. These findings shed light on the combined impacts of MNPs and heavy metals on plant physiology, offering theoretical insights to guide risk assessment strategies for MNPs and heavy metals in terrestrial ecosystems.

Dye-encapsulated Zr-based MOFs composites as a sensitive platform for ratiometric luminescent sensing of antibiotics in water.

Overuse of antibiotics posed a global threat to human health and the ecological environment. Efficient detection and control of antibiotic pollution demand novel sensory materials. Here, a dual-luminescent material FS@UIO66 was successfully synthesized by encapsulating fluorescent molecules (fluorescein sodium, FS) in UIO66 based on the in-situ encapsulation method. We found that the dual emission peaks of FS@UIO66 at 369 and 515 nm can be sensitively and synchronously quenched by tetracycline (TET). Interestingly, these two peak intensities were switched anisotropically by levofloxacin (LEV), in which the signal at 515 nm was enhanced. Photophysical analysis revealed that there may exist a competition and replenishment mechanism in the sensing processes. The ratiometric fluorescent feature was employed for rapid detection of TET and LEV, with detection limits of 0.2444 µM and 0.2808 µM for TET and LEV, respectively. The superior sensitivity, high selectivity, and excellent recyclability of FS@UIO66 in sensing TET and LEV were demonstrated in this work. In addition, TET and LEV were also successfully detected by FS@UIO66 in water from real water environment. The results indicate that FS@UIO66 composites are favorable for TET and LEV detection, presenting a great sensing platform for antibiotic detection.