An Eu (III)-functionalized covalent organic framework fluorescent probe for specific detection of Flumequine based on pore restriction and antenna effect.

The overuse of quinolone antibiotics has led to a series of health and environmental issues. Herein, we combine the distinct luminescence properties of Eu3+ with the unique structure of covalent organic frameworks (COFs) to develop a precise and sensitive fluorescent probe for detecting Flumequine (Flu) in water. Eu3+ is thoroughly anchored into the channels of COFs as recognition sites, while the synthesized probe material still maintains its intact framework structure. The unique structure of COFs provides excellent support and protection for Eu3+. Therefore, COF-Eu can rapidly bind with Flu which can transfer the absorbed energy to Eu3+ through an "antenna effect", resulting in red fluorescence. Moreover, there is a good linear relationship between Flu concentration in the range of 0-30 µM, with a detection limit of 41 nM. Simultaneously, the material maintains remarkable reproducibility, with its performance remaining almost unchanged after five cycles of use. Remarkably, the probe demonstrates excellent Flu recovery rates in real samples. This study provides a viable approach for the recognition of flumequine in the environment through a customized fluorescence detection method.

Enhancing singlet oxygen production of dioxygen activation on the carbon-supported rare-earth oxide nanocluster and rare-earth single atom catalyst to remove antibiotics.

Singlet oxygen (1O2) is extensively employed in the fields of chemical, biomedical and environmental. However, it is still a challenge to produce high- concentration 1O2 by dioxygen activation. Herein, a system of carbon-supported rare-earth oxide nanocluster and single atom catalysts (named as RE2O3/RE-C, RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y) with similar morphology, structure, and physicochemical characteristic are constructed to activate dissolved oxygen (DO) to enhance 1O2 production. The catalytic activity trends and mechanisms are revealed experimentally and are also proven by theoretical analyses and calculations. The 1O2 generation activity trend is Gd2O3/Gd-C>Er2O3/Er-C>Sm2O3/Sm-C>pristine carbon (C). More than 95.0% of common antibiotics (ciprofloxacin, ofloxacin, norfloxacin and carbamazepine) can be removed in 60 min by Gd2O3/Gd-C. Density functional theory calculations indicate that Gd2O3 nanoclusters and Gd single atoms exhibit the moderate adsorption energy of ·O2- to enhance 1O2 production. This study offers a universal strategy to enhance 1O2 production in dioxygen activation for future application and reveals the natural essence of basic mechanisms of 1O2 production via rare-earth oxide nanoclusters and rare-earth single atoms.

Enhanced selective separation of vanadium(V) and chromium(VI) using the CeO2 nanorod containing oxygen vacancies.

Adsorption of vanadium from wastewater defends the environment from toxic ions and contributes to recover the valuable metal. However, it is still challenging for the separation of vanadium (V5+) and chromium (Cr6+) because of their similar properties. Herein, a kind of CeO2 nanorod containing oxygen vacancies is facilely synthesized which displays ultra-high selectivity of V5+ against various competitive ions (i.e., Fe, Mn, Cr, Ni, Cu, Zn, Ga, Cd, Ba, Pb, Mg, Be, and Co). Moreover, a large separation factor (SFV/Cr) of 114,169.14 for the selectivity of V5+ is achieved at the Cr6+/V5+ ratio of 80 with the trace amount of V5+ (~ 1 mg/L). The results show that the process of V5+ uptake is the monolayer homogeneous adsorption and is controlled by external and intraparticle diffusions. In addition, it also shows that V5+ is reduced to V3+ and V4+ and then formation of V-O complexation. This work offers a novel CeO2 nanorod material for efficient separation of V5+ and Cr6+ and also clarifies the mechanism of the V5+ adsorption on the CeO2 surface.