Oxygen vacancies-rich bimetallic Zr/Co-UiO-66 materials for bifunctional adsorption-photodegradation of tetracycline antibiotics in water

Abstract

As broad-spectrum antibiotics, tetracycline antibiotics (TCs) have been extensively utilized in aquaculture and agricultural production processes. However, the misuse of TCs has led to severe ecological pollution and posed significant risks to human health. The adsorption-photocatalytic synergistic technology based on metal-organic framework materials (MOFs) is considered a highly promising strategy for the efficient removal of organic pollutants. In this study, a bimetallic Zr/Co-UiO-66 framework material with dual adsorption and photocatalytic functionalities was synthesized, targeting the removal of TCs from water. This material exhibited a high specific surface area and abundant oxygen vacancies (OVs), which facilitated rapid adsorption of contaminants and efficient separation and transfer of the carriers. Compared to the monometallic framework Zr-UiO-66, the bimetallic framework demonstrated superior adsorption (5.13-fold) and photocatalytic efficiency (2.21-fold). The adsorption behavior of oxytetracycline (OTC) by Zr/Co-UiO-66 fitted well with the Freundlich isotherm model and followed the pseudo-second-order kinetic model. The synergistic effect of adsorption and photocatalysis (1.72-fold increase in kinetic rate) was verified by comparison with sequential adsorption-degradation processes. The photocatalytic degradation mechanism for OTC was elucidated, and the degradation intermediates and five pathways were identified through LC-MS analysis. The bimetallic Zr/Co-UiO-66 achieved high degradation efficiency (90.7 %–97.9 %) for TCs and exhibited broad-spectrum activity, good long-term operational stability and recyclability. This study proposes a robust and referential method for the development of multi-functionalized framework materials that facilitates the efficient removal of pollutants from environmental samples.