Simultaneous sensitive detection and rapid adsorption of UO22+ based on a post-modified sp2 carbon-conjugated covalent organic framework

Abstract

As one of the most important elements in the nuclear industry, uranium has both radioactivity and chemical toxicity, which can harm human beings when released into the natural environment. It is difficult for most uranium adsorbents to maintain good stability under strong radiation and acid conditions. Therefore, it is highly desirable to develop a stable adsorbent for the rapid detection and efficient removal of uranium. Herein, we first constructed an amidoxime-functionalized luminescent sp² carbon linked covalent organic framework (TP-COF-AO), which is rich in amidoxime groups, has open 1D channels and an extraordinarily stable framework. Based on these advantages, it can reduce UO₂²⁺ from 9.25 ppm to below 10 ppb within 10 min and has a high adsorption capacity (436 mg g⁻¹). Meanwhile, the adsorption of UO₂²⁺ on TP-COF-AO results in rapid fluorescence quenching (within 2 s) with an ultra-low detection limit (8.3 nM), which is well below the maximum contamination standard in drinking water prescribed by the U.S. Environmental Protection Agency (130 nM). Moreover, it also has excellent recyclability that provides possibility for practical applications. This study indicates that the sp² carbon-conjugated COF can be used for the simultaneous detection and adsorption of UO₂²⁺ with good application prospects in environmental applications.