Covalently anchoring phosphorus nitride imide on carbon nanotubes for efficient electrochemical extraction of uranium

Abstract

The electrochemical extraction technique is an emerging approach for the recovery of uranium. However, the ultra-high salinity and the coexistence of many competitive ions seriously reduce the electrochemical extraction performance of uranium. Phosphorus nitride imide (PN) demonstrates high efficiency and selectivity as a uranium adsorbent. However, its low conductivity adversely affects its electrochemical performance. In this work, the covalent grafting strategy has been employed to anchor PN onto carbon nanotubes (PN@CNT) toward efficient electrochemical extraction of uranium (EEU). CNTs not only serve as an optimal carrier for the dispersion of PN, but also establish a three-dimensional conductive network for PN, thereby facilitating the fixation and reduction of uranium ions. This ingenious structural design enables outstanding EEU performance: PN@CNT demonstrates an extremely high uranium adsorption capacity (1006.9 mg/g), excellent anti-interference and satisfactory cycle stability. PN@CNT reduced uranium-spiked groundwater from 5 mg/L to 15 μg L−1 within 12 h which meets the drinking water standard (30 μg L−1). This study offers a potential material for the EEU, while also serving as a reference for the development of electrodes in the electrochemical recovery of other heavy metals.