COF-derived porous nitrogen-doped carbon for removal of emerging organic contaminants and efficient uranium extraction from seawater.

The development of adsorbents for efficient and highly selective seawater extraction of uranium was instrumental in fostering sustainable progress in energy and addressing the prevailing energy crisis. However, the complex background composition of the marine environment, including radionuclides, organic pollutants, and a large number of co-existing heavy metal ions, were non-negligible obstacles to the extraction of uranium from seawater. The present investigation successfully employed a self-templated approach to synthesize porous nitrogen-doped carbon (PNC) derived from COF, which exhibited tremendous potential as an adsorbent for pollutant removal in environmental treatment. LZU1@PNC not only retained the structural features of the original COF-LZU1, but also overcame the acid-base instability problem commonly found in COFs. Subsequently, the removal process of two typical water pollutants on the material was investigated using 2,4-DCP and [UO(CO)]. The results demonstrated that LZU1@PNC exhibited superior removal performance for the target pollutants compared to COF-LZU1, owing to its larger specific surface area and abundant defect structure. After six desorption-regeneration cycles, LZU1@PNC still maintained a high removal rate of the target contaminants, demonstrating the stability of this material and its excellent recyclability. In addition, based on various characterization techniques, the removal mechanism of 2,4-DCP was presumed to be mainly electrostatic attraction, hydrogen bonding, and π-π stacking interactions. Conversely, the elimination process of [UO(CO)] predominantly relied on surface complexation phenomena. The present investigation provided new perspectives and stimulated a broader study of other COF-derived carbon materials and their modifications as adsorbents for uranium extraction from seawater and other applications.