Sunlight-induced uranium extraction with triazine-based carbon nitride as both photocatalyst and adsorbent

Extracting uranium from high salinity seawater at ultralow concentrations would beneficially contribute to the sustainable utilization of nuclear energy, but it poses a significant challenge. Here we report a sunlight-driven photocatalysis-assisted extraction (SUPER) method by utilizing a bifunctional carbon nitride material, CN550, which has shown about a tenfold improvement in both adsorption capacity and photocatalytic activity compared to g-C3N4. Uranyl ions could be captured on the surface of CN550, and then deposited as metastudtite nanoparticles with light illumination. Compared with the pure physicochemical adsorption (PA) method, a tenfold higher uranium extraction capacity, up to 1556 mg g−1, has been attained. Additionally, a 25 times improvement of the partition coefficient (PC), from 0.312 to 7.778 L g−1, has also been achieved. In spiked real seawater, the extraction capacity can still achieve more than 1000 mg g−1, and the SUPER method has been found to work under natural sunlight illumination as well.