Realizing Direct Uranium Extraction from Seawater Using a Carboxyl-g-C3N4/CdS Hydrogel.

The photocatalytic U(VI) reduction is regarded as an effective strategy for recovering uranium. However, its application in seawater uranium extraction poses challenges due to limited reactivity in the presence of carbonate and under atmospheric conditions. In the present study, a photoactive hydrogel made of carboxyl-functionalized g-C3N4/CdS (CCN/CdS) is designed for extracting uranium. The carboxyl groups on g-C3N4 enhance the affinity toward uranyl ions while CdS facilitates the activation of dissolved oxygen. Under atmospheric conditions, the prepared hydrogel catalyst achieves over 80% reduction rate of 0.1 mM U(VI) within 150 min in the presence of carbonate, without the assistance of any electron donors. During the photocatalytic process, U(VI) is reduced to form UO2+x. The hydrogel catalyst exhibits a high uranium extraction capacity of >434.5 mg g⁻1 and the products can be effectively eluted using a 0.1 M NaCO3 solution. Furthermore, this hydrogel catalyst offers excellent stability, good recyclability, outstanding antifouling activity, and ease of separation, all of which are desirable for seawater uranium extraction. Finally, the test in real seawater demonstrates the successful extraction of uranium from seawater using the prepared hydrogel catalyst.

A review on photocatalytic attribution and process of pyrolytic biochar in environment.

Biochar has attracted significant attention due to its excellent environmental benefits and extensive applications. Recently, a consensus has been accepted that biochar can act as a photocatalyst and trigger effective photocatalytic reactions in the environment, which is important to energy conversion and the cycle of elements. However, its photocatalytic processes and the corresponding environmental impacts need to receive more and due attention. In this review, we provide a comprehensive summary of the underlying correlations among the pyrolytic evolution of biomass, the structure characteristic of biochar, and the resultant photocatalytic performance. Moreover, the photocatalytic processes and the influence of environmental factors were elaborately investigated on biochar. Finally, future tendencies and challenges in the photocatalysis of biochar have been prospected in the environmental field. This review has offered innovative insights into the photocatalytic essential of biochar and highly enhanced the understanding of its environmental impact.