It is critical to recover uranium from wastewater containing U(VI) and to ensure the commercial development of nuclear related energy sources. With the rapid development of photocatalytic technology, the extraction and recovery methods of uranyl ions from contaminated areas has become clearer. However, it faces several challenges, such as low charge carrier migration and lack of active sites. In order to improve the e ciency of photocatalytic reduction of uranium, the crystallized carbon nitride (CCN) catalysts at different temperatures were successfully obtained and well characterized. The effects of catalyst dosage, pH value of solution and concentration of U( ) on the photocatalytic reactions, as well as the photoreduction mechanisms were investigated in detail. The results demonstrate that CCN can effectively remove U( ) by photocatalytic reduction, which has a great application prospect for the treatment of uranium-containing wastewater. Highlights 1. The CCN was synthesized by molten salt thermal treatment.2. The CCN had signi cantly improved charge separation and transfer performance compared with bulk CN.3. The CCN-500 had 2.5 times higher photocatalytic activities than that of bulk CN in photocatalytic reduction of U(VI).4. The CCN-500 exhibited excellent stability and reproducibility after ve cycles.
As a clean energy source, nuclear energy can gradually replace traditional fossil energy sources, and is an important means to achieve the "double carbon goal". Uranium-containing wastewater is inevitable in the development of nuclear energy. The composites MIL/CNx of MOF material MIL-100(Fe) and carbon nitride (CN) were obtained by a simple solvo-thermal method using iron nitrate, homophthalic acid and CN. The material MIL-100(Fe) with high specific surface area was compounded with CN to increase the in-plane adsorption sites, which could adsorb 30% of uranium in solution during the dark reaction. The close interfacial contact of the two materials effectively inhibited the complexation of photo-generated electrons and holes and promotes electron migration. These two synergistic effects improved their overall photocatalytic reduction capacity, which could reduce 97% of UO 2 2+ in solution in 20 min. The UO 2 2+ removal efficiency of MIL/CN 0.1 was 2.3 and 1.6 times higher than that of CN and MIL-100(Fe), respectively. In addition, MIL/CN 0.1 was stable in reducing uranium during the five cycles of the experiment.
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