Sequestration process and mechanism of U(VI) on montmorillonite-aspergillus niger composite.

Sci Total Environ

Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Petroleum Resources Exploration and Evaluation, Gansu Province, Lanzhou 730000, China; Key Laboratory of Strategic Mineral Resources of the Upper Yellow River, Ministry of Natural Resources, Lanzhou 730046, China. Electronic address:

Published: December 2024

The existence state and spatiotemporal evolution process of uranium in mineral-microbe complex systems are important factors that constrain its ecotoxicity. This study investigated the sequestration of U(VI) by montmorillonite-Aspergillus niger (MTA) composite using bioassay and spectroscopies approaches. The results demonstrate that the sequestration process and mechanism of U(VI) on MTA differ substantially from those of individual components. Under neutral conditions, the sorption of U(VI) decreased from 92.4 ± 4.6 % on MT to 73.2 ± 2.4 % on MTA4 and 74.9 ± 6.3 % on MTA10, respectively, while the stability of U(VI) species on MTA increased obviously compared to MT. In the case of MTA formed over 4 days (MTA4), the biosorption effect of A. niger hyphae dominated the sequestration of U(VI). In contrast, for MTA formed over 10 days (MTA10), the interactions between MT and A. niger became more pronounced, and the hyphae of Aspergillus niger played a pivotal role in U(VI) sequestration, immobilizing U(VI) through complexation with organic ligands and bioreduction reactions. The high expandability of MT facilitated the penetration of extracellular polymeric substances (EPS) from A. niger into its interlayer of MT, enhancing U(VI) complexation and reduction. These processes significantly contributed to the effective sequestration of U(VI) by the MTA composite.

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http://dx.doi.org/10.1016/j.scitotenv.2024.177952DOI Listing

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