Uranium adsorption and subsequent re-oxidation under aerobic conditions by Leifsonia sp. - Coated biochar as green trapping agent
| Autor: | Qi Fang, Mi Li, Hongqiang Wang, Shuibo Xie, Xiaowen Zhang, Junwen Lv, Lei Ding, Wenfa Tan, Kathryn A. Mumford, Xiaoyan Wu |
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| Rok vydání: | 2018 |
| Předmět: |
inorganic chemicals
China Health Toxicology and Mutagenesis chemistry.chemical_element 02 engineering and technology 010501 environmental sciences Toxicology 01 natural sciences chemistry.chemical_compound Adsorption Biochar Soil Pollutants Radioactive Dissolution 0105 earth and related environmental sciences Ions Aqueous solution Polyphosphate Temperature technology industry and agriculture Biosorption General Medicine Uranium Biodegradation 021001 nanoscience & nanotechnology Pollution Biodegradation Environmental chemistry Charcoal 0210 nano-technology Oxidation-Reduction Nuclear chemistry |
| Zdroj: | Environmental Pollution. 242:778-787 |
| ISSN: | 0269-7491 |
| DOI: | 10.1016/j.envpol.2018.07.050 |
| Popis: | It has generally been assumed that the immobilization of U(VI) via polyphosphate accumulating microorganisms may present a sink for uranium, but the potential mechanisms of the process and the stability of precipitated uranium under aerobic conditions remain elusive. This study seeks to explore the mechanism, capacity, and stability of uranium precipitation under aerobic conditions by a purified indigenous bacteria isolated from acidic tailings (pH 6.5) in China. The results show that over the treatment ranges investigated, maximum removal of U(VI) from aqueous solution was 99.82% when the initial concentration of U(VI) was 42 μM, pH was 3.5, and the temperature was with 30 °C much higher than that of other reported microorganisms. The adsorption mechanism was elucidated via the use of SEM-EDS, XPS and FTIR. SEM-EDS showed two peaks of uranium on the surface. A plausible explanation for this, supported by FTIR, is that uranium precipitated on the biosorbent surfaces. XPS measurements indicated that the uranium product is most likely a mixture of 13% U(VI) and 87% U(IV). Notably, the reoxidation experiment found that the uranium precipitates were stable in the presence of Ca2+ and Mg2+, however, U(IV) is oxidized to U(VI) in the presence of NO3- and Na+ ions, resulting in rapid dissolution. It implies that the synthesized Leifsonia sp. coated biochar could be utilized as a green and effective biosorbent. However, it may not a good choice for in-situ remediation due to the subsequent re-oxidation under aerobic conditions. These observations can be of some guiding significance to the application of the bioremediation technology in surface environments. |
| Databáze: | OpenAIRE |
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