A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp strain KR21-2
A specific Ce oxidation process during sorption of rare earth elements on biogenic Mn oxide produced by Acremonium sp strain KR21-2
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DOI：
10.1016/j.gca.2010.07.010
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发表时间：
2010-10-01
影响因子：
5
通讯作者：
Ohnuki, Toshihiko
中科院分区：
文献类型：
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作者：
Tanaka, Kazuya;Tani, Yukinori;Ohnuki, Toshihiko
稀土元素在天然和人工合成锰氧化物上的吸附和铈的氧化已被许多研究者所研究。虽然锰（II）氧化微生物被认为在大多数自然环境中的锰氧化物的形成中发挥重要作用，铈氧化生物锰氧化物和微生物的铈氧化过程的相关性还没有得到很好的理解。因此，在这项研究中，我们进行了吸附实验的生物锰氧化物的枝顶孢属物种菌株KR 21 -2。在pH3.8时，生物氧化锰（加菌丝）与10 mmol/LNaCl溶液的分配系数K（d）（REE）呈现较大的正Ce异常和凸形四分体效应变化，这与前人用人工合成氧化锰的结果一致。正Ce异常是由Ce（III）被生物Mn氧化物氧化成Ce（IV）引起的，这通过Ce L（III）-边XANES谱的分析得到证实。随着pH值的增加，正Ce异常和凸四分体效应变得不那么明显。此外，在大于6.5的pH下观察到负Ce异常，表明Ce（IV）在溶液中稳定（
Sorption of rare earth elements (REEs) and Ce oxidation on natural and synthetic Mn oxides have been investigated by many researchers. Although Mn(II)-oxidizing microorganisms are thought to play an important role in the formation of Mn oxides in most natural environments, Ce oxidation by biogenic Mn oxide and the relevance of microorganisms to the Ce oxidation process have not been well understood. Therefore, in this study, we conducted sorption experiments of REEs on biogenic Mn oxide produced by Acremonium sp. strain KR21-2. The distribution coefficients, K(d)(REE), between biogenic Mn oxide (plus hyphae) and 10 mmol/L NaCl solution showed a large positive Ce anomaly and convex tetrad effect variations at pH 3.8, which was consistent with previous works using synthetic Mn oxide. The positive Ce anomaly was caused by oxidation of Ce(III) to Ce(IV) by the biogenic Mn oxide, which was confirmed by analysis of the Ce L(III)-edge XANES spectra. With increasing pH, the positive Ce anomaly and convex tetrad effects became less pronounced. Furthermore, negative Ce anomalies were observed at a pH of more than 6.5, suggesting that Ce(IV) was stabilized in the solution (