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高校地质学报 ›› 2023, Vol. 29 ›› Issue (5): 705-712.DOI: 10.16108/j.issn1006-7493.2022031

• 岩石·矿床·地球化学 • 上一篇    下一篇

共存铁和锰氧化物氧化和固定Ce(III) 的机制

赵涵玥,周跃飞*,李晓松,谢巧勤,陈天虎   

  1. 合肥工业大学 资源与环境工程学院,合肥 230009
  • 出版日期:2023-10-11 发布日期:2023-10-10

Mechanisms of Ce(III) Oxidation and Fixation by Coexisting Iron and Manganese Oxides

ZHAO Hanyue,ZHOU Yuefei*,LI Xiaosong,XIE Qiaoqin,CHEN Tianhu   

  1. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
  • Online:2023-10-11 Published:2023-10-10

摘要: 该研究通过批次和动态实验,考查含锰褐铁矿和合成针铁矿对Ce(III)的氧化和固定作用,并在此基础上探讨共存铁和锰氧化物氧化和固定Ce的机制及地质意义。批次实验结果显示,含锰褐铁矿对Ce的氧化和固定有重要促进作用,在初始Ce浓度为6000 μg/L,含锰褐铁矿添加量为1 g/L时,可在48 h实现对Ce的完全固定;初始Ce(III)浓度在300~4500 μg/L时,含锰褐铁矿对Ce(III)氧化和沉淀的促进作用与Mn含量正相关,而合成针铁矿相对于无矿体系体现出抑制效应。动态实验结果显示,对高锰褐铁矿固定的Ce,其分布不受锰氧化物的制约,与铁氧化物的分布一致。对结果的分析表明Ce氧化和沉淀的过程为:吸附—氧化—CeO2沉淀生成—CeO2自催化氧化Ce(III);锰和铁氧化物共存时,对Ce氧化和固定的贡献分别是:前者促进Ce氧化,后者通过静电吸附作用促进CeO2的固定。研究对于解释“锰氧化物氧化Ce(III)的能力强于铁氧化物,但二者共存时铁氧化物更易于固定Ce”这一地质现象有一定启示意义。

关键词: 褐铁矿, 锰氧化物, 针铁矿, Ce(III), CeO2, 自催化氧化

Abstract: In this study, we conducted bulk and dynamic experiments to investigate the efficiency of Ce (III) oxidation and fixation by Mn-contained limonite and goethite. Based on experimental results, the mechanism of Ce oxidation and fixation by coexisting iron and manganese, and its geological significance, are discussed. Results of bulk experiments show that Mn-contained limonite has a high performance on the oxidation and fixation of Ce; Ce was totally removed after 48 hours under solution with Ce concentration of 6000 μg/L and limonite concentration of 1 g/L. For experiments with initial Ce concentrations of 300 to 4500 μg/L, Ce removal is positively correlated with Mn content for limonite experiments. As for goethite, it decreased Ce removal when comparing to the control experiments. Results of dynamic adsorption experiments show that for high-Mn limonite, the distribution of Ce is constrained not by Mn minerals, but by iron oxides. The results of this study indicates that: (1) the process of Ce oxidation and precipitation is adsorption of Ce (III) -oxidation of Ce(III) to Ce(IV)-precipitation of Ce(IV) minerals-autocatalytic oxidation of Ce(III) to Ce(IV) by CeO2, and (2) the contributions of coexisted Mn and Fe oxides to Ce oxidation and fixation are Mn oxides promoting the oxidation of Ce(III) and Fe oxides promoting the precipitation of CeO2 through electrostatic attraction. This study is significant in explaining the geological phenomenon that although Mn oxides have higher Ce(III) oxidation ability than that of Fe oxides, under Fe- and Mn-oxides coexisting conditions, Ce tends to be fixed by Fe oxides.

Key words: limonite, manganese oxide, goethite, Ce(III), CeO2, autocatalytic oxidation

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