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6000μg/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300~4500μg/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—CeO_(2)沉淀生成—CeO_(2)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CeO_(2)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。
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 6000μg/L and limonite concentration of 1 g/L.For experiments with initial Ce concentrations of 300 to 4500μg/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 CeO_(2),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 CeO_(2) 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.
作者
赵涵玥
周跃飞
李晓松
谢巧勤
陈天虎
ZHAO Hanyue;ZHOU Yuefei;LI Xiaosong;XIE Qiaoqin;CHEN Tianhu(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《高校地质学报》
CAS
CSCD
北大核心
2023年第5期705-712,共8页
Geological Journal of China Universities
基金
国家自然科学基金(41872043)资助。
