铁盐淋洗剂对稀土污染土壤的淋洗修复研究  

Remediation of rare earth element-contaminated paddy soil by ferric salts washing

作　　者：李鸿博 张奕 丁梓奕[1,2,3] 龙诗琴 陈情泽 朱润良[1,2,3] LI Hongbo;ZHANG Yi;DING Ziyi;LONG Shiqin;CHEN Qingze;ZHU Runliang(CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室/广东省矿物物理与材料研究开发重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049

出　　处：《地球化学》2024年第1期110-121,共12页Geochimica

基　　金：广东省基础与应用基础研究重大项目(2019B030302013);国家重点研发计划(2021YFC2901701);中国科学院青年创新促进会专项项目(2020347)联合资助。

摘　　要：稀土矿的大量开采,加剧了土壤污染,危害居民健康。本研究采用不同三价铁盐(Fe^(2)(SO_(4))_(3)、Fe(NO_(3))_(3)和FeCl_(3))对稀土污染的农田土壤进行淋洗修复,同时对比其他无机盐(亚铁盐、镁盐、铵盐和钠盐)的淋洗效果;并研究三价铁盐淋洗剂浓度、液固比和淋洗时间对稀土元素(REE)去除效果的影响。结果表明,三价铁盐对REE的淋洗率高达41.7%~54.3%,显著高于其他无机盐(0.2%~26.8%);三价铁盐的最佳淋洗时间为1440 min,当淋洗剂浓度从5 mmol/L增加到50 mmol/L的过程中,土壤中REE淋洗率显著增加,淋洗率随淋洗液固比(1∶1~5∶1)的升高而增加,其中,淋洗剂浓度对REE去除率的促进作用显著大于液固比。在优化淋洗条件下,Fe_(2)(SO_(4))_(3)对REE的淋洗率为54.3%,显著高于Fe(NO_(3))_(3)(46.1%)和FeCl_(3)(41.7%),这主要是由于REE^(3+)与SO_(4)^(2−)易发生络合,促进了REE的溶出。三价铁盐对土壤中REE的高效去除,主要是由于酸解作用、较强的阳离子交换能力,以及阴离子配体与稀土元素的络合作用。此外,三价铁盐对MREE的去除效率显著高于LREE土和HREE,表现出明显的分异特征。上述研究可为稀土污染土壤的修复治理提供指导与借鉴。The massive mining of rare earth mines has aggravated soil pollution and endangered the health of the residents.In this study,different trivalent iron salts(ferric sulfate,ferric nitrate,and ferric chloride)were used in the remediation of rare earth element(REE)contaminated paddy soil through soil washing.Besides,the washing effects of other inorganic salts(ferrous,magnesium,ammonium,and sodium salts)were compared.The results showed that the REE removal rates of trivalent iron salts were 41.7%–54.3%,which were significantly higher than those of the other inorganic salts(0.2%–26.8%).The optimum washing time of trivalent iron salts was 1440 min.The removal rates of REE in soil increased significantly when the content of the trivalent iron salts increased from 5 mmol/L to 50 mmol/L.The washing rate increased with the increase of the washing liquid-solid ratio(1∶1–5∶1).It is worth noting that the agent content is a more crucial factor controlling the REE removal.Under the optimized washing conditions,the REE removal rate of iron sulfate was 54.3%,which was significantly higher than those of iron nitrate(46.1%)and iron chloride(41.7%).This is mainly due to the stronger complexation of sulfate with REE ions,which promoted the REE removal.The excellent performance of the trivalent iron salts in REE removal is mainly due to their acidolysis,strong cation exchange capacity,and strong complexation of anionic ligands with REE ions.In addition,iron sulfate washing resulted in significant REE differentiation.The trivalent iron salt washing preferentially removes medium-REE in the soil.This study can provide guidance and reference for the remediation of REE-contaminated soils.

关 键 词：铁盐 硫酸铁 土壤淋洗 稀土元素 分异特征 

分 类 号：X53[环境科学与工程—环境工程]