Fe(Ⅱ)_(aq)与纤铁矿-胡敏酸复合物交互反应及其结构转化过程研究  

The Study of the Interaction of Aqueous Fe(Ⅱ) and Lepidocrocite-humic Acid Compounds and the Phase Transformation

作　　者：王玉洁[1] 雷琴凯 卜红玲 童辉 董乐恒 陈曼佳 刘承帅 WANG Yujie;LEI Qinkai;BU Hongling;TONG Hui;DONG Leheng;CHEN Manjia;LIU Chengshuai(School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006,P.R.China;National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China/Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management/Institute of Eco-environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,P.R.China;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,P.R.China)

机构地区：[1]广东工业大学环境科学与工程学院,广东广州510006 [2]广东省科学院生态环境与土壤研究所/华南土壤污染控制与修复国家地方联合工程研究中心/广东省农业环境综合治理重点实验室,广东广州510650 [3]中国科学院地球化学研究所环境地球化学国家重点实验室,贵州贵阳550081

出　　处：《生态环境学报》2022年第4期777-784,共8页Ecology and Environmental Sciences

基　　金：广东省自然科学基金项目(2021A1515011883,2019A1515011603);广东省科学院实施创新驱动发展能力建设专项(2020GDASYL-20200105002,2020GDASYL-20200102019)。

摘　　要：Fe(Ⅱ)与铁氧化物的相互作用过程是铁循环的重要组成部分,影响着土壤中各种元素的地球化学过程。目前关于Fe(Ⅱ)与铁氧化物相互作用的地球化学机制已基本厘清。然而,土壤环境中,铁氧化物和有机质常常结合并形成铁氧化物-有机质(Fe-OM)复合物,使其形成结构更为复杂、活性变化更大的结构单元。Fe(Ⅱ)作用下,Fe-OM复合物结构转化的过程及其作用机制更是缺乏系统性研究。因此,该文以纤铁矿与胡敏酸复合物(Lep-HA)为研究对象,通过室内模拟实验,借助铁稳定同位素标记及XRD、SEM、XPS等矿物结构表征手段,研究在中性厌氧条件下,Fe(Ⅱ)与Lep-HA复合物相互作用电子传递和复合物结构转化的过程及其机制。结果表明:Fe(Ⅱ)与Lep-HA复合物可发生铁原子交换,铁原子交换率可达64.31%-91.82%;铁原子交换速率受Lep-HA复合物中C/Fe比例的影响,C/Fe比例越高铁原子交换速率越低。Lep-HA复合物中胡敏酸可通过降低Fe(Ⅱ)在纤铁矿表面的吸附量等作用,抑制Fe(Ⅱ)与Lep-HA之间的铁原子交换速率。XRD和SEM分析表明,胡敏酸的存在抑制了纤铁矿晶相转变及二次成矿过程;反应30 d时,纯相纤铁矿均转化为针铁矿,不同比例Lep-HA复合物则发生重结晶,生成结晶度更强及晶胞粒径更大的纤铁矿。XPS分析结果表明,反应后Fe(Ⅱ)可与胡敏酸形成Fe-C配体,且Lep-HA复合物结构中C-C基团含量由86.17%降至69.86%,而O-C=O基团含量由13.86%增至16.13%。以上研究结果较系统地阐明了Fe(Ⅱ)和Fe-OM复合物相互作用的地球化学机制,可为深入理解土壤中Fe和C等元素耦合循环的环境地球化学行为提供一定的理论依据。The interaction between aqueous Fe(Ⅱ)(Fe(Ⅱ)_(aq))and iron oxide is an important part of the iron cycle,which plays an important role in the geochemical processes of various elements.The geochemical mechanism of Fe(Ⅱ)and iron oxides interaction has been well studied.However,the mechanism of the interaction between Fe(Ⅱ)_(aq)and iron oxide-humic matter compounds is rarely studied.In the soil environment,iron oxide and organic matter often coexist and cooperate as iron oxide-organic matter compounds with a complex composition and highly reactive activities.In this study,lepidocrocite-humic acid compounds(Lep-HA)were prepared,and the interaction between Fe(Ⅱ)_(aq)and Lep-HA was investigated in the lab under the anaerobic condition by means of iron stable isotope labeling,such as the XRD,SEM and XPS analysis methods.The results showed that electron transfers can occur between Fe(Ⅱ)_(aq)and Lep-HA with rates of 64.31%‒91.82%.The electron transfer rate was affected by the C/Fe ratio in Lep-HA,and the higher the C/Fe ratio the lower the iron atom exchange rate.Analyses showed that the presence of humic acids in Lep-HA compounds could decrease the adsorption of Fe(Ⅱ)on the surface of lepidocrocite,and further inhibited the electron transfer rate.XRD and SEM results showed that the presence of humic acids in Lep-HA compounds also inhibited the phase transformation of lepidocrocite.After 30 days of reaction,lepidocrocite could be transformed into goethite by the Fe(Ⅱ)_(aq).However,the Lep-HA compounds with different C/Fe ratios were recrystallized into lepidocrocite with stronger crystallinity and larger cell sizes.Fe-C bond was found by the XPS analysis.The content of C-C groups in Lep-HA compounds decreased from 86.17%to 69.86%,while the O-C=O group increased from 13.86%to 16.13%after 30 days of reaction.This study would provide a theoretical support for interpreting the geochemical mechanism of the interaction between Fe(Ⅱ)and iron oxide-OM compounds,and provide a theoretical basis for understanding t

关 键 词：Fe(Ⅱ) 有机质 纤铁矿-胡敏酸复合物 结构转化 铁原子交换 铁循环 

分 类 号：S153[农业科学—土壤学] X142[农业科学—农业基础科学]