首页|绿脱石结构Fe(Ⅲ)还原程度对氧化过程·OH形成及有机质矿化的影响

绿脱石结构Fe(Ⅲ)还原程度对氧化过程·OH形成及有机质矿化的影响

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土壤和沉积物有氧-无氧界面黏土矿物结构Fe(Ⅱ)氧化产生的羟自由基(·OH)在有机物质转化过程中具有重要作用。土壤和沉积物黏土矿物结构Fe(Ⅲ)的还原程度会随环境条件变化而不同，然而，关于含铁黏土矿物还原程度[Fe(Ⅱ)/Fe总]对氧化过程中·OH的形成及有机质矿化的影响尚不明确。本研究以富铁绿脱石为黏土矿代表，研究了不同还原程度绿脱石[Fe(Ⅱ)/Fe总:15%、22%、39%和56%]有氧氧化产生·OH的机制及该过程对溶解性有机质(DOM)转化的差异。结果表明，当不同还原程度绿脱石的悬浊液体系中结构Fe(Ⅱ)浓度为2。2 mmol·L-1时，随着还原程度从15%增加到56%，其氧化120 min后·OH的累积浓度从13。6 μmol·L-1增加到27。1 μmol·L-1，单位O2转化为·OH的效率从3。3%提高到5。9%。傅里叶变换红外光谱(FTIR)、氮蓝四唑(NBT)猝灭实验和2，2'-联吡啶(BPY)钝化边缘反应位点的结果证明了还原程度为15%的绿脱石主要存在二八面体Fe(Ⅱ)[Al-Fe(Ⅱ)]，并在边缘位点活化O2产生·OH;而还原程度为56%的绿脱石除二八面体Fe(Ⅱ)外，还存在高活性三八面体[Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)]，底面位点和边缘位点均可活化O2产生·OH，并且O2在底面位点还原形成·OH效率更高。氧化过程中·OH矿化溶解性有机质(DOM)形成CO2的含量随绿脱石的还原程度的升高而升高。因此，与低还原程度绿脱石(15%)相比，高还原程度的绿脱石(56%)存在高活性三八面体并能从底面位点形成·OH从而提高了·OH生成的效率并进一步促进了DOM的矿化。
Effects of reduction degree of structure Fe(Ⅲ)in chlorite on hydroxyl radical formation and mineralization of organic matter during oxidation
Hydroxyl radicals(·OH)produced by the oxidation of structure Fe(Ⅱ)in clay mineral at the aerobic-anaerobic interface of soil and sediment play an important role in the transformation of organic matter.The reduction degree of structure Fe(Ⅲ)in the clay mineral of soil and sediment varies with environmental conditions.However,the effect of the reduction degree of iron-containing clay minerals[Fe(Ⅱ)/Fe total]on the formation of·OH and the mineralization of organic matter during the oxidation process is still unclear.Taking iron-rich nontronite(NAu-2)as the representative clay ore,the oxidation mechanism of NAu-2 with different reduction degrees(Fe(Ⅱ)/Fe total:15%,22%,39%,and 56%)to produce·OH and the difference of this process to natural DOM transformation were studied.The results demonstrated that when the concentration of structural Fe(Ⅱ)in NAu-2 suspension was 2.2 mmol·L-1,the reduction degree increased from 15%to 56%,cumulative concentration of·OH increased from 13.6 to 27.1 μmol·L-1 after 120 min of oxidation,and the conversion efficiency of unit O2 to·OH increased from 3.3%to 5.9%.The results of Fourier transform infrared spectroscopy(FTIR),Nitrotetrazolium blue chloride(NBT)deactivation experiments,and 2,2'-dipyridyl(BPY)edge reaction site passivation proved that the chlorite with 15%reduction degree mainly existed in dioctahedral Fe(Ⅱ)[Al-Fe(Ⅱ)],and it activated O2 at the edge site to produce·OH.In addition to octahedral Fe(Ⅱ),highly active trioctahedral Fe(Ⅱ)[Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)]were present in chlorite with a reduction degree of 56%.Both the basal and marginal sites could activate O2 to produce·OH,and the reduction efficiency of O2 to form·OH at the basal site was higher.The CO2content formed by·OH mineralized dissolved organic matter(DOM)increased with the increase of NAu-2 reduction degree.Therefore,compared with the low reduction degree of NAu-2(15%),the high reduction degree of NAu-2(56%)has a highly active trioctahedral and can form·OH from the bottom site,which improves the efficiency of·OH formation and further promotes the mineralization of DOM.

nontronitestructural Fe(Ⅱ)reduction extenthydroxyl radicals(·OH)natural DOM transformation

肖艳琦、符俊宏、刘细祥、廖文娟、张娜、崔浩杰

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湖南农业大学资源学院,长沙 410128

广西民族大学材料与环境学院,广西高校环境友好材料及碳中和新技术重点实验室,广西先进结构材料与碳中和重点实验室,南宁 530006

中国地质大学(武汉)生物地质与环境地质国家重点实验室,武汉 430074

衡水学院,河北省湿地生态与保护重点实验室,河北 衡水 053000

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绿脱石 结构二价铁 还原程度 羟自由基(·OH) 天然DOM转化

国家自然科学基金国家自然科学基金国家自然科学基金湖南省教育厅优秀青年项目中国地质大学生物地质与环境地质国家重点实验室项目河北省湿地生态与保护重点实验室项目河北省自然科学基金广西先进结构材料与碳中和重点实验室开放基金

422772914170204041967030275116GBL22109hklk202302D2022111001GXAMCN23-3

2024

10.11654/jaes.2023-0983

农业环境科学学报
农业部环境保护科研监测所 中国农业生态环境保护协会

农业环境科学学报

CSTPCD北大核心
影响因子：1.52
ISSN：1672-2043
年,卷(期)：2024.43(5)
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