Cr(Ⅲ)在不同氧化还原环境中的转化  

Transformation of Cr(Ⅲ)in different redox environments

作　　者：李刚 王聪 解科峰 魏小雅 牛宏 LI Gang;WANG Cong;XIE Kefeng;WEI Xiaoya;NIU Hong(Central-Southern Safety&Environment Technology Institute Co.,LTD.,Wuhan 430051,China;Hubei Water Resources and Hydropower Planning,Survey and Design Institute Co.,Wuhan 430070,China;Hubei Airports Group Company Co.,Ltd.,Wuhan 430302,China;College of Resources and Environmental,South-Central Minzu University,Wuhan 430074,China)

机构地区：[1]中南安全环境技术研究院股份有限公司,武汉430051 [2]湖北省水利水电规划勘测设计院有限公司,武汉430070 [3]湖北机场集团有限公司,武汉430302 [4]中南民族大学资源与环境学院,武汉430074

出　　处：《地质科技通报》2025年第2期389-400,共12页Bulletin of Geological Science and Technology

基　　金：中央高校基本科研业务费专项资金项目(CZY23011)。

摘　　要：当环境处在氧化还原波动时,含Fe(Ⅱ)黏土矿物如何影响Cr(Ⅲ)的吸附解吸和价态转化,值得深入研究。通过制备氧化态、还原态、还原再氧化态3种不同状态的蒙脱石,对Cr(Ⅲ)进行了吸附实验,测定吸附值、Fe(Ⅱ)/总Fe、羟基自由基浓度以及价态变化,并且对吸附前后的蒙脱石固体材料进行了X射线光电子能谱(XPS)、X射线衍射(XRD)、傅里叶变换红外吸收光谱仪(FTIR)表征。结果显示,氧化态和还原态蒙脱石对Cr(Ⅲ)的吸附率随p H值的增大而增加,还原态蒙脱石吸附率最高,因为铁含量最高,这2种状态下不发生价态变化。而还原再氧化态蒙脱石的吸附率最小,是由于Fe(Ⅱ)迅速将氧气活化产生羟基自由基,Cr(Ⅲ)被迅速氧化为Cr(Ⅵ),pH值越低,氧化率越高,在8 h测得Cr(Ⅵ)又被还原性物质Fe(Ⅱ)再次还原为Cr(Ⅲ)。通过Fe(Ⅱ)/总Fe值及羟基自由基浓度变化,验证了氧化还原环境发生改变,Fe(Ⅱ)的消耗率和羟基自由基的生成率有较高的相关性。通过实验可以发现,还原再氧化后会产生羟基自由基,影响Cr(Ⅲ)的吸附解吸,并且强氧化性的羟基自由基可以氧化Cr(Ⅲ)为有毒的Cr(Ⅵ),验证了地下环境氧化还原波动后会使铬出现“返黄”的假定。[Objective]It is still unclear about the effects of redox fluctuations by Fe(Ⅱ)-containing clay minerals on the adsorption-desorption and valence transformation of Cr(Ⅲ).[Methods]In this work,Cr(Ⅲ)adsorption experiments were carried out by preparing montmorillonite in three different conditions(oxidized,reduced,and reduced-reoxidized)to determine the adsorption value,Fe(Ⅱ)/total Fe ratio,hydroxyl radical concentration,as well as valence changes.The montmorillonite solid materials before and after adsorption were characterized via X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),and Fourier transform infrared(FTIR).[Results]The results revealed that the adsorption rate of Cr(Ⅲ)by oxidized and reduced montmorillonite increased with elevated pH,and that reduced montmorillonite had the highest adsorption rate due to its highest Fe content,with no valence change occurring in these two states.The adsorption rate of reduced-reoxidized montmorillonite was the lowest,which was due to the rapid activation of oxygen by Fe(Ⅱ),producing hydroxyl radicals.Cr(Ⅲ)was rapidly oxidized to Cr(Ⅵ),and the lower the pH,the higher the oxidation rate.Cr(Ⅵ)was reduced back to Cr(Ⅲ)by the reducing substance Fe(Ⅱ)after 8 hours.The high correlation between the consumption rate of Fe(Ⅱ)and the generation rate of hydroxyl radicals was verified by changes in the Fe(Ⅱ)/total Fe ratio and hydroxyl radical concentration,which altered the redox environment.[Conclusion]Experiments have shown that hydroxyl radicals are generated after reduction and reoxidation,which affects the adsorption and desorption of Cr(Ⅲ),and strongly oxidizing hydroxyl radicals can oxidize Cr(Ⅲ)to toxic Cr(Ⅵ),supporting the hypothesis that chromium reverts to yellowish color after redox fluctuations in the underground environment.

关 键 词：三价铬(Cr(Ⅲ)) 氧化还原 吸附解吸 羟基自由基 

分 类 号：X50[环境科学与工程—环境工程]