镉在不同氧化还原环境中的吸附解吸行为  

Adsorption and desorption behavior of cadmium in different redox environments

作　　者：李刚 王聪 解科峰 伍杭 牛宏 LI Gang;WANG Cong;XIE Kefeng;WU Hang;NIU Hong(Central-Southern Safety&Environment Technology Institute Co.,Ltd.,Wuhan 430000,China;Hubei Water Resources and Hydropower Planning,Survey and Design Institute Co.,Wuhan 430070,China;Hubei Traffic Engineering Testing Center Co.,Wuhan 430074,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430000 [2]湖北省水利水电规划勘测设计院有限公司,武汉430070 [3]湖北交通工程检测中心有限公司,武汉430074 [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1期241-250,共10页Bulletin of Geological Science and Technology

摘　　要：地下氧化还原环境变化影响重金属在土壤中的吸附解吸,其影响机制尚不明朗。制备了不同氧化还原环境的蒙脱石,采用静态吸附实验及表征手段探究了不同氧化还原环境对镉吸附的影响。结果显示,还原态蒙脱石M-RD和氧化态蒙脱石M-OX氧化还原性变化不大,还原再氧化态蒙脱石M-RO中发生的氧化还原反应最强烈,还原性逐渐下降。M-RD吸附效果比M-OX更好,尽管M-RD再次氧化后,部分被吸附的Cd会被释放出来,但效果还是高于M-OX。M-RD再次接触氧气时,与氧气发生氧化反应,产出大量羟基自由基,而M-OX和M-RD几乎不产生羟基自由基。M-RD再次氧化后,Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)-OH重排-OH弯曲振动特征吸收峰和Si-O四面体结构的特征吸收峰产生变动,表明蒙脱石发生了结构摄动,判断是其中的Fe(Ⅱ)失去电子被氧化成Fe(Ⅲ),导致了蒙脱石结构的变化,使得蒙脱石比表面积、孔容和平均孔径均增大了,氧化还原条件变化影响其吸附性能,削弱了蒙脱石对Cd的吸附,导致吸附的Cd被再次释放。本研究揭示了地下环境氧化还原条件影响Cd吸附解吸的机理,可为氧化还原环境不断变化的土壤污染修复治理提供理论指导。[Objective]Changes in subsurface redox environment can affect the adsorption and desorption of heavy metals in soils;however,the underlying mechanisms of these effects remain unclear.[Methods]In this work,montmorillonite with different redox environments was prepared,and the effects of different redox environments on cadmium adsorption were assessed via static adsorption experiments and various characterization techniques.[Results]The results revealed minimal changes in the redox properties of both reduced montmorillonite M-RD and oxidized montmorillonite M-OX.The strongest redox reaction was observed in reduced reoxidized montmorillonite M-RO,which showed a gradual decrease in the reducing properties.M-RD exhibited superior cadmium adsorption compared to M-OX;however,upon reoxidation,some adsorbed cadmium was released from M-RD,although the adsorption was still more effective than in M-OX.Re-exposure of M-RD to oxygen initiated an oxidation reaction,generating numerous hydroxyl radicals,a phenomenon not observed in M-OX or M-RD alone.[Conclusion]Upon reoxidation of M-RD,changes occurred in the characteristic absorption peaks associated with Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)-Fe(Ⅱ)-OH rearrangement-OH bending vibrations and the Si-O tetrahedral structure,indicating structural uptake of montmorillonite.This suggests that Fe(Ⅱ)in the structure lost electrons,transforming into Fe(Ⅲ),thereby causing a structural change in montmorillonite.These changes led to increased specific surface area,pore volume,and average pore size of montmorillonite,ultimately affecting its adsorption capacity.The altered redox conditions weakened the adsorption of Cd,causing its release from montmorillonite.Uncovering the mechanisms of cadmium adsorption and desorption affected by redox conditions in subsurface environments can provide theoretical insights for the remediation and treatment of soil pollution in dynamic redox settings.

关 键 词：镉 氧化还原 吸附解吸 羟基自由基 

分 类 号：X142[环境科学与工程—环境科学]