钒(V^(3+))与水钠锰矿共沉淀的相互作用及对Pb^(2+)和Zn^(2+)的去除研究

A Study on the Interaction between Vanadium(V^(3+))and Birnessite Coprecipitation and Its Removal of Pb^(^(^(2+)))and Zn^(^(^(2+)))

【目的】随着科技的发展,钒(V)元素在材料上的应用逐渐成为关注的焦点,但随之而来的潜在环境危险也逐渐突出。因此,对于V在环境中迁移转化的行为值得深入研究。研究表明,土壤及沉积物质中的矿物对环境中污染元素的迁移转化有较强的控制作用,且环境中钒与氧化锰的含量正相关关系。此外,水钠锰矿是环境中较为常见的层状氧化锰,因其分布广和活性强,常作为层状氧化锰的模式矿物进行研究。因此,水钠锰矿与V元素的相互作用及环境效应有待进一步探究。【方法】通过V^(3+)阳离子与水钠锰矿共沉淀方式制备含V的水钠锰矿,采用XRD、FTIR、SEM和XAS等技术以及湿法化学和等温吸附实验相结合,分析V与水钠锰矿共沉淀后,V对水钠锰矿形貌特征及性质的影响,以及V在水钠锰矿中的存在形态。【结果】随着V^(3+)含量的增加,水钠锰矿c轴方向尺寸从10.98 nm显著下降到2.96 nm,比表面积有增大趋势,而水钠锰矿花球状颗粒显著减小。水钠锰中的V元素最终是五价,少部分的V5+进入了水钠锰矿层内减少了Mn4+的含量,降低了空位含量;其它较多的则可能以VO43−或和V6O162−的阴离子团或簇的方式存在于层间和吸附在边面位点。且在重金属去除中,随着掺V含量增加,水钠锰矿对Pb^(2+)去除率增加,但对Zn^(2+)去除率降低。【结论】V^(3+)与水钠锰矿的共沉淀,使得水钠锰矿负电荷增多,导致K+离子含量上升;同时V元素被氧化为V5+,可以不同形式存在于水钠锰矿的层间、层内和边面,从而增强了水钠锰矿对Pb^(2+)和Zn^(2+)的选择性去除。上述结论为V的环境行为和归趋提供了理论基础。

[Objective]With the development of science and technology,the application of vanadium(V)in materials has gradually becoming become the focus of attention,but the potential environmental hazards are also gradually becoming prominent.Therefore,the migration and transformation behavior of V in the environ⁃ment is worthy of further study.The minerals in soil and sediment have a strong control on the migration and transformation of pollution elements in the environment.And there is a positive correlation between the contents of vanadium and manganese oxide in the environment.In addition,birnessite,as a common layered manganese oxide in the environment,is often studied as a model mineral of layered manganese oxides because of its wide distribution and strong activity.Therefore,the interaction between birnessite and V and its environmental ef⁃fects need to be further explored.[Method]V-doped birnessite was prepared by coprecipitation of V^(3+)cation and birnessite in this study,and XRD,FTIR,SEM,XAS,wet chemistry and isothermal adsorption experiments were used to analyze the influence of V on the morphology and properties of birnessite and the existing forms of V in birnessite.[Result]With the increase of V^(3+)content,the c-axis dimension size of birnessite decreased sig⁃nificantly from 10.98 nm to 2.96 nm,the specific surface area increased,and the flower spherical particles of birnessite decreased significantly.The V element in birnessite was pentavalent,a small part of V5+entered the layer of birnessite,which reduced the content of Mn4+and the vacancy content.The other V5+existed in the in⁃terlayer and on the edge sites in the form of VO43−or V6O162−.In the process of heavy metal removal,with the in⁃crease of V content,the removal rate of Pb^(2+)increased and that of Zn^(2+)decreased.[Conclusion]The doping V^(3+)increases the negative charge of birnessite and increases K+content.V element is oxidized to V5+,which can ex⁃ist in different forms in the interlayer,layer and on the edge of birnessite,thus enhancing the selective removal of Pb^(2+)and Zn^(2+)by birnessite.These conclusions provide a theoretical basis for the environmental behavior and fate of V.