磷酸盐对镉在纤铁矿上吸附行为的影响机制研究  

Effect of phosphate on Cd(II)adsorption on the surface of lepidocrocite

作　　者：梁恒尧 郭楚玲 李晓飞[3] 任美慧 陈锴 殷美玲 党志 LIANG Hengyao;GUO Chuling;LI Xiaofei;REN Meihui;CHEN Kai;YIN Meiling;DANG Zhi(School of Environment and Energy,South China University of Technology,Guangzhou 510006;The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters,Ministry of Education,South China University of Technology,Guangzhou 510006;School of Environmental and Chemical Engineering,Foshan University,Foshan 528000)

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]华南理工大学,工业聚集区污染控制与生态修复教育部重点实验室,广州510006 [3]佛山大学环境与化工学院,佛山528000

出　　处：《环境科学学报》2025年第1期166-176,共11页Acta Scientiae Circumstantiae

基　　金：广东省自然科学基金面上项目(No.2024A1515010861)。

摘　　要：铁氧化物对有毒金属的吸附广泛存在于自然环境中.众所周知,氧阴离子可以通过协同或者竞争效应改变微量金属元素的吸附行为.然而,具体的共同吸附机制尚不完全清楚.本研究通过宏观吸附实验、原位衰减全反射傅立叶变换红外光谱(ATR-FTIR)和X射线光电子能谱(XPS)等方法,研究了磷酸盐存在下,镉(Cd(II))在合成纤铁矿(Lep)上的吸附行为.等温吸附实验结果表明,在不存在磷酸盐且Cd(II)初始浓度为1 mmol·L^(-1)的体系中,Lep对Cd(II)的吸附量为1.91 mg·g^(-1).当体系中磷酸盐与Cd(II)的物质的量比分别为1∶1和2∶1时,Lep对Cd(II)的吸附量较不存在磷酸盐时分别提高了3.67倍和16.62倍;当磷酸盐与Cd(II)的物质的量比为5∶1时,Lep对Cd(II)的吸附量较不存在磷酸盐时却只提高了12.93倍.吸附边结果表明,pH对磷酸盐介导的Lep对Cd(II)的吸附行为影响较小,这可能是因为磷酸盐具有很强的配位作用.XPS和ATR-FTIR分析表明,Cd(II)可以和Lep表面的磷酸盐络合形成三元络合物(Cd(II)-磷酸盐-Lep),并且磷酸盐主要通过内圈络合与Lep表面结合.此外,2D-COS分析表明,在Lep表面形成了多种构型的磷酸盐-Cd(II)-Lep三元络合物,其中包括双齿双核和单齿双核络合物.这些络合物构型是磷酸盐与Cd(II)在Lep表面通过形成三元络合物协同吸附的典型模式.The adsorption of toxic metals by iron oxides is widespread in natural environments.It is well known that oxyanions can alter the adsorption behavior of trace metals through cooperative adsorption or competitive effects.However,the specific co-adsorption mechanisms are not yet fully understood.In this study,the adsorption behavior of cadmium(Cd(II))on synthetic lepidocrocite(Lep)in the presence of phosphate was investigated using macroscopic adsorption experiments,in-situ attenuated total reflectance Fourier-transform infrared spectroscopy(ATR-FTIR),and X-ray photoelectron spectroscopy(XPS).The isothermal adsorption experiment results showed that in the absence of phosphate,the adsorption capacity of Lep for Cd(II)was 1.91 mg·g^(-1)with an initial Cd(II)concentration of 1 mmol·L^(-1).When the molar ratios of phosphate to Cd(II)were 1∶1 and 2∶1,the adsorption capacity of Lep for Cd(II)increased by 3.67 times and 16.62 times,respectively,compared to the absence of phosphate;however,when the molar ratio of phosphate to Cd(II)was 5∶1,the adsorption capacity of Lep for Cd(II)only increased by 12.93 times.Adsorption edge results demonstrated that pH had little effect on the phosphate-mediated adsorption behavior of Lep for Cd(II),likely due to the strong coordination ability of phosphate.XPS and ATR-FTIR analyses indicated that Cd(II)can complex with phosphate on the surface of Lep to form ternary complexes(Cd(II)-phosphate-Lep),with phosphate primarily binding to the Lep surface through inner-sphere complexation.Moreover,2D-COS analysis revealed the formation of multiple configurations of phosphate-Cd(II)-Lep ternary complexes on the Lep surface,including bidentate binuclear and monodentate binuclear complexes.These complex configurations are typical models of synergistic adsorption of phosphates and Cd(II)on the Lep surface through the formation of ternary complexes.

关 键 词：镉 磷酸盐 纤铁矿 表面络合结构 界面反应 

分 类 号：X131.3[环境科学与工程—环境科学]