锰铝二元水滑石和锰铁铝三元水滑石对U(Ⅵ)的高效去除及其机理研究

Interaction of U(Ⅵ) with MnAl and MnFeAl layered double hydroxides: batch and spectroscopy study

本文采用一步水热法制备了新型低成本的二元水滑石(MnAl-LDHs)和三元水滑石(MnFeAl-LDHs)吸附剂,并利用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线粉末衍射仪(XRD)和X射线光电子能谱(XPS)等微观表征技术分析了材料的物理化学性质,通过静态批示实验和光谱分析研究了U(Ⅵ)在MnAl-LDHs和MnFeAl-LDHs上的吸附行为和相互作用机理.宏观实验结果表明, MnAl-LDHs和MnFeAl-LDHs对U(Ⅵ)的吸附在60 min内都达到了平衡,且在pH=5.0条件下三元MnFeAl-LDHs对U(Ⅵ)呈现出较高的吸附量(157.73 mg/g),是U(Ⅵ)在二元MnAl-LDHs上饱和吸附量(70.72 mg/g)的两倍.此外, MnFeAl-LDHs在高盐度、复杂共存离子环境下和不同水体系中依然表现出优越的吸附性能. FTIR和XPS光谱分析结果表明, U(Ⅵ)不仅可以与材料表面的–OH和层间CO32-形成较强的络合,还能与水滑石中的部分Mn^(2+)发生取代反应.本文的研究揭示了含锰水滑石材料在高效修复放射性废水中的吸附机理和潜在的应用前景.

Herein,the binary and ternary layered double hydroxides(MnAl-LDHs and MnFeAl-LDHs)were synthesized using a one-pot hydrothermal method for efficient adsorption of U(VI),and characterized by SEM,FTIR,XRD and XPS technologies in detail.The removal mechanism of U(VI)on LDHs was investigated by batch experiments and collective spectroscopy characterizations.The results showed that MnAl-LDHs and MnFeAl-LDHs exhibited rapidly binding U(VI)within 60 min and large adsorption capacity(70.72 mg/g for MnAl-LDHs and 157.73 mg/g for MnFeAl-LDHs)at pH=5.0,which were superior to those LDHs-based adsorbents in previous literatures.In addition,the great uptake performance could be maintained with various relevant interferences.The adsorption of U(VI)on LDHs was controlled by inner-sphere surface complexation or ions substitution,which was confirmed by spectroscopic analysis.This article revealed the great potential of manganese-containing LDHs in the remediation of real nuclear wastewater.