Mn(Ⅱ)在针铁矿表面催化氧化对Cd吸附固定的影响  

Effect of catalytic oxidation of Mn(II)on the adsorption and the immobilization of Cd by goethite

作　　者：张家伟 郭楚玲 邓燕萍 徐子冉 王超平 周玉婷 陈锴 党志 ZHANG Jiawei;GUO Chuling;DENG Yanping;XU Ziran;WANG Chaoping;ZHOU Yuting;CHEN Kai;DANG Zhi(The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters,Ministry of Education,School of Environment and Energy,South China University of Technology,Guangzhou 510006)

机构地区：[1]华南理工大学环境与能源学院,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

出　　处：《环境科学学报》2024年第10期344-353,共10页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.41931288);国家重点研究计划项目(No.2023YFC3207304)。

摘　　要：针铁矿在环境中广泛存在且在固定潜在有毒元素方面发挥着关键作用.同时,光照与光反应性元素(例如Mn(Ⅱ))的存在同样会影响潜在毒害元素的迁移与归趋.本研究探究了光照条件下,Mn(Ⅱ)共存对针铁矿表面吸附Cd的影响.研究发现,Mn(Ⅱ)在针铁矿表面光催化氧化为Mn(Ⅲ/Ⅳ),部分Mn(Ⅱ/Ⅲ)掺杂进针铁矿结构中.SR-XRD数据精修表明,Mn的掺杂量越大,针铁矿晶胞结构变化越显著.FTIR和拉曼光谱证实了Mn(Ⅱ/Ⅲ)掺入会导致针铁矿结构的畸变以及表面羟基位点含量的增加.同时,Mn(Ⅱ)的氧化使针铁矿表面电荷由正变为负.羟基位点的增加与表面电荷变负均增强了针铁矿对Cd的吸附能力.但Mn(Ⅱ)初始浓度过高(超过0.2 mmol·L^(-1))时,Mn(Ⅱ)的竞争吸附以及Mn(Ⅲ)氧化物占比的升高都会降低Cd的固定量.本研究揭示了Mn(Ⅱ)对Cd在针铁矿上固定的影响机制,为利用铁锰氧化物修复Cd污染土壤提供了理论依据.Goethite is widely distributed in the environment and plays a key role in the immobilization of potentially toxic elements(PTEs).Meanwhile,light and photoreactive elements(e.g.,Mn)can also affect the transport and fate of PTEs.This study investigated how the coexistence of Mn(II)impact on the adsorption of Cd on the goethite surface under light conditions.Our results demonstrated that Mn(II)was photocatalytically oxidized to Mn(III/IV)on the goethite surface,with partial Mn(II/III)being incorporated into the goethite structure.Refinement of the SR-XRD data showed that higher Mn(II)concentrations resulted in increased levels of Mn doping,leading to significant variations in the goethite unit cell.FTIR and Raman spectra confirmed the distortion of the structure of goethite and the enhancement of hydroxyl sites on the surface of goethite.Additionally,the oxidation of Mn(II)changes the surface charge of goethite from positive to negative.The increase in hydroxyl sites and the negative surface charge both enhanced the adsorption capacity of goethite for Cd.However,when the initial concentration of Mn(II)exceeded 0.2 mmol·L^(-1),both the competitive adsorption of Mn(II)and the increase in the proportion of Mn(III)oxides decreased the adsorption amount of Cd.This study reveals the mechanism of Mn(II)influence on Cd immobilization on goethite and provides a theoretical basis for the remediation of Cd-contaminated soil using Fe-Mn oxides.

关 键 词：针铁矿 光催化 Mn(Ⅱ) 镉 吸附和固定 

分 类 号：X131[环境科学与工程—环境科学]