Fe(II)改性蒙脱石对土壤汞的吸附固定机理探究  

Investigation of the adsorption and immobilization mechanism of Fe(II)-modified montmorillonite on soil mercury

作　　者：周细霞 刘朝淑 孙荣国[2] ZHOU Xixia;LIU Chaoshu;SUN Rongguo(School of Chemistry and Materials Science,Guizhou Normal University,Guiyang,Guizhou 550025,China;Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection,Guizhou Normal University,Guiyang,Guizhou 550025,China)

机构地区：[1]贵州师范大学化学与材料科学学院,贵州贵阳550025 [2]贵州师范大学贵州省山地环境信息与生态保护重点实验室,贵州贵阳550025

出　　处：《贵州师范大学学报（自然科学版）》2024年第4期63-74,共12页Journal of Guizhou Normal University：Natural Sciences

基　　金：国家自然科学基金地区基金项目(42067025);贵州省科技厅科学技术基金重点项目(黔科合基础[2020]1Z038)。

摘　　要：为明确Fe-MMT对土壤汞离子(Hg^(2+))的吸附、解吸特性及潜在作用机理,采用FeSO_(4)·7H_(2)O改性钠基蒙脱土(Na-MMT),合成了Fe(II)基蒙脱石(Fe-MMT),并探究了不同pH值、吸附剂用量、Hg^(2+)初始浓度和反应时间等条件下,Fe-MMT对土壤Hg^(2+)的吸附解吸特性、吸附动力学和等温吸附模型。结果发现:在pH=5、吸附剂用量为0.5 g、Hg^(2+)初始浓度为170 mg/L、反应时间为0.5 h的条件下,Fe-MMT对土壤Hg^(2+)的去除率高达76.8%;Fe-MMT对Hg^(2+)+的吸附过程符合Langmuir等温吸附模型,伪二阶动力学模型可较好地拟合吸附动力学行为,表明该吸附过程主要为单分子层吸附,且主要发生在吸附剂表面的均相反应位点上;结合微观结构表征,发现Fe-MMT对土壤Hg^(2+)的吸附主要通过-S^(2-)、-SH和-OH与Hg^(2+)进行络合,以及Fe^(2+)与Hg^(2+)的原位共沉淀络合引起的;Fe-MMT在水-土混合体系中的解吸率为9.7%,表明Fe-MMT对土壤Hg^(2+)具有较强的固定作用。可见,Fe-MMT具有修复Hg污染土壤的潜力。In order to clarify the adsorption,desorption characteristics and the potential mechanism of Fe-MMT on soil mercury ions(Hg^(2+)),Fe(II)-based montmorillonite(Fe-MMT)was synthesized by modifying sodium-based montmorillonite(Na-MMT)with FeSO_(4)·7H_(2)O to investigate the adsorption and desorption characteristics,adsorption kinetics and isothermal adsorption modeling of soil Hg^(2+)with Fe-MMT under the conditions of different pH values,adsorbent dosages,initial Hg^(2+)concentrations,and reaction time.It was found that Fe-MMT removed up to 76.8%of soil Hg^(2+)at pH=5,adsorbent dosage of 0.5 g,initial Hg^(2+)concentration of 170 mg/L and reaction time of 0.5 h.The adsorption process of Fe-MMT on Hg^(2+)was consistent with the Langmuir isothermal adsorption model,and the pseudo-second-order kinetic model could fit the adsorption kinetic behavior well,indicating that the adsorption process was mainly monomolecular layer adsorption and mainly occurs on the homogeneous reaction sites on the adsorbent surface.Combined with microstructural characterization,it was found that the adsorption of soil Hg^(2+)by Fe-MMT was mainly induced by the complexation of-S^(2-),-SH and-OH with Hg^(2+),and the in situ co-precipitation complexation of Fe^(2+)with Hg^(2+).The desorption rate of Fe-MMT in the water-soil mixed system was 9.7%,indicating that Fe-MMT had an excellent immobilization effect on soil Hg 2+.It can be seen that Fe MMT has the potential to remediate soil contaminated with Hg.

关 键 词：吸附 水土混合 解吸 Fe(II)改性蒙脱石(Fe-MMT) 汞 

分 类 号：P579[天文地球—矿物学] X5[天文地球—地质学]