硅/铝掺杂纤铁矿的表面性质及对F^-的吸附性能  

The surface properties and adsorption performance for F^- of Si-or Al-doped lepidocrocite

作　　者：方敦 王锐 许海娟 魏世勇 FANG Dun;WANG Rui;XU Haijuan;WEI Shiyong(College of Resources and Environment,Huazhong Agricultural University,Wuhan Hubei 430070;Department of Chemistry and Environmental Engineering,Hubei Minzu University,Enshi Hubei 445000)

机构地区：[1]华中农业大学资源与环境学院,湖北武汉430070 [2]湖北民族大学化学与环境工程学院,湖北恩施445000

出　　处：《环境污染与防治》2020年第3期287-292,共6页Environmental Pollution & Control

基　　金：国家自然科学基金资助项目(No.41561053)

摘　　要：纤铁矿是土壤中重要的活性矿物组分,常与硅、铝元素共存,对土壤污染物的迁移有重要的影响。采用氧化水解法制备了不掺杂和硅、铝掺杂的纤铁矿(分别记为Lep、Si-Lep、Al-Lep),通过X-射线衍射(XRD)、扫描电镜(SEM)、N2吸附/脱附、质子电位滴定等方法对样品进行表征和表面性质分析,并研究了3种样品对F^-的吸附性能。结果表明:与Lep相比,Si-Lep、Al-Lep的结晶度降低且铝掺杂显著抑制了纤铁矿向针铁矿转化。Lep、Si-Lep和Al-Lep的BET比表面积分别为25.37、28.18、32.51 m^2/g,孔体积、平均孔径和表面分形度均依次增大。Lep、Si-Lep和Al-Lep样品的电荷零点(pH PZC)依次为7.10、6.80、6.50;3种样品的表面羟基密度分别为0.33、0.32、0.36 mmol/g。Lep、Si-Lep和Al-Lep对F^-的最大吸附量分别为6.58、7.32、9.88 mg/g;与Lep相比,Si-Lep和Al-Lep对F^-的准二级动力学速率常数分别降低至0.013、0.014 g/(mg·min);Si-Lep对F^-的吸附亲和力增大,而Al-Lep对F^-的吸附亲和力降低。Lepidocrocite is an important active mineral constituent in soil environment,which always co-exists with Si and Al,and affects the migration of contaminants.In this study,non-doped,Si-doped(Si-)and Al-doped(Al-)lepidocrocite(Lep)were synthesized by oxidative hydrolysis.The structure and surface properties of samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),N 2 adsorption/desorption and proton potential titration.The adsorption performance for F^-on the samples were determined.The results showed that Si and Al doping reduced the crystallinity of lepidocrocite and Al doping significantly inhibited the transformation of lepidocrocite into goethite.The BET specific surface areas of Lep,Si-Lep and Al-Lep were 25.37,28.18 and 32.51 m^2/g,respectively;and the pore volumes,average pore size and surface fractal dimensions of Lep,Si-Lep and Al-Lep increased successively.The points of zero charge(pH PZC)were 7.10,6.80 and 6.50 and the densities of surface hydroxyl were 0.33,0.32 and 0.36 mmol/g for Lep,Si-Lep and Al-Lep,respectively.Adsorption experiments indicated that the maximum adsorption capacities of F^-on Lep,Si-Lep and Al-Lep were 6.58,7.32 and 9.88 mg/g,respectively.In comparison to Lep,the adsorption rate constant of pseudo-second-order kinetics of F^-on Si-Lep and Al-Lep decreased to 0.013 and 0.014 g/(mg·min);the adsorption affinity of F^-increased on Si-Lep,however,decreased on Al-Lep.

关 键 词：纤铁矿 硅 铝 掺杂 吸附 F^- 

分 类 号：X52[环境科学与工程—环境工程]