镁铁类水滑石的制备、表征及吸附甲基橙的性能  

Preparation,characterization and adsorption behavior of magnesium-iron layered double hydroxides for methyl orange

作　　者：吴永娟[1] 王晓兰[1] 闫俊英 WU Yong-juan;WANG Xiao-lan;YAN Jun-ying(Department of Chemistry and Chemical Engineering,Shaanxi Xueqian Normal University,Xi'an 710100,China;College of chemistry and material science,Hebei Normal University,Shijiazhuang 050086,China)

机构地区：[1]陕西学前师范学院化学与化工系,陕西西安710100 [2]河北师范大学化学与材料学院,河北石家庄050028

出　　处：《化学研究与应用》2019年第4期740-746,共7页Chemical Research and Application

基　　金：国家自然科学基金项目(B070202)资助;陕西省自然科学基金项目(2016JM2018)资助;陕西省教育科学"十三五"规划课题(SGH16H133)资助

摘　　要：采用恒pH沉淀法,以混合碱(NaOH和Na_2CO_3)溶液为沉淀剂,控制反应溶液pH为8.5制得不同镁铁物质的量比(x)的4种类水滑石(Mg_xFe-LDH)。450~oC煅烧Mg_xFe-LDH得到Mg_xFe-cLDH。通过XRD、SEM技术对Mg_xFe-LDH和-cLDH进行了表征。结果显示,Mg_xFe-cLDH颗粒的纯度、分散程度随x的增加呈现先增加后下降的过程。当Mg/Fe物质的量比为2.26,即Mg_(2.26)Fe-cLDH具有理想的纯度和分散程度。以甲基橙(MO)为模拟污染物,研究了Mg/Fe物质的量比、竞争阴离子(OH^-,NO_3^-,Cl^-,SO_4^(2-),CO_3^(2-))、温度对Mg_xFe-cLDH吸附MO的影响。吸附结果表明,Mg_(2.26)Fe-cLDH在Mg_xFe-cLDHs(x=0.98～4.50之间)中具有最大的饱和吸附量(1191.8 mg·g^(-1)),这可能与其具有良好的分散程度有关。竞争阴离子对该吸附无明显影响,表明Mg_(2.26)Fe-cLDH对MO产生选择性吸附。Langmuir方程模拟结果表明该吸附是自发、吸热的化学过程。吸附机理可能是Mg_(2.26)Fe-cLDH与MO之间生成了MO插层超分子化合物。Mg–Fe Layered double hydroxides(Mg x Fe-LDHs)with various Mg-Fe molar ratios were synthesized by simultaneously titrating corresponding mixed salt and alkali solution at pH value of 8.5.Here x is the Mg-Fe molar ratio.Its calcined form(Mg x Fe-cLDH)was obtained by calcinating at 450℃.These materials were characterized by the techniques of XRD and SEM,respectively.The results showed the purity and dispersion degree of Mg x Fe-cLDH displays an increase followed by a decrease as x shifts from 0.98 to 4.50.Mg 2.26 Fe-cLDH has the top purity and dispersion.Taking methyl orange(MO)as a modulate pollutant,the effect of Mg/Fe molar ratios,competitive anions(OH^-,NO 3^-,Cl^-,SO 4^2-,CO 3^2-)and temperature on the adsorption of MO onto Mg x Fe-cLDH was investigated in detail.The adsorption results indicated that Mg 2.26 Fe-cLDH has the top adsorption capacity(1191.8 mg·g^-1)among Mg x Fe-cLDHs(x=0.98~4.50),which may be ascribe to its higher dispersion.Competitive anions have no obvious influence on the present adsorption,which indicated that Mg 2.26 Fe-cLDH is a selective sorption to MO.The results fitted by Langmuir equation illustrated the adsorption was a spontaneous,endothermic and chemical process.The adsorption mechanism may be the formation of MO intercalation compound.

关 键 词：镁铁类水滑石 甲基橙 吸附 机理 

分 类 号：X523[环境科学与工程—环境工程]