软模板法制备三维花状MgAl-LDH及其吸附性能

采用软模板法,以十二烷基硫酸钠(SDS)为模板剂,经水热合成制得三维花状双金属(Mg Al)氢氧化物(3D-Mg Al LDH)。通过XRD、FT-IR、SEM及TEM等表征手段,研究了原料Mg/Al物质的量之比、SDS浓度及反应时间对产物微观结构和表面形貌的影响规律,并初步探讨了3D-Mg Al LDH的形成机理。结果表明,当n_(Mg)/n_(Al)=2,SDS浓度为0.1 mol·L~(-1),水热反应时间为6 h时,可形成结晶度良好、花球形貌完整,纳米片厚度均一的三维花状LDH。在3D-Mg Al LDH的形成过程中,SDS既以阴离子形态参与LDH形成,又因其类球状胶束特性附着在已形成的LDH表面或边缘诱导LDH纳米片交叉生长形成三维花状。吸附实验表明,3D-Mg Al LDH对非离子型有机污染物具有良好的吸附作用,最大吸附量约为31 mg·g~(-1),去除率达到100%。

Preparation by Using Soft Template and Adsorption Properties of Three-Dimensional Flower-like MgAl-LDH

Three-dimensional flower-like LDH (3D-MgAl LDH) microspheres were successfully synthesized via hydrothermal method. The sodium dodecylsulfate was used as soft template. The effect of Mg/Al mole ratio, the concentration of SDS and the reaction time on the crystallinity, composition and morphology of 3D-MgAl LDH were investigated by XRD, FT-IR, SEM and TEM. The results show that the optimal condition for uniform 3D-MgAl LDH microspheres with high crystallinity, regular flower-like morphology and thickness uniformity of nanosheets are as follows, n_Mg/n_Al=2, the concentration of SDS was 0.1 mol·L^-1, and reaction time of 6 h. In addition, the growth mechanism of 3D-MgAl LDH was also inferred, SDS was used for intercalated anion to form LDH as well as could form micelles that bond to the outside surfaces and plate edges of LDH, which induced LDH nanosheet cross-growth. Finally, the adsorption activity present that 3D-MgAl LDH exhibits great adsorption capacity of ca. 30 mg·g^-1 for naphthalene and the removal rate of 100%.