三维有机LDH的制备及其对有机物的普适性吸附

Synthesis of organic 3D flower-like layered double hydroxide and universal adsorption for organic pollutants

以表面活性剂十二烷基硫酸钠(SDS)为软模板剂,制得有机三维花状层状双金属氢氧化物(3D-SLDH).采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱仪(EDS)和N2吸附-脱附等表征手段对3D-SLDH的结构进行表征,确定最佳合成尿素浓度,并通过静态吸附实验考察了3D-SLDH对金橙Ⅱ(AO7)、罗丹明(RhB)以及萘(NAP)的吸附性能.结果表明,室温下,3D-SLDH对AO7、RhB和NAP的吸附容量分别为454.9,46.8和43.7mg/g,表明其对有机物的吸附具有普适性.3D-SLDH对AO7、RhB和NAP吸附过程均符合准二级动力学模型,对AO7和RhB的吸附等温线符合Langmuir模型,而对NAP的等温吸附行为符合partition-adsorption模型.升温有利于3D-SLDH对AO7和RhB的去除,不利于对NAP的去除.此外,结合反应前后固样XRD,FT-IR和XPS分析,可知3D-SLDH对AO7的去除机制主要是层间离子交换作用,对RhB的去除机制主要是疏水及表面吸附作用,而对NAP的去除机制主要为分配作用.

Organic 3D flower-like layered double hydroxide(3D-SLDH)was prepared by sodium dodecyl sulfate(SDS)under various urea concentrations.X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray energy dispersive spectral analysis(EDS),and Brunauer-Emmett-Teller(BET)were employed to determine the optimum synthesis condition.The adsorption performance of 3D-SLDH for acid orange 7(AO7),rhodamine B(RhB),and naphthalene(NAP)was studied by static adsorption experiments.The results showed that the adsorption capacity of 3D-SLDH toward AO7,RhB,and NAP could reach up to 454.9,46.8 and 43.7mg/g,respectively,indicating that 3D-SLDH is a universal adsorbent to organic pollutants.Adsorption kinetics demonstrated that all contaminants removal could be well described by the pseudo-second-order model.The adsorption isotherms of AO7 and RhB fitted the Langmuir model,while partition-adsorption model was suitable for NAP adsorption.Moreover,the elevated temperature benefited for both AO7 and RhB adsorption.By contrast,lower temperature is suitable for NAP removal.Combined with the analysis of XRD,FT-IR,and XPS,the removal mechanism of AO7,RhB and NAP on 3D-SLDH was investigated.Ion exchange and surface adsorption contributed to AO7 and RhB adsorption,respectively.Whereas partition played a dominant role in NAP removal.