镁铝二元水滑石焙烧产物对酸性紫90染料的吸附性能(英文)

Adsorption Characteristics of Calcined Layered Double Hydroxides over Acid Violet 90

研究了镁铝比为3:1的二元水滑石(layered double hydroxides)焙烧产物(MgAl–LDO,layered double oxide)对弱酸性染料酸性紫90(C40H27CrN8Na2O10S2,AV90)的吸附性能。X射线衍射和Fourier变换红外光谱的结果显示:由于水滑石的"结构记忆效应",在富水条件下,MgAl–LDO会吸附部分AV90阴离子进入水滑石层间,从而恢复为层状结构的MgAl–LDHs。研究结果表明:MgAl–LDO对AV90具有良好的去除效果,在298 K,pH=9.7条件下,MgAl–LDO对AV90去除率高达99.7%,吸附容量为999.78 mg/g。MgAl–LDO对AV90的吸附过程同时符合Langmuir和Freundlich等温吸附方程,并且是一个自发、放热的过程。动力学研究表明:该吸附动力学符合准二级动力学模型。吸附实验结果同时表明:MgAl–LDO吸附性能优于活性炭和二氧化硅等传统吸附剂,经三次回收利用的MgAl–LDO对AV90仍具有良好的吸附性能。

The adsorption characteristics of calcined layered double hydroxides with a Mg to Al mole ratio of 3：1（MgAl–LDO,lay-ered double oxide） were investigated to remove a weak acid dye acid violet 90（C40H27CrN8Na2O10S2,AV90）.In the light of ＂memory effect＂,MgAl–LDO is able to recover their original layered structure in an aquatic environment,after adsorption part of AV90 and CO32–（come from air） intercalated into interlayer of MgAl–LDHs,its structure was confirmed by X-ray diffraction and Fourier trans-form infrared spectra.The results of adsorption experiments indicate that the MgAl–LDO has a significant ability to remove AV90（500 mg？L–1） from the solution.The maximum equilibrium capacity Qe and removal rate η of AV90 are 999.78 mg/g and 99.7%,respectively.Adsorption isotherms show that the adsorption process is consistent with both Langmuir and Freundlich equations which is also spontaneous and exothermic.The kinetic model has been evaluated to fit the experimental data,and it is found that the pseudo-second-order best describes the adsorption kinetics of MgAl–LDO to AV90.In addition,adsorption of MgAl–LDO is higher than activated carbon,SiO2 and other traditional adsorbents.The regeneration for reuse of LDO after AV90 adsorption is feasible at least three cycles.