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研究报告

覃建娴,余芳,陈元涛,张炜,马文清,许成,刘蓉.CoZn-ZIF/MgAl-LDHs制备及其对碘吸附性能的研究[J].环境科学学报,2019,39(2):410-416

Synthesis and adsorption of performance for iodion of CoZn-ZIF/MgAl-LDHs composite materials

摘要：通过在双金属氢氧化物MgAl-LDHs表面定向固定纳米尺度的CoZn-ZIF，并原位生长形成CoZn-ZIF/MgAl-LDHs复合材料.利用扫描电子显微镜（SEM），傅里叶变换红外光谱仪（FT-IR），X射线衍射（XRD）和热重差热综合热分析仪（TGA/DSC）分析手段对材料进行表征，考察CoZn-ZIF/MgAl-LDHs复合材料对正己烷中碘分子的吸附行为，讨论了吸附时间和吸附温度对吸附性能的影响.此外，还对吸附过程的吸附动力学和热力学进行详细的研究，考察准一级和准二级动力学模型，Langmuir和Freundlich等温吸附模型探究该材料的吸附机理.实验结果表明，CoZn-ZIF/MgAl-LDHs对碘的吸附行为符合准二级动力学模型，吸附平衡时间为225 min.通过Langmuir等温方程得到最大平衡吸附量为344.3322 mg·g^-1，碘的吸附过程更好地拟合Freundlich等温方程，说明反应是多分子层吸附过程，同时，由热力学数据得知该吸附是以物理吸附为主的放热过程，降低温度对吸附过程更有利.

Abstract：Here, CoZn-ZIF/MgAl-LDHs was prepared through in-situ growth and CoZn-ZIF materials were directly immobilized on layered double hydroxides MgAl-LDHs. The characteristics of the materials were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetry analysis/differential scanning calorimetry(TGA/DSC) analysis methods. To study the adsorption performance of CoZn-ZIF/MgAl-LDHs on iodine in n-hexane solution, the effect of adsorption time and temperature on adsorption performance were discussed. In addition, the adsorption kinetics and thermodynamics of the process were also studied in detail. The experimental results showed that the adsorption behavior of CoZn-ZIF/MgAl-LDHs for iodine were found to follow the pseudo-second-order kinetic model, and the adsorption equilibrium time was 225 min. The maximum equilibrium adsorption capacity was 344.3322 mg·g^-1 by fitting the experimental data with the Langmuir isotherm equation. The adsorption process fitted the Freundlich isothermal equation better, indicating that the reaction was a multi-layer adsorption process. And it is known from the thermodynamic data that the adsorption is an exothermic process dominated by physical adsorption, adsorption capacity of iodine increased with temperature decreasing.