具有染料选择吸附性的衍生于沸石咪唑酯骨架-67的NiCo-层状双氢氧化物设计与合成

Designed Formation of NiCo-Layered Double Hydroxide Derived from Zeolitic Imidazolate Framework-67 with Selective Dye Adsorption Property

以沸石咪唑类金属有机骨架(ZIF-67)为模板合成了一种新型的中空吸附剂NiCo-LDH@ZIF-67,该吸附剂对甲基橙具有良好的选择吸附性以及可循环性。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)、红外光谱、电子能谱和氮气吸附-脱附等手段对样品进行了表征。研究了溶液的pH值、甲基橙的初始浓度以及染料与吸附剂作用时间对NiCo-LDH@ZIF-67吸附性能的影响。结果表明,该吸附剂对甲基橙的吸附动力学符合准二级动力学模型,且吸附等温线符合朗缪尔方程。当pH值等于4,吸附时间15 min,吸附剂用量为2400 mg/L时,该吸附剂对甲基橙的最大吸附量可达1766 mg/g,高于之前文献报道的类似吸附剂。此外,NiCo-LDH@ZIF-67能从甲基橙和亚甲基蓝的混合溶液中选择性吸附甲基橙。

A novel hollow composite of NiCo-layered double hydroxide and zeolitic imidazolate framework-67(NiCo-LDH@ZIF-67)adsorbent with high adsorption capacity for pollutants,high adsorption selectivity of methyl orange(MO)and great regenerability was synthesized using ZIF-67 as a template.The sample was characterized by using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),Fourier transform infrared spectrometer(FT-IR),N 2 adsorption desorption and X-ray photoelectron spectroscopy(XPS).The effect of solution pH,the initial MO concentration and the contact time with the mixture solution on the adsorption property of NiCo-LDH@ZIF-67 was studied.The results indicate that its adsorption kinetics for MO can be well simulated by a pseudo-second-order model and its adsorption isotherm for MO follows the Langmuir equation.The optimized adsorption condition is pH=4,contact time of 15 minutes,and adsorbent dosage of 2400 mg/L.Its maximum adsorption capacity for MO can reach as high as 1766 mg/g and is higher than those reported for all similar adsorbents in the literature.In addition,NiCo-LDH@ZIF-67 can selectively adsorb MO from a mixed solution of MO and methylene blue(MB).