金属有机骨架MIL-68(Al)对水中典型荧光增白剂VBL的吸附去除

以金属有机骨架材料MIL-68(Al)为吸附剂,探究其对水中典型荧光增白剂VBL分子的吸附行为.采用粉末X射线衍射仪(XRD)、傅里叶变换红外光谱(FTIR)、场发射扫描电镜(SEM)及N_2吸附脱附对MIL-68(Al)的结构性质进行表征.探讨了p H值、离子强度、污染物初始浓度、反应温度及吸附时间对MIL-68(Al)吸附去除水中VBL的影响,并对吸附等温线、动力学、热力学及吸附机制进行了分析.实验结果表明,MIL-68(Al)对VBL的吸附能适应较宽的p H范围,吸附等温线符合Langmuir模型,最大吸附容量达到400.02 mg·g~(-1);吸附速率在前20 min很快,并且能在180 min达到吸附平衡,吸附动力学符合准二级动力学模型;吸附过程是吸热反应,吸附自发进行并且主要由熵驱动;静电作用和氢键作用对吸附均有贡献,静电作用是吸附发生的主要机制.由以上结果可知,MIL-68(Al)是一种潜在的高效吸附剂,在去除水中的VBL分子方面极具潜力.

Adsorption removal of fluorescent whitening agent VBL onto a metal organic framework, MIL-68(Al)

MIL-68(Al), a metal organic framework, was synthesized and used to explore its adsorption behavior toward fluorescent whitening agent VBL.The adsorbent was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and N₂ adsorption-desorption. The adsorption isotherm, kinetics, thermodynamics, adsorption mechanism and some key operating factors, such as pH, ionic strength, temperature, initial concentration, adsorption time, were investigated. The results showed that MIL-68(Al) could be used over a wide pH range to remove VBL. The adsorption isotherm follows the Langmuir isotherm model with a maximum equilibrium adsorption capacity of 400.02 mg·g^-1. Adsorption rate was fast in the first 20 min and reached equilibrium within 180 min, the adsorption process was more suitably described by a pseudo-second-order model. Thermodynamic data demonstrated that the adsorption process was spontaneous, endothermic and mainly driven by entropy. Electrostatic and hydrogen bonding interactions contributed to VBL adsorption, and electrostatic interactions were considered to be the principal binding force between adsorbent and adsorbate. From these results, MIL-68(Al) was proved to be a promising adsorbent for removing VBL from aqueous solution.