Preparation Of Functional MIL-101 Type And UIO-66 Type MOFs For The Adsorption Of Dyes, Mercury And Arsenic Form Aqueous Soultion

Environment pollution problems have attracted increasing public concern in china as a result of increasing industrial and urban development. In particular, water courses throughout the industrialized world are polluted with organic dyes and heavy metal emanating from wastewater effluents. Synthetic dyes discharged into the environment have posed a significant environmental and health risk due toxic and potentially carcinogenic nature of these materials. Heavy metal pollution has also become a major environment problem. Metal-organic frameworks(MOFs) have recently emerged as an important family of porous materials due to their high specific surface area and their potential applications in adsorption. Functional metal-organic frameworks were developed in order to solve some problems found in dye and heavy metal adsorption. As the same time, this work can present the prospects of metal-organic frameworks expanded application range. The details are summarized as follows:1. In this work, seven hierarchically mesostructured MIL-101 metal-organic frameworks(MOFs) were synthesized using anhydrous sodium acetate or hydrofluoric acid as the mineralizing agent and cetyltrimethylammonium bromide(CTAB) as a structure-directing agent. These new materials were then used to adsorb and remove the anionic dye methyl orange(MO) and the cationic dye methylene blue(MB) from contaminated water. The adsorption performance was systematically investigated and discussed. Experimental results revealed that using an acid or a base as the mineralizing agent, the basic structure of the MOFs remains the same, but the charge of the framework may be altered. It could affect the dye adsorption properties of the MOFs. Adsorbents synthesized with higher CTAB content had a higher content of the mesoand macro-scale pores, which favored the MB adsorption but impeded the MO adsorption. The MB and MO adsorption kinetics followed a pseudo-second-order model, and the equilibrium dye adsorption data provided a good Langmuir model. Moreover, dye adsorption is an endothermic process.2. In this paper, a novel thymine-functionalized MIL-101(MIL-101-Thymine) material was first synthesized by post-synthesis method for the highly efficient removal of mercury. MIL-101-Thymine was successfully prepared in this work, which was confirmed by several characterization methods, such as X-ray diffraction, 13 C nuclear magnetic resonance, infrared spectroscopy, and Thermogravimetry. The Hg(II) adsorption agreed well to the Langmuir model with the maximum adsorption capacity 51.27 mg/g. The adsorption mechanism of Hg(II) on MIL-101-Thymine is that the Hg(II) coordinated with N of thymine on MIL-101-Thymine forming Thymine-HgThymine structure. The adsorption rate of Hg(II) adsorption fitted pseudo-second-order kinetic model. Furthermore, MIL-101-Thymine exhibited excellent selectivity towards Hg(II) over other cation ions, and the maximum value of selective coefficient reaches 648.29 compared to Ni(II), which dominated by p H value of surroundings with the optimum p H value range of 4-6. It is very likely due to the highly selective thymineHg2+-thymine interactions in MIL-101-Thymine. MIL-101-Thymine is an excellent adsorbing material to remove trace Hg(II) in real wastewater with a outstanding adsorbing efficiency.3. UIO-66 and UIO-66-NH2 were synthesized through solvothermal method and characterized by XRD、BET、IR、Zeta potential. The results shown that Freundlich model is fittable in the adsorption of As(III) on UIO-66 and UIO-66-NH2. The adsorption process is heterogeneous process. While the the As(V) adsorption on UIO-66 and UIO-66-NH2 agreed well to the Langmuir model, the adsorption process is monolayer absorption process. The As(III) adsorption capacity by UIO-66 and UIO-66-NH2 is much more than that of As(V). The maximum value of is reaches 648.29 200.16mg/g by As(III) adsorpted on UIO-66 in around 60 min and fitted pseudo-secondorder kinetic model. The optimum p H value range is 4-6. The coexistence of anion experiment results shown that there existence of antijamming capability in the adsorption of As(III) on UIO-66.