| Remarkable progresses on metal-organic frameworks (MOFs) have been achieved in recent years, which is due to the huge porosity and easy tunability of their pore size and shape by changing the connectivity of the inorganic moiety and the nature of the organic linkers, and their potential applications in gas storage, gas adsorption and separation, catalysis, sensing, and magnetic.Although some traditional techniques, such as solution diffusion techniques or slow vapour, solvothermal methods and hydrothermal, are applied to prepare MOFs and nanoscale MOFs. However, traditional methods for synthesis of this type of porous frameworks often should undertake drawbacks such as long reaction time, high boiling-point solvents and high pressure, which not only makes the synthetic process boring, dangerous and cumbersome, but also causes a great waste of energy. The syntheses of MOF-type materials have been studied widely not only for searching simple and facile methods but also for finding new structures. Such as microwave (MW) and ultrasound (US) synthesis.In this work, we illustrate highly efficient synthesis of nanoscale MIL-101(Cr) crystals using a templated hydrothermal method. The results suggest that such a novel kind of templated hydrothermal synthesis route is a highly time-and energy-efficient method for synthesizing nanoscaled MIL-101(Cr) crystals with controllable sizes. And further MOFs based magnetic composite materials was prepared, and study the application of this material in the organic dye adsorption.The main contents of this thesis are as follows:1. The objective of this content is to describe a very rapid way for Expanded graphite (EG)-assisted synthesis of MIL-101(Cr) that allows the prepared to be completed in2hours. The structures were confirmed by scanning electron microscopy (SEM), transmission electron microscope (TEM), powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET). This synthesis method can increase nuclei growth compared with the traditional synthesis method, and show a much high speed of reaction. The size of MIL-101(Cr) crystals from micro-scale to nano-scale, where the EG acts as the nucleation template. This may have significant effect on the template-directed nucleation and crystallization of crystals. The reaction time was shortened greatly by adopting this synthesis method.2. EG as a template template method can greatly shorten the reaction time, but the preparation of the MIL-101(Cr) crystal clean after remain extremely small amount of EG crystals. In order to repid synthesis pure MIL-101(Cr), we choose pure MIL-101(Cr) as seed crystal to synthesis MIL-101(Cr) hydrothermal method, also can greatly shorten the reaction time. The structures were confirmed by PXRD, SEM, TEM and BET, and explore the optimal process conditions.3. MIL-101(Cr) as a novel kind of efficient absorbent for removal organic dyes from aqueous solution. However, there is a disadvantage that conventional powdery MIL-101(Cr) materials are difficult to be separated and recovered except by high speed centrifugation and filter of MOF materials baffling its practical applications. Herein, we rep ort, for the first time, a novel kind of magnetic biomaterial that composes of chitosan enwrapping nanosized Fe3O4and various weight contents of MIL-101(m-CS/Fe3O4/MIL-101). The as-prepared m-CS/Fe3O4/MIL-101composites were characterized by PXRD, BET, SEM, TEM and vibrating sample magnetometer (VSM). Methyl orange (MO) with large and complicated structures was selected as model pollutant to examine adsorption kinetics and thermodynamics of pollutant onto the m-CS/Fe3O4/MIL-101composite under different experimental conditions. The results suggest that these magnetic composites exhibit excellent adsorption capacity and rapid adsorption kinetics, as well as a perfect magnetic separation performance, for the removal of MO from aqueous solution. This information may be useful not only for further research and practical applications of the novel magnetic bioadsorbent in dyeing wastewater treatment. |
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