Preparation And Application Of Functional Iron Based Metal-organic Frameworks Composite Materials

As a new type of material in the field of nanotechnology,metal-organic framework(MOFs)materials due to its orderly structure,high porosity,large surface area,and etc,have become the focus of current research,which have shown potential application value in the adsorption and separation,gas storage,catalytic oxidation,drug controlled release,chemical sensors and biological applications.However,some inherent shortcomings of MOFs materials greatly limit their applications in more aspects.It has become an effective way to expand the practical application of MOFs to prepare new thin film materials with certain flexibility by combining MOFs with polymer and other materials.On this basis,this thesis aims at the preparation of functional composite films.Based on the structural characteristics of MOFs,a series of mixed matrix films are designed and prepared,and their applications in humidity sensing and dye adsorption are studied.The main content of this thesis is as follows:1.The effects of two different preparation methods on the grain size,microstructure and crystal structure of MIL-88A nanocrystals were comparatively studied.The results show that MOFs nanoparticles with relatively uniform grains and better crystallinity can be obtained by the solvothermal method.The crystal particles obtained by continuous agitation method have low crystallinity and incomplete morphology,with BET surface area up to 281 m~2/g.While the crystal particles obtained by solvothermal method have higher crystallinity and more uniform particle size distribution,but their BET surface area is small,only 46 m~2/g.2.MIL-88A MOFs and thermoplastic polyurethane elastomer(TPU)are combined to design and develop a flexible MOF-based monolayer film actuator with flexible characteristics,which can respond to changes in ambient humidity through reversible self-folding behavior,followed by the ability to quickly return to its original state after heating.The effects of exposure time and the content of MIL-88A crystal particles on the humidity response performance of the composite films were investigated.The experimental results showed that the 60MIL-88A@TPU composite film had the best self-folding response performance and exhibited good cyclic response stability at a relative humidity of 75%RH.It is concluded that the reversible bottom-up crimp of the humidity driver under the condition of humidity change is the result of the interaction between TPU and MIL-88A crystal particles.Due to the special"breathing effect"of MIL-88A crystal particles and the non-uniformity of the vertical gradient distribution of TPU phase in the composite film,the stress caused by the expansion of MIL-88A crystal particles is imbalanced in the longitudinal distribution,resulting in the bottom-up crimping of the composite film.Finally,a unidirectional walking device and a heavy grasping device based on the actuator are demonstrated,which makes the actuator have potential applications in the fields of humidity sensing and micro-robots.3.Based on the low toxicity and respiration effect of MIL-88A crystal particles,the microporous MIL-88A@TPU mixed matrix film was designed and synthesized,and its adsorption removal performance and adsorption mechanism for bromophenol blue dye(BPB)were evaluated.The experimental results show that the microporous film material has good adsorption performance for BPB dye.When the amount of MIL-88A in the film is more than 60 wt.%,the removal rate of BPB dye can reach80%.With the increase of the initial dye concentration,the adsorption capacity of the microporous MIL-88A@TPU mixed matrix film gradually increased(7.9～35.8mg/g),but the removal rate of BPB decreased from 98.2%to 83.1%,and the initial concentration remained unchanged in the range of 40～80 mg/L.The thermodynamic study of the adsorption process showed that the adsorption behavior was typical monomolecular adsorption.The adsorption kinetics results showed that the adsorption process was more likely to be chemical adsorption,and there might be electron sharing or exchange valence electron force between the adsorbent and the adsorbent.In addition,MIL-88A@TPU films with a load of 80 wt.%still maintained high adsorption performance for BPB dye after 6 cycles.Therefore,microporous MIL-88A@TPU hybrid matrix films have a good application prospect in the treatment of dye-polluted wastewater,especially for the treatment of anionic dyes containing sulfonyl groups.