| Volatile organic compounds are one of the important sources of pollution that cause air pollution.In history,VOCs have caused many global environmental crises,which have greatly damaged the ecological environment and seriously threatened human survival.Therefore,the research focus of environmental researchers has gradually been on how to develop efficient scientific and technological methods to deal with VOCs in the atmosphere.Styrene is an important kind of aromatic chemical,widely utilized in synthetic rubber,plastics,polyesters and resins,etc.However,due to its high volatility,styrene would inevitably discharge into the atmosphere and bring a lot of adverse effects on both humans and ecosystems.Thus,styrene,one of representative VOCs,was chosen as a research object.The adsorption method is recognized as a promising VOCs treatment technology because of its low energy consumption,simple operation,and mature process,and it can recover the adsorbed VOCs through desorption and at the same time achieve the purpose of adsorbent recycling.Among the many adsorbents that have been developed,MOFs have received extensive attention from researchers due to their large specific surface area and strong stability.However,how to effectively desorb the adsorbed VOCs and realize the regeneration of the MOFs-based adsorbent is still an urgent problem to be solved at present.In this thesis,a typical MOF material Ui O-66 was used as the carrier,and Ag nanoparticles were deposited on Ui O-66 by the colloidal deposition method to prepare Ag/Ui O-66 composite materials,and explored Ag loading,surface acidity,pores The effect of surface physical and chemical properties such as structure on the adsorption capacity,regeneration capacity,adsorption and desorption kinetics and desorption activation energy of styrene further reveals the regeneration mechanism of Ag/Ui O-66 adsorbent photothermal desorption of styrene.The main contents of this paper are as follows:1)Preparation of Ag/Ui O-66 composite material.Using the typical zirconium-based MOF material Ui O-66 as the carrier,the PVP-modified Ag2+was reduced to Ag nanoparticles by using sodium borohydride by colloidal deposition,and then deposited on Ui O-66 to obtain the Ag/Ui O-66 composite material.Through X-ray diffractometer,transmission electron microscope,ultraviolet spectrophotometer and other characterization methods,the physical and chemical properties of the composite material,such as phase composition,morphology structure,and light absorption range,were analyzed.The research results show that the introduction of Ag nanoparticles did not destroy the morphology and structure of Ui O-66,and because of the plasmon resonance characteristics of Ag nanoparticles in the visible light region,the light absorption range of Ui O-66 was significantly expanded and improved.The light absorption intensity,and the surface temperature of the Ag/Ui O-66 composite material has been greatly increased under light conditions.2)Study on the performance of Ag/Ui O-66 composite material adsorption and photothermal desorption of styrene.The typical VOCs styrene was selected as the research object,and the self-made continuous flow fixed bed light absorption and desorption system was used to investigate the adsorption performance and photothermal regeneration performance of Ui O-66 and Ag/Ui O-66.The research results show that with the increase of Ag nanoparticles loading,the adsorption capacity of Ag/Ui O-66 to styrene decreases,but the light desorption capacity and regeneration efficiency are significantly improved.Ag/Ui O-66with an Ag loading of 2 wt%shows the best comprehensive performance of adsorption and photothermal regeneration.Under the same desorption conditions,its styrene desorption capacity is 5 times that of pure Ui O-66.3)Exploration of the regeneration mechanism of Ag/Ui O-66 composite material photothermal desorption of styrene.Using temperature programmed desorption experiment,surface acid site test,in-situ diffuse reflectance infrared spectroscopy technology and infrared thermal imager,the desorption activation energy of styrene on the composite material,the type of acid site on the adsorbent,and the amount of acid were obtained.During the adsorption process,the adsorption configuration of styrene on the adsorbent,the change of the surface temperature of the material under light,and other information were obtained.Based on the above research results,it is revealed that the uniform dispersion of Ag on the surface of Ui O-66 is conducive to efficient conversion of light energy into heat energy,and rapid desorption of styrene adsorbed on Ag/Ui O-66,thus exhibiting superior properties Photothermal desorption efficiency and regeneration capacity. |
