Preparation And Adsorption Application Of Multifunctional Metal-organic Framework Composites

The rapid development of industry has made human beings satisfied materially and spiritually,but problems such as energy depletion,greenhouse effect,and water pollution are becoming more and more serious.In recent years,metal-organic frameworks(MOF)are expected to become a new generation of materials for adsorption separation,fluorescence sensing,and catalysis due to their high specific surface area,controllable pore size,and open metal sites.For example,the use of MOF materials for CO₂ capture and adsorption and identification of metal ions or small organic molecules has become a hot topic in recent years.The stability is poor;the utilization rate and performance of its small and light crystals will be greatly reduced after being added to the polymer for molding,etc.These are important factors restricting its further development.Activated carbon particles(AC)are one of the most widely used porous materials,which have the characteristics of high specific surface area and porosity,stable structure and low cost.Based on its well-developed pore structure,activated carbon has a wide range of applications in industrial fields such as adsorption of harmful gases,air purification,and sewage treatment.However,the application of activated carbon is often limited due to its disordered pore structure and fewer active functional groups.For example,although activated carbon has gas adsorption properties,its selective adsorption capacity for gases is not high;in water treatment,although it can adsorb metal ions and impurities,its ability to identify metal ions is not enough.It is worth mentioning that,due to the macroporous structure of activated carbon,this type of material is suitable for use as a carrier,typically platinum-carbon materials are widely used.Based on the above research and analysis of the current situation,this paper intends to grow MOF materials in situ inside the activated carbon particles to prepare a new type of composite porous materials,and study the selective adsorption of carbon dioxide and the identification of metal ion pollutants in water.application.The specific research contents are as follows:(1)Preparation of ZIF-8@activated carbon composites and research on selective adsorption of carbon dioxide.Under mild conditions,ZIF-8 was grown in situ inside the activated carbon particles.The structure and composition of the composites were characterized.The single-component adsorption isotherms of CO₂,CH₄,and N₂ were further measured at 273 K and 298 K.The CO₂ adsorption capacity of ZIF-8@activated carbon composite was 60.8 cm³ g^-1 and 42.0 cm³ g^-1 at 273 K and 298 K,respectively.Finally,according to the ratio of the initial slope of the Henry zone of the adsorption isotherm,the CO₂/N₂ gas selectivities of the ZIF-8@activated carbon composite were calculated to be 12.49 and 12.03 at 273 K and 298 K,respectively,which was 55%and102%higher than that of activated carbon particles.(2)Preparation of rare earth MOF@activated carbon composites and their selective adsorption and identification of heavy metal ions in aqueous solution.Through in situ synthesis,a series of rare earth MOF@activated carbon composites were prepared,and the structural composition of the materials was characterized.Finally,two composite materials,Tb-MOF@activated carbon and Eu-MOF@activated carbon,were selected to test the performance of metal ion fluorescence sensing.It was found that Tb-MOF@activated carbon composite could recognize Fe³⁺and Cr³⁺in aqueous solution.ions,of which the lowest detection limit of Fe³⁺is 21.3?M;Eu-MOF@activated carbon can recognize Fe³⁺in aqueous solution.At the same time,since only a very low load is required,the cost of using the MOF is reduced.