Fly Ash Based Magnetic And Catalytic Functional Materials:Preparation And Water Treatment Application

Fly ash（FA）is the fine particulate matter captured in the flue gas produced after coal combustion.It is one of the large industrial wastes currently stored.The large accumulation of fly ash causes great pollution to the environment,and its effective disposal has attracted widespread attention.Fly ash has good stability and porous structure.It is often used as a good adsorption material in the fields of dye and heavy metal adsorption,soil improvement and other fields.In recent years,the functional utilization of fly ash has further promoted the development of its treatment and comprehensive utilization.The composite material obtained by combining fly ash and functional nanomaterials is one of the important ways for the functional utilization of fly ash.However,the existing functionalization methods have problems such as poor controllability of the composite process and poor structural stability of the prepared composite materials.Metal organic framework materials（MOFs）are functional materials connected by metal ions and organic molecules through coordination,presenting a network structure.They have an ordered pore structure and a large specific surface area.They can form metals oxide porous carbon materials under pyrolysis conditions.It is effective precursor materials for the preparation of new inorganic functional materials.In this paper,the composite of FA and functional nanomaterials was successfully prepared by pyrolyzing the composite of FA and MOF,and the functionalization of FA was realized.The obtained material has good controllability,stable structure and good application characteristics.The thesis specifically realized the preparation of magnetic fly ash and fly ash photocatalytic materials.While systematically researching and analyzing the structure and components of the prepared materials,the application characteristics of dye wastewater treatment were studied and explored.The main research contents are as follows:First,the basic characteristics of fly ash,modification methods,and the research progress of fly ash adsorbents are briefly introduced.At the same time,the characteristics,synthesis methods and application of MOF materials are briefly summarized;then the dye wastewater is briefly described.It also briefly introduces the research progress of magnetic adsorption materials,photocatalytic materials and fly ash-based adsorbents in dye wastewater treatment.Finally,the idea of this thesis is proposed.That is,MOF materials are loaded on the surface of industrial waste fly ash,and through calcination and pyrolysis treatment,two fly ash functional materials,FA@Fe₃O₄ and FA@ZnO,can be controlled and synthesized,and they can be used in the treatment of dye wastewater.While improving the comprehensive utilization efficiency of fly ash,it also provides new ideas for the recovery and treatment of fly ash.Secondly,the FA@Fe₃O₄ functional material is obtained by loading the iron-based MOF material MIL-88B-NH₂ on the surface of FA,and further calcining and pyrolyzing it to obtain the FA@Fe₃O₄ functional material.The synergistic effect of FA and Fe₃O₄ porous carbon material realizes the controllable preparation of the magnetic fly ash functional material.Make full use of the magnetic and adsorption properties of Fe₃O₄ porous carbon materials.The structure,composition and performance of the obtained FA@Fe₃O₄functional material were systematically analyzed and studied.The results showed that the prepared composite was stably composited by FA and Fe₃O₄,and had a large specific surface area and magnetic separation characteristics;The best preparation conditions are:FA:MIL-88B-NH₂=1:5,and the calcination temperature is 600℃.The results of the methylene blue simulated dye wastewater adsorption experiment show that the composite material has excellent adsorption performance,with an adsorption rate of over 98%.The adsorption process conforms to the Langmuir isotherm model in terms of thermodynamics,and is closer to the pseudo first-order reaction process in terms of kinetics.Material recycling efficiency is high,and it has certain application value in dye wastewater treatment.Then,by loading the zinc-based MOF material ZIF8 on the surface of FA,and through the high-temperature pyrolysis reaction,the FA@ZnO photocatalytic material was successfully prepared under controllable conditions.The presence of FA can increase the concentration of pollutants on the surface of the composite material,so that the photocatalytic performance provided by ZnO can be maximized.Similar to the previous method,the study analyzed the influence of the loading of MOFs on the structure and functional properties of the obtained materials,and further conducted a systematic analysis of the structure,composition and characteristics of the photocatalytic degradation of dyes in wastewater.The results show that the FA@ZnO photocatalytic material prepared by this method has photocatalytic properties,has good structural stability and at the same time increases the specific surface area,and exhibits good dye photodegradation performance.It has potential value in environmental governance and the functionalization of fly ash.Finally,on the basis of summarizing the characteristics of the MOF-loaded fly ash functionalized preparation method and the results of the topic selection experiment.The research and development prospects of fly ash-based functional materials in preparation methods,structure and component analysis,performance research and application development are prospected.