Preparation Of Activated Carbon/Expanded Graphite Composite And Its Adsorption Properties For Ethyl Acetate

The progress of technology has promoted the rapid development of various industries.The chemical organic solvents will inevitably discharge a large number of volatile organic compounds（VOCs）into the air due to the excessive applications of them,thus making air pollution control work more severe.Among them,ethyl acetate,as a common industrial organic raw material,accounts for a large proportion in the annual VOCs emission.The adsorption method as a popular recovery technology has drawn considerable attention because of its simple operation,low energy consumption,and easy automatic control,which is regarded as an effective and economical solution for VOCs treatment.Activated carbon is a widely used adsorption material in engineering due to its abundant pore structure and larger surface area,and is competent for effectively adsorbing low concentrations of ethyl acetate.However,its adsorption capacity is limited,and a significant amount of activated carbon is required for replacing saturated activated carbon.Thus,proper treatment of saturated activated carbon is necessary to prevent it from becoming a secondary pollutant and hazardous waste.Further,activated carbon regeneration is a highly effective treatment method and deserves to be exploited for the engineering application of ethyl acetate control.This thesis focuses on the design and preparation of a novel composite adsorption material,the activated carbon/expanded graphite（AC/EG）composite,which has potential applications in the removal of ethyl acetate.The microwave irradiation recycling performance of the composite material was evaluated.The research revealed that the addition of expanded graphite improved the wave-absorbing performance of the composite material.The superb characteristics of microwave heat production and thermal conductivity of the expanded graphite contribute to achieving rapid heat transfer.After repeated adsorption and regeneration,the spent composite was used to capture methyl orange dye from the aqueous solution.The core conclusions of the study are as follows:（1）AC/EG composite adsorption material was prepared via the high-temperature wet pellet formation process with Al（OH）₃powder,dilute aqueous phosphoric acid（phosphoric acid:water（V/V）=3:7）,chitosan,AC and EG powder as reaction materials.The optimum preparation conditions are as follows:AC:EG:Al（OH）₃/phosphate solution:chitosan（m/m）=1.5:1:2:2.（2）The composite adsorption material was characterized for morphology,surface area,pore size,and distribution by SEM,BET,and FTIR.The results indicated that the activated carbon and expanded graphite powders were uniformly distributed in the composites.The surface area of the material was found to be 829.4486 m²/g,the pore volume was 0.438 cm³/g,and the average pore diameter was 2.1126 nm.After 7 cycles of usage,the surface area of fabricated material decreased to 230.4358 m²/g,the pore volume decreased to 0.127 cm³/g,and the average pore diameter increased to 14.1270 nm.The results of FTIR and Boehm titration demonstrated the presence of a significant number of carboxyl-,lactone-,and phenol hydroxyl acidic functional groups.（3）The effects of different parameters such as the initial concentration of ethyl acetate,gas intake,adsorption bed temperature,and adsorption bed height on the adsorption efficiency of the AC/EG composite were investigated.The adsorption process followed the pseudo-second-order kinetic equation,and mainly occurred in the pore.Compared with commercial activated carbon and expanded graphite,AC/EG composite material exhibits an excellent adsorption performance,lower carbon loss,and better mechanical strength.（4）The waste AC/EG composite was used to conduct the adsorption of methyl orange dye from the solution.Under optimal experimental conditions,the adsorption capacity of methyl orange is 304 mg/g,and the adsorption process of methyl orange is affected by the pore structure and pore size of AC/EG composite.This dissertation realizes the high efficiency regeneration of AC/EG composite adsorption materials by microwave irradiation,which lays a technical foundation for their application in the adsorption and disposal engineering of volatile organic compounds.