Preparation And Catalytic Performance Of Fly Ash Cenosphere-Based ABW Zeolite

Fly ash is an industrial waste residue produced by coal burning in thermal power plants and it is one of the largest industrial solid wastes in China.At present,thermal power generation is still the main source of electricity in China.There are too much fly ash stockpiling which often occupy much land causing serious environmental pollution,ecological damage,and huge waste of resources.Therefore,it is imperative for us to realize high value-added utilization of fly ash solid waste and to promote the development of circular economy of thermoelectric enterprises.Fly ash cenospheres are hollow microspheres with high content of activated silica and alumina extracted from fly ash,and they are ideal precursors for the synthesis of zeolite molecular sieves.In this paper,fly ash cenosphere?FAC?was used as raw material,the solution of LiOH?H₂O is employed as hydrothermal mother liquor to prepare fly ash cenosphere-based ABW zeolite?ABW?by hydrothermal reaction.The Co₃O₄ loaded fly ash cenosphere-based ABW zeolite?Co₃O₄/ABW?catalyst was synthesized by loading nano-Co₃O₄ semiconductor on the support of ABW by initial wet impregnation.The catalyst was characterized by XRD,FESEM,N₂ adsorption and desorption isotherms and XPS.At the same time,the experimental conditions for its catalytic degradation of direct fast bordeaux dye is optimized by orthogonal experimental design?OED?method.The result of XRD,FESEM and FT-IR characterization of the phase composition and micro-morphology of hydrothermal products showed that the pure phase ABW zeolite was successfully prepared by hydrothermal reaction taking fly ash cenospheres as raw material and LiOH?H₂O solution as hydrothermal mother liquor.A series of Co₃O₄/ABW zeolite catalysts with different contents of Co₃O₄ were synthesized by initial wet impregnation of Co?NO₃?₂·6H₂O on the carrier of NH₄⁺-ABW.XRD results showed that the Co₃O₄ dispersed on the surface of carrier in amorphous state when the loading capacity of Co₃O₄ was about 6 wt%,while there was Co₃O₄nanocrystal in the catalyst sample when the loading of Co₃O₄ increased to 12 wt%.XPS results showed that bivalent cobalt binding energy of the 2p_3/2 at 780 eV and 796 eV,and the trivalent cobalt binding energy of the 2p_1/2 at 785.9 eV and 802 eV.The orthogonal experimental design method was adopted to evaluate the effects of catalyst dosage,the loading of Co₃O₄,dye concentration,and solution pH on the degradation efficiency of direct acid-resistant bordeaux dye.The result of range analysis,variance analysis and factor index analysis showed that the main factors affecting the degradation of direct acid-resistant bordeaux dyes over Co₃O₄/ABW zeolite catalyst:the solution pH>the loading Co₃O₄>catalyst dosage>dye concentration.The optimal conditions for the degradation of direct fast bordeaux dye by Co₃O₄/ABW zeolite catalyst were that the loading capacity of Co₃O₄ was 6 wt%,the dosage of catalyst was 0.05g,the dye concentration was 20 mg/L,the solution pH was 3.0,and the degradation rate of direct fast bordeaux dye was up to 89.87%at 30 min.