Study On Preparation Of NaA And NaX Zeolite From Fly Ash And Adsorption Properties For Cd²⁺

Fly ash is a power plant in the process of coal formation,as a result of the demand for electricity,its production is increasing.With the development of economy and industry,the discharge of wastewater containing heavy metals such as cadmium also poses a great threat to human health.The preparation of zeolite with fly ash as raw material and the treatment of heavy metal wastewater is an effective way of turning fly ash into treasure,high value,high resource and environmental benefit.In this paper,NaA and NaX zeolite were prepared by alkali melting and hydrothermal method using waste fly ash from a power plant in Huainan as raw material.The influence factors of preparation experiment were studied,and the process parameters were optimized.The products were characterized by XRD,SEM,FTIR,TG-DSC and so on.In addition,the adsorption properties of two kinds of zeolite on Cd²⁺ were also studied and analyzed.The main results of this paper are as follows:?1?Fly ash pretreatment:The fly ash was mechanically milled by 30min,which can make the surface of the powder activated,destroy the structure of the glass,increase the specific surface area,increase the surface active sites and enhance the reactivity.The removal of impurities by HCl acid can reduce the influence of metal ions on the preparation process and improve the quality of the products.?2?Preparation of NaA and NaX zeolite:The optimum process parameters were obtained:NaA zeolite:Ash alkali ratio was 1:1.5,The calcination temperature was 750? The crystallization temperature was 90? The crystallization temperature was 8h.NaX zeolite:Ash alkali ratio was 1:1,The calcination temperature was 850?,The crystallization temperature was 90?,The crystallization temperature was 12h.?3?Characterization of NaA and NaX zeolite:The results showed that two kinds of zeolite were successfully prepared by XRD spectrum analysis.The appearance of NaA and NaX zeolite observed by SEM is cubic and positive eight,the particle size is even,the outline is clear.The characteristic skeleton structure of NaA and NaX zeolite was judged by FTIR spectrum analysis method according to the position of the peak.The thermal stability of the two products prepared by TG-DSC curve analysis is very good.?4?Adsorption of Cd²⁺ on NaA and NaX zeolite:Several factors affecting the adsorption process were investigated,The experimental results show that the adsorption time,the amount of zeolite,the initial concentration and the initial temperature have some influence on the adsorption results.The results of adsorption were analyzed by adsorption kinetics and adsorption isotherm,the results showed that the adsorption process of Cd²⁺ for two kinds of products was in accordance with the Lagergren quasi two order kinetic model,and the adsorption isotherms were consistent with the Langmuir model.