Regulation Of Crystal Growth Process And The K+ Adsorption Capacity Of Analcime

Coal fly ash?CFA?,an industrial solid waste,is produced by coal-fired power plants.With the increased demand of electric power,the emission of coal fly ash increased year by year.The large amounts of fly ash occupied land,which not only caused air and water pollution,but also threatened human health.CFA contains Si O₂ and Al₂O₃ components,which provides a possibility for the preparation of porous aluminosilicate materials.In this paper,sodium silicate and aluminum hydroxide extracted from fly ash were used as raw materials to synthesize analcime via hydrothermal synthesis.The technological parameters of zeolite synthesis system?starting material concentration,silicon aluminum ratio,crystallization temperature and crystallization time?were optimized.The regulation mechanism of anionic,cationic and non-ionic organic steric hindrance agents on the growth process of analcime was investigated,the crystallization kinetics of the zeolite was also performed.The zeolite products were characterized by XRD,SEM,FT-IR,BET and PSD.The regulation of steric hindrance agents on the pore structure of analcime during the crystal growth in the presence of nano-fiber doping were investigated,and the ion adsorption kinetics&thermodynamics were analyzed.?1?Taking sodium silicate and aluminum hydroxide as raw materials,the conditions for synthesizing analcime samples with high purity were as follows:the ratio of n?SiO₂?/n?Al₂O₃?is 8,the reaction temperature is 210,and the reaction time is 12 h.?2?The organic steric hindrance agents favored the smaller grain size and the larger specific surface area of analcime,then the yield of product was improved.With the addition0.5wt%SDBS,the crystallinity of products increased and the particle size distribution was more uniform,the average particle size of analcime was 2?m.At 25?,the K⁺maximum adsorption rate by analcime reached 87.36%as the adsorption time was 20 min.?3?The crystal growth curve of analcime presented "S" type of growths under the given conditions.Within a certain range,nucleation rate was positively correlated with temperature,and nucleation rate was not linearly related to the initial concentration of precursor.The higher the temperature,the faster the nucleation.When adding anionic steric hindrance agent SDBS to the reaction system,the crystal growth rate reached the maximum value.?4?By adding steric hindrance agents,the dispersion of carbon nano-fiber was improved.The pore volume and the specific surface area increased with the addition of carbon nano-fiber.The influence of steric hindrance agents on the pore structure of analcime was:CTMAB+ANA_CNF>SDBS+ANA_CNF>PVP+ANA_CNF.?5?The K⁺adsorption capacity of the analcime was:group CTMAB+ANA_CNF>SDBS+ANA_CNF>PVP+ANA_CNF.The adsorption kinetics of analcime were described by kinetic equation,R2>0.99.According to Langmuir isothermal adsorption equation,the maximum adsorption capacity of analcime with the addition of CTMAB was 78.686mg/g.According to Freundlich isothermal adsorption equation,it was found that when CTMAB zeolite was added,R2>0.99,1/n>1,the maximum of constant K_F was 528.68.