| About 50% of fly ash were mainly utilized in concrete production at home, the rest of them were utilized in many other areas, including soil improvement, ceramic industry, industrial catalysis, adsorption of various pollutants, zeolite synthesis and the recovery of precious metal. It could be seen that the utilization of fly ash way were very broad, though, most of them were low value-added, which perhaps could lead to a waste of resources of fly ash to some extent. Thus the utilization situation of fly ash was still very severe.In this paper, we used a silicon-aluminum component (Na2SiO3 and NaA102) obtained by stage treatment of fly ash as raw material, the NaP zeolite was prepared by hydrothermal synthesis. We studied effects of different kinds of anionic sodium salt and organic space steric hindrance on preparation of the NaP zeolite, the process parameters of hydrothermal synthesis system of the NaP zeolite was optimized, and the crystal type, morphology and pore volume of NaP zeolite were analysed and characterized by XRD, SEM and BET. Also, the adsorption capacity to Ni2+, Cu2+ and Fe3+ in aqueous solution of NaP zeolite was evaluated, and the zeolite was regenerated after saturation adsorption. The results are as follows:(1) The activation energy created by the reaction between Na2CO3 and fly ash undermined the original silicon aluminum lattice in fly ash, altered the keys in it, and increased the activity of fly ash. We studied several conditions in activation phase of fly ash, they are calcination temperature, calcination time and ratio of raw materials, through which we concluded that the optimal activation condition is:temperature 840℃, calcination time 3 h, ratio of raw materials (fly ash/soda ash) 1:1.5. The aluminum ion extraction rate in the fly ash can reach 80.89% after acid pickling in this optimal condition.(2) The appropriate preparation conditions of NaP zeolite with low SiO2/Al2O3 molar ratio using fly ash as raw material were as follows:crystallization temperature 120℃ crystallization time 8 h, n(H20)/n(SiO2)=116, n(Na20)/n(SiO2)=1.6. When the anion in sodium salt was Br, the productivity and purity of P zeolite are both largely increased. After adding TEA as organic space steric agent (n(TEA):n(Al2O3)=1:1), the particle size of synthesized P zeolite was smaller which can improve the pore volume of zeolite.(3)The adsorption performance had been tested on P zeolite, and concluded that the adsorption performance of P zeolite added triethanolamine is better than the othe two, metal ions’adsorbed capacity’s order was Cu2+>Ni2+>Fe3+. It could be found that the dynamic adsoption process of Cu2+on P zeolite conformed to Lagergren two-order kinetics model and Langmuir isothermal adsorption model.(4) Alter some regeneration researches on absorbed P zeolite using different experimental methods, the optimal conditions for regeneration of P zeolite using some additives were as follows:use EDTA-2Na as a renewable auxiliary with a concentration of 0.01 mol/L, regenerate for 30 min under 30℃, with a removal rate of 97.9%, however, a certain loss of the molecular sieve too. The optimal conditions of ultrasonic treatment on P zeolite were as follows:regeneration temperature 35℃, regeneration time 12 min, with the ultrasonic power ratio is 60%. Under the above condition, removal rate of the treated P type molecular sieve towards the copper ions in water could reach 97.4%. |
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