Preparation of Zeolite Molecular Sieve with Fly-ash and Its Application in Adsorbing and Removing Ammonia Nitrogen
Presently,the emission of a large amount of nitrogen-containing wastewater into lakes not only aggravates lake eutrophication,but also poses severe threats to the health and survival of various species of organism.This article refers to a kind of zeolite molecular sieves that can be used to adsorb and remove ammonia nitrogen(NH3-N)from water due to the good adsorption selectivity and ion exchange.A laboratory experiment was performed with the fly-ash sampled collected from a thermo-power plant as main raw material to prepare Na-X zeolite by alkali melting-hydrothermal method,and the orthogonal experiment was conducted to determine the optimal preparation process condition.The experiment of NH3-N adsorption was thereby conducted probing into the effect of the initial NH3-N concentration,pH,adsorption time,adsorption temperature and cations on the adsorption of NH3-N by the zeolite.It was showed that the best saturated NH3-N adsorption rate of Na-X zeolite reached 74.89％,and the process of NH3-N adsorption onto Na-X zeolite fit the quasi-second-order kinetic model,and the adsorption isotherm conformed to the Freundlich model,NH3-N adsorption capacity being positively correlated with the initial NH3-N concentration and adsorption time,and negatively correlated with temperature.To sum up,the Na-X typed molecular sieve features rather high NH3-N adsorption rate,and could be recycled a number of times,so it has wide appli-cations in wastewater treatment.
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