Study On Adsorption Of Heulandite To Ammonia Wastewater

In recent years,with the rapid development of social economy,plenty of industrial waste and the sanitary sewage with high density of ammonia nitrogen pour into water bodies,which caused the drop of water source's quality,eutrophication of water body and serious environmental pollution.Ammonia-containing Wastewater with higher vanadium concentration limits the regular biological treatment process.Zeolite is the non-metal mineral resources well stocked in China,which is widely distributed and is cheap and easy to obtain.Zeolites own a number of superior physicochemical properties due to their special crystal structures and the chemical compositions.It can be widely used in nitrogen of wastewater.This paper used natural heulandite in Lingshou of Hebei province as adsorbent,and ammonia nitrogen wastewater as the research object.The adsorption properties of natural and modified heulandite on high ammonia nitrogen were studied by static and dynamic adsorption experiments.Optimize the modification and regeneration conditions of heulandite by the single factor and orthogonal experiments.Structures of the natural and modified and regenerated heulandite were characterized by SEM,BET,XRD and FTIR.At the same time,the ammonia nitrogen removal mechanism was analyzed by adsorption kinetic thermodynamics and adsorption isotherm.The results show that:1)The adsorption capacity was 8.5mg/g when the dosage was 5g,the pH was 5,the rotational speed was 200r/min and the reaction was 210min.The adsorption of NH₄⁺on natural heulandite was fitted to the quasi-two-order kinetic.Freundlich adsorption isotherm could describe the adsorption process.2)It was concluded that the removal efficiency of ammonia nitrogen by NaCl was the highest in the salt modification method through the single factor analysis.The sodium type heulandite could be prepared by the static reaction of 10h with NaCl concentration of1mol/L at the particle size of 300⁶00?m,at 40?.The adsorption capacity of sodium type heulandite to ammonia nitrogen was 17.39mg/g when the dosage was 2.5g,pH was6⁸,the reaction time was 180min,and the initial concentration of ammonia nitrogen was about 500mg/L.Compared with the natural heulandite,both of them fitted with the pseudo-second-order kinetics equation and the sodium type,and the adsorption of ammonia nitrogen by sodium type heulandite conforms to the Langmuir isotherms.The optimum retention time was 30 min in the dynamic adsorption experiments.3)NaOH regeneration solution was better for the treatment of saturated heulandite.The optimum preparation conditions of regenerated heulandite:reaction time was 3h,NaOH concentration was 0.1mol/L,solid-liquid ratio was 5:100.When the amount of regenerated heulandite was 5 g/100 ml,the average removal rate was 91%when reacted in neutral acid solution for 150 min.It was found that the removal rate and the adsorption amount of ammonia on the saturated heulandite were all restored by repeated regeneration test.The above results show that the natural heulandite has better effect on the treatment of ammonia nitrogen wastewater,and the original skeleton structure of heulandite can be maintained,and the dosage of heulandite can be reduced at the same removal rate.The regeneration of heulandite provides good data and theoretical basis for the recovery and utilization of heulandite.