Study On Adsorption Of Ammonia Nitrogen By Hydroxyl-Aluminum Pillared Bentonite

In this paper, bentonite was pillared by hydroxyl polymeric aluminum which was formed by aluminum chloride and sodium carbonate. And the Al-pillared bentonite was calcined at500℃. The paper mainly studied the removal, influencing factors and adsorption mechanism of calcined Al-pillared bentonite on ammonia nitrogen wastewater processing and its application in practical wastewater to provide a scientific basis for application of Al-pillared bentonite in wastewater. The main results of this thesis were as follows:(1) Under certain experimental conditions, the molar ratio of OH/Al, preparing temperature of pillaring agent and washing had significant impact on adsorption performance of hydroxy-aluminum pillared bentonite on ammonia nitrogen wastewater. The optimal preparation conditions of pillaring agent was:the temperature of80℃, n (OH/Ai)=2.0. It could be seen that adsorption performance of Al-pillared bentonite was greatly improved after washed and calcined.(2) The simulated wastewater with ammonia nitrogen of100mg/L was treated with hydroxy-aluminum pillared bentonite and the influence of dosage, temperature, time, pH and initial concentration of ammonia nitrogen were discussed. The results showed that the removal of ammonia nitrogen could be up to96.6%when the dosage was120g/L, pH=9, the temperature was40℃.(3) The equilibrium data could be well interpreted by Lungmuir isotherm equation. The adsorption process of Al-pillared bentonite was fitted well with the pseudo-second rate equation and the adsorption process was mainly physical adsorption. The thermodynamic data showed that:the adsorption of ammonia nitrogen by Al-pillared bentonite was an endothermic reaction that the raising temperature was conducive to the adsorption reaction and it could happen spontaneously.(4) The ammonia nitrogen of315mg/L in practical wastewater could also be treated well with hydroxy-aluminum pillared bentonite. On the basisi of many factors affecting the adsorption of ammonia nitrogen,mainly have following conclusion that the removal of ammonia nitrogen could be up to61.9%when the dosage of4g, adsorption temperature of40℃, the adsorption time of2hours, pH=9. Therefore, the hydroxy-aluminum pillared bentonite could be used in practical wastewater treatment.