Experimental Studies On Adsorption Of 13X Zeolite For NH₄～+-N Aqueous Solution

With the rapid development of the economy, the pollution of water source is increasingly serious. Ammonia-nitrogen(NH4+-N) is an important contaminant for cutrophication of water bodies and environmental pollution. With high concentration of NH4+-N, natural nitration is restrained, water becomes anoxic, fishes are poisoned, the self-depuration ability of water is reduced, and people's health are threatened. Therefore, our country and many other countries of the world established strict limitation of ammonia-nitrogen in wastewater emission criterion and drinking water criterion.13X zeolite is a kind of framework Silicate, has pore structure and large specific surface area, so it has unique adsorption and ion-exchange ability. It has good applicability in drinking water treatment. But, we have little knowledge about the process of ion-exchange when it is used to remove NH4+-N in wastewater, especially dynamic data.We have researched the adsorption properties for the removal of NH4+-N in low concentrations drinking water by using 13X zeolite from both static and dynamic, including primary influential factors, capacities of adsorption, desorption and mechanism.Through the static research, the conclusion can be shown that: the optimum conditions for the removal of NH4+-N are: the pH of the solutions is 6.5– 7.5, the adsorption time is 20 minutes and the adsorption temperature is 20-30℃. The adsorption capacity can reach 14.86mg of NH4+-N per gram of zeolite. Saturated 13X zeolite can be regenerated with good results by direct calcinations and without noticeable loss of capacity. It is suggested that ion exchange is the major mechanism for the removal of NH4+-N in wastewater. The static process of 13X zeolite to the adsorption of NH4+-N is fitted to Langmuir adsorption isotherm model, and the linear correlation coefficient(R) is 0.9996.Through the dynamic research, the conclusion can be shown that: with theincreased use of zeolite, and the increased high-columns, and the decreased intake-rate of wastewater, the adsorption of 13X zeolite to NH4+ rise, 13X zeolite could handle volume of wastewater is increased also while adsorption reached saturation. Under experimental conditions, the most dynamic saturation adsorption capacity is 24.20mg of NH4+-N per gram of zeolite. The dynamic renewable experimental of 13X zeolite adsorpted NH4+ results shown that: within normal activation temperature before use (13X zeolite activation temperature of 550°C), with the regeneration temperature higher, the results of 13X zeolite activation renewable is better. The dynamic process is fitted to Thomas adsorption model, the linear correlation coefficient(R) in different conditions is above 0.9. The experimental results show that the 13X zeolite is suitable for the removal of NH4+-N in wastewater and with good prospects for industrial application.