Adsorption Characteristics of Ammonia-Nitrogen onto Different Lithology

Aimed at the current situation of nitrogen pollution in groundwater, adsorption characteristics of ammonia-nitrogen onto different lithology named silty sand, silty clay and clay were studied. The results indicated that the process of ammonia-nitrogen adsorption onto soils mainly occurred within 0~2 h, then attended to a dynamic equilibrium. Two kinetic models can describe the experiment data and adsorption onto different lithology obeyed the pseudo second-order kinetic model. The data of the ammonia-nitrogen sorption isotherms at different initial concentration ranges can be fitted by the linear form of Langmuir model remarkably. The maximal adsorption capacity of ammonia-nitrogen ranged from 0.088 to 0.540mg·g^-1. The retardant capacity of three lithology to prevent pollution are different and the clay is the best one.