Study on the adsorption of ammonia nitrogen with the best modified zeolite

Abstract In this paper, the natural zeolite is taken as the research object to treat the ammonia nitrogen water source, using acid, alkali and salt modification method to modify the natural zeolite, and found that the natural zeolite under NaCl modification has the best adsorption performance on ammonia nitrogen (removal rates up to 75.5% after adsorption stabilization). Then, the optimal adsorption effect of ammonia nitrogen was studied under different NaCl concentrations, zeolite particle sizes, modification time, and modification temperature. The results show that the concentration of optimal modified sodium chloride was 2 mol/L, the zeolite particle size was 80 mesh, the modification time was 6 h, and the modification temperature was 20 ℃. The adsorption dynamics of the modified zeolite by NaCl are preliminarily explored. The R 2 of the quasi-second-order model is close to 0.99, indicating that the adsorption process follows the quasi-second-order kinetic equation. In the study of adsorption thermodynamics, ΔH is less than 0, indicating that the process of zeolite adsorption of ammonia nitrogen is an exothermic reaction. This result is consistent with the conclusion of adsorption isotherm and further proves that low temperature is beneficial for ammonia nitrogen adsorption. This provides a reference base for adsorption studies of modified zeolites in nutrient salts such as ammonia nitrogen. Graphical Abstract