Dissolved organic nitrogen (DON) adsorption by using Al-pillared bentonite Original Research Article

Dissolved organic nitrogen (DON) is now considered as one of the most important issues in drinking water field. In this study, DON removal by using Al-pillared bentonite adsorption is studied. Adsorption kinetics, equilibrium isotherms and the effect of pH are investigated. The method based on pillared bentonite adsorption is proved to be effective in removing DON and related substances. The maximum adsorption capacities of the bentonites vary from 7.11 to 7.61 mg/g. Kinetic studies show that the adsorption of DON on the bentonites can be described by the pseudo-second-order kinetic model, and the intra-particle diffusion controls the limiting rate. pH is found to be the key parameter affecting DON removal. Acidic conditions are favored while alkaline conditions are impeded. Furthermore, it is found that the adsorption capacity of the pillared bentonites depends on the ratio of OH−/Al3+ during the pillaring process. Three-dimensional excitation–emission matrix (EEM) is also applied to assess the effect of adsorption on the removal of different DON fractions, and the results show that the tyrosine-like fractions are easier to be adsorbed.