Adsorption Characteristics of Dissolved Organic Nitrogen on Aquifer Porous Media: The Role of Media Particle Size

Abstract

The adsorption of dissolved organic nitrogen (DON) bears the potential to exert a profound influence on the migration ability and groundwater quality. However, the effects of aquifer porous media, characterized by diverse particle dimensions, on the capacity of DON adsorption remain uncertain. The present study clarifies the characteristics and intricate machinations of DON adsorption on porous media with different particle sizes. Our findings suggest that DON adsorption has the potential to achieve immediate equilibrium, and the rate of kinetic adsorption increases as the particle size decreases. Fine sand exhibits a higher adsorption rate (0.030−0.058 kg (mg h) −1 ) and a greater adsorption capacity (137.73−486.67 mg N kg −1 ). Besides, adsorption capacities of amino acids and proteins on porous media are higher, caused by the forces of hydrogen bonding and ester groups. Urea's adsorption capacity exhibits the lowest values, and the main adsorption mechanism is the reactivity of carbonyl groups with porous media. The impact of environmental factors (DOM, metal oxides, and salinity) on adsorption pattern is mainly linked to DON types while being slightly affected by variations in the particle size of porous media. The study highlights that the capacity of DON adsorption on porous media is substantial enough to warrant consideration in site characterization and design of remediation strategies.