Simultaneous adsorption of amoxicillin and ciprofloxacin on agricultural soils and by-products used as bio-adsorbents: Unraveling the interactions in complex systems

The presence of pharmaceuticals in agricultural soils, like amoxicillin (AMX) and ciprofloxacin (CIP), poses a significant environmental challenge with potential implications for ecosystems and human well-being. This study explores the simultaneous adsorption of AMX and CIP on crop soils and bio-adsorbents, focusing on competitive adsorption dynamics. Tests were conducted with varying pharmaceutical concentrations in six soils and three bio-adsorbents. CIP consistently exhibited higher adsorption than AMX, particularly at higher concentrations. In the binary system, AMX's adsorption exceeded the individual system at higher concentrations, implying a synergistic effect. Bio-adsorbents, especially pine bark and oak ash, displayed superior adsorption capacities compared to soils. Some soils exhibited enhanced adsorption and retention of both antibiotics simultaneously, aligning with the cooperative adsorption model. Freundlich's adsorption model described the competitive adsorption systems well. These findings have implications for addressing antibiotic contamination in agricultural ecosystems, offering insights into complex interactions in soil environments amid rising pharmaceutical concerns.