Characterization of phosphorus interaction with sediments affected by acid mine drainage - relation with the sediment composition

Phosphorus sorption capacity was investigated in surface sediments derived from an abandoned zinc-lead mine area located in northeastern Algeria. The forms and the distribution of phosphorus in the raw sediment were identified using the sequential chemical extractions method. Batch experiments were done to study the adsorption kinetics and isotherms. The pH effect was evaluated by macroscopic and infrared analyses. In raw sediment, speciation results show that phosphorus is dominantly bound to oxyhydroxides. Sorption experiments demonstrate that phosphorus uptake is principally related to sediment composition. The nature of the dominant iron oxyhydroxide has a substantial role in the adsorption capacity and the mechanism interaction. The adsorption kinetics can be described by the second order and Elovich models. The isotherms data are successfully modeled by the Temkin equation. The maximum phosphorus removal is reached under acidic pH. Spectroscopic analyses reveal that the predominance of jarosite implies electrostatic interaction with sediment particles. However, in the case of schwertmannite predominance, phosphate ions are adsorbed by the ligand exchange mechanism.