Modeling rare earth elements binding to humic acids with model VII

Rare earth elements (REE) naturally occur at trace levels in natural systems but, due to their increasing use modern technologies, they are now released into the environment, and considered as emerging contaminants. Therefore, development of numerical predictive models speciation various physico-chemical conditions is required predict behavior, transport potentially toxic effects on ecosystems. Because REE largely affected by organic matter, such humic acids (HA), this study aimed calibrating an advanced humic-ion binding model (Model VII) allow predicting REE-HA pH conditions, ionic strength [REE]/[HA], well presence competitor ions. First, complexation monodentate O-containing ligands was evaluated using Irving-Rossotti equation, which provided constraints for optimization parameters Model VII. Predictive capacities VII were demonstrated successfully modeling cations (Al3+, Fe3+, Cu2+ Ca2+) carbonates binding. The large range applicable suggest that present might be used more accurately role played NOM very contrasting environments, groundwaters, rivers, estuaries, seawater, soils or sediments. provides a valuable tool fate environment.