LAUSR

In the current study, sorption isotherms, and kinetic and thermodynamic experiments were carried out to assess copper behavior in four soils from a toposequence located in the Brazilian Tropical Savanna (Cerrado). Adsorption data were investigated using non-linear regressions based on the models of Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich. Results were better described by Freundlich model, where the constant KF, related to the maximum copper adsorption capacity, varied from 0.68 ± 0.04 to 0.13 ± 0.02 mg/g and was mainly influenced by organic matter and 2:1 clays, where less weathered soils present higher concentration of stable adsorption sites. Kinetic parameters revealed that chemisorption was the rate-limiting step, while thermodynamic experiments show that the copper adsorption was spontaneous, endothermic and occurs with increase in system disorder due to desolvation. In the toposequence, results evidenced higher probability of environment contamination in the ferralsols, since copper exhibits weaker interaction with soil binding sites, mostly iron and aluminum sesquioxides.