Amostras de ácidos húmicos de origem comercial (Fluka AG) foram usadas na avaliação do comportamento de adsorção de íons Cu2+. O modelo matemático descrito pela equação de adsorção de Langmuir em sua forma linear foi aplicado, obtendo-se os valores da capacidade máxima de adsorção b e da constante relacionada à energia de ligação a. Alíquotas de soluções de nitrato de cobre contendo várias concentrações desse metal foram adicionadas às amostras de suspensões de ácidos húmicos a pH constante. As isotermas apresentaram duas regiões distintas de adsorção, tanto a pH 4 como a pH 5, mostrando que o fenômeno adsortivo ocorre em duas etapas distintas, de acordo com o tipo de interação entre os ácidos húmicos e o cobre. As amostras de ácidos húmicos mostraram maior capacidade máxima de adsorção ao pH 5 do que ao pH 4, enquanto que a constante relacionada à energia de ligação foi maior em pH 4.

Commercial samples of humic acids (Fluka AG) were used to evaluate the adsorption behaviour of Cu2+ ions. The mathematical model described by Langmuir's adsorption equation was applied and the values of the maximum adsorption capacity b and those of the constant related to the bonding energy a were obtained. Aliquots of copper nitrate solutions with different copper concentrations were added to the humic acid suspensions at constant pH values (4.0 and 5.0). The Langmuir isotherms presented two distinct adsorption regions, showing that the adsorptive phenomenon occurs in two distinct steps according to the copper-humic site interaction. Samples of humic acids showed higher maximum adsorption capacity at pH 5 than at pH 4, while the constant a related to bonding energy was higher at pH 4.

The chemical and physical characterization of coastal peat has been studied. It was examined the pH, organic matter content and elementary and XRD analyses, among other characteristics. The peat was then applied to the retention and competition of metal micronutrients (Cu and Zn) from metal nitrate solutions. The retention was affected by both the pH and time of adsorption, while the competitive character of these metals for the substrate was relevant to each pH examined.