Individual and Competitive Adsorption of Copper, Zinc and Lead in Soils with Contrasting Texture

Abstract

Waste is often disposed of in the soil, leading to contamination not only by a metal, but by two or more elements. The adsorption studies are a way of evaluating the behaviour of the different metals when in contact with the soils. This study aimed to evaluate the effect of adsorption of Cu, Zn and Pb, in an individual and competitive system, in soils with contrasting texture. To achieve the goals, two types of soils, typical of the state of Paraná (PR), Brazil were used. One of the samples (Soil A) were collected in the city of Francisco Beltrão, classified as a typical dystrophic Red Latosol (Oxisol) and the other (Soil B) were collected in the city of São Pedro do Paraná in the region of Paranavaí, classified as a Red-Yellow Argisol Abruptic eutrophic. The soils were characterised by chemical, granulometric, and mineralogical analyses. The metals adsorption were tested by the batch method. With these results, adsorption parameters derived from the Langmuir and Freündlich models were obtained. The adequacy of the Langmuir and Freündlich equations to the adsorption results did not occur in all situations but was satisfactory. Pb presented the highest values of maximum adsorption capacity estimated by the Langmuir model. Simultaneous adsorption reduced the adsorption of the three metals, with the highest reductions observed for Zn. Zn’s lower competitive power, evidenced by the reduction of its adsorption capacity in the presence of other metals, makes this element very worrisome in more weathered tropical soils, since it indicates a greater predisposition of this element to the movement in the profile or in superficial waters.