Sorção de cobre e zinco em pó-de-metabasalto e em argilominerais de referência

Abstract

Ion sorption is a physicochemical phenomenon that retains and releases the chemical elements of the particles into the soil solution and involves agricultural and environmental aspects. In agricultural areas of Brazil and the world the application of copper fungicides and, animal waste rich in copper and zinc usually result in a process of environmental contamination. Knowing natural materials with sorption capacity becomes increasingly fundamental while they can be used as soil remediation or in the purification of contaminated water. The metabasalt contains highload clay and may have sorption capacity of copper (Cu2+) and zinc (Zn2+). The aim of the present work was to evaluate if the ground metabasalt presents Cu2+and Zn2+sorption capacity in magnitudes comparable to the reference clay minerals (kaolinite, montmorilloniteand,illite)and also to discuss the materials mineralogical behaviour in front of the sorption phenomenon. For this, the materials were submitted to adsorption with Cu2+and Zn2+ in a competitive system at the doses of 3000 and 6000 mg kg-1 in chloride form and subjected to sequential desorption with cation exchange resins. Materials mineralogy behaviour was evaluated by X-ray diffraction, before, after the adsorption and after the ions desorption. All materials adsorbed higher amounts of copper than zinc, highlighting the metabasalt. The metabasalt desorbed Cu2+ and Zn2+slower than the reference clay minerals. By presenting high load clay minerals with expandablecharacter (smectites and celadonites), metabasalt adsorbed Cu2+and Zn2+in the interlayer, which delayed the desorption of these ions in the desorption tests since it is an ion diffusion process. In this sense, metabasalt presents superior sorption capacity to the reference clay minerals suggesting that ground metabasalt has potential of use as a water decontamination agent and in another use, as slow release of these ions in agricultural soils.