Voltammetric and spectroscopic studies of the interaction between copper (II) ions with the pesticide carbendazim and its effect in the soil

Abstract

The pesticide carbendazim (MBC) has nitrogen and oxygen in their structure which can interact with metal ions. This work evaluated the interaction between copper (II) ions with the pesticide carbendazim. The results obtained by cyclic voltammetry (CV) in 0.4 mol L-1 Britton-Robinson (BR) buffer (pH 4.0), under glass carbon electrode (GCE) to the MBC, showed an oxidation peak at 1.02 V and a reduction peak at 0.78 V vs Ag/AgCl, with characteristics of a quasi-reversible process controlled by the diffusion of the species in solution. For the Cu2+ metal ions, two reduction peaks were observed at -0.26 and -0.11 V and an oxidation peak at 0.04 V vs Ag/AgCl, with characteristics of a quasi-reversible process, controlled by the diffusion of the species in solution. In the interaction between carbendazim and copper metal ion, the formation of an oxidation peak around 0.60 V vs Ag/AgCl and a reduction peak around 0.08 V was observed, in a 1:1 ratio (Cu2+:MBC) in solution, suggesting that a new compound was formed. Complex formation was confirmed by UV-Vis spectroscopy, where changes were observed in the MBC absorption band and Cu2+ d-d band, suggesting the formation of a MBC-Cu complex. Analyses with the soil samples showed that after 30 min of the presence of the carbendazim solution in the soil, the pesticide had around 80% of its initial concentration adsorbed. When carbendazim is in the presence of the Cu2+ ion, about 62% of the pesticide is adsorbed, indicating that complexation influences adsorption of the species in the soil studied.