Thiram and picloram as entrapping agents for lead depicted by electrochemical methods

Abstract

A afinidade de dois pesticidas muito utilizados com diversas especificidades, isto é, o fungicida Thiram e o herbicida Picloram, por íons chumbo foi estudado por medidas eletroquímicas. O perfil voltamétrico de redissolução anódica para o íon metálico estudado foi significativamente afetado pela natureza química dos pesticidas (ligantes) e uma nova interpretação foi feita sobre a natureza, força e possível estequiometria dos complexos formados. Thiram causou um pronunciado efeito no sinal de redissolução do Pb. Algoritmos de linearização dos dados de titulação permitiram calcular a constante de estabilidade condicional para o Thiram (log K'= 6,8) e Picloram (log K' = 6,0). Foi encontrado que ambos os pesticidas contribuíram para a formação dos respectivos complexos 1:1 com Pb em uma alta porcentagem (aproximadamente 83%). The affinity of two widely used pesticides of diverse specificities, i.e., the fungicide Thiram and the herbicide Picloram, for lead ions has been studied by an electrochemical approach. The anodic stripping voltammetric profile of the studied metallic ion was significantly affected by the chemical nature of pesticide (ligand) used and new light has been shed on the nature, strength and possible stoichiometry of formed complexes. Thiram caused a pronounced effect on the stripping signals of Pb. Linearization algorithms of titration data with the metal allowed the conditional stability constant to be calculated for Thiram (log K' = 6.8) and Picloram (log K' = 6.0). It was found that both pesticides contribute to the formation of the respective 1:1 complexes with Pb in a high percentage (ca. 83%).

Spectroscopic and electrochemical investigation of interactions between metal Cr(VI) and Thiram (Tetramethylthiuram disulfide)

“…Thiram has the potential to act as a ligand and to form complexes with metals (Valle et al, 2010). This ability has allowed the commercialization of a Zn enriched analogue of thiram which is known as Ziram (Borg and Tjaelve, 1988).…”

“…Figure 2: Schematic representation of (A) Ziram (Borg and Tjaelve, 1988); (B) The complex between Pb and Thiram (Valle et al, 2010); (C) S-S bond cleavage of Thiram (Valle et al, 2010;Sanchez-Cortes et al, 1998;Kang et al, 2002).…”

“…Since heavy metal ions such as Pb, Cr can be present in the environment as an impurity of agro chemicals, metal complexes will be naturally formed in most soils where pesticides have been applied (Valle et al, 2010). It has been known for many years that Cr(VI) is highly toxic and contributes to environmental pollution as well as plant toxicity vastly (Oliveira, 2012).…”

“…In the present study, the affinity of thiram for Cr(VI) ion has been studied by cyclic voltammetric and UV-Visible spectroscopic methods. With the help of such interactions, the degree of toxicity of both thiram and Cr(VI) towards the environment could be altered (Valle et al, 2010). Such interactions could probably lead to utilize thiram (Valle et al, 2010) as an entrapping agent for Cr(VI).…”

“…With the help of such interactions, the degree of toxicity of both thiram and Cr(VI) towards the environment could be altered (Valle et al, 2010). Such interactions could probably lead to utilize thiram (Valle et al, 2010) as an entrapping agent for Cr(VI). Therefore, investigating interactions between thiram and Cr(VI) could be important as a solution to the increasing environmental pollution.…”