resumo
The aim of this work was to examine the effect of Cu(II) on the degradation of thiram (Thi) in aqueous solutions, since the literature focused on this effect is scarce and copper based fungicides can be applied together with thiram or during the same season to agricultural crops. The effect of Cu(II) on the degradation of thiram was followed by both UV-vis and HPLC-MS/MS. When thiram is dissolved in pure water its degradation occurs very slowly, being negligible during the first 7 days. However, the presence of Cu(II) has a strong influence on the thiram degradation in aqueous solutions along time. In the presence of an excess of Cu(II), a [CuThi](2+) complex is initially formed which degrades into a complex formed between the dimethyldithiocarbamate anion (DMDTC) and Cu(II) ion, [Cu(DMDTC)](+). This complex further degrades leading to other copper complexes which were identified for the first time, by MSn. The results obtained in the present work also demonstrated that a redox reaction involving DMDTC anions and Cu(II) ions gives rise to the formation of a Thi-Cu(I) complex. Finally, some of the complexes resulting from the degradation of [CuThi](2+) are quite persistent in solution for long periods of time (>1 month). (C) 2014 Elsevier B.V. All rights reserved.
palavras-chave
ISOCYANIDE COMPLEXES; CU(II) COMPLEXES; PESTICIDES; SOILS; WATER; ADSORPTION; CYPERMETHRIN; CYHALOTHRIN; LIGANDS; PLANTS
categoria
Engineering; Environmental Sciences & Ecology
autores
Filipe, OMS; Santos, SAO; Domingues, MRM; Vidal, MM; Silvestre, AJD; Santos, EBH
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Sónia Andreia Oliveira Santos
Investigador Auxiliaragradecimentos
O. Filipe wishes to acknowledge the PhD grant (SFRH/BD/39551/2007) from the Portuguese Science and Technology Foundation (FCT). S. A. O. Santos wishes to thank FCT and POPH/FSE for the postdoctoral grant (SFRH/BPD/84226/2012).; This work was supported by European Funds through COMPETE and by National Funds through the FCT within project PEst-C/MAR/LA0017/2013.; The authors also thank the financial support provided to CERNAS (PEst-OE/AGR/UI0681/2014), CICECO (PEst-C/CTM/LA0011/2013) and QOPNA (PEst-C/QUI/UI0062/2013) by the FCT.