Development of Modified Electrodes Based on Self Assembled Films of Polypirrole and Carbon Nanotubes Composites for Pest
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Development of Modified Electrodes Based on Self Assembled Films of Polypirrole and Carbon Nanotubes Composites for Pesticides Monitoring Gabriela Martins de Araújo1; Luis Antonio Polacci1; Tatiana Mazo1; Lúcia Codognoto2; Fábio Ruiz Simões1*. 1
Departamento de Ciências do Mar, Universidade Federal de São Paulo, Av. Almirante Saldanha da Gama, 89. CEP 11030-400, Santos – SP, Brazil 2 Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Rua Prof. Arthur Riedel, 275, CEP 09972-270, Diadema – SP, Brazil. Abstract In this work polypyrrole (PPy) and its respective composite with functionalized multiwalled carbon nanotubes (PPy-MWCNT) was obtained by the chemical polymerization of the monomer pyrrole (PPy) in aqueous solution by the dropwise addition of a solution of ammonium persulfate (PSA). The obtained PPy as well as its composite (PPy-MWCNT) were used to prepare two self-assembled films (SA) by the immersion of ITO blades (Inidium Tin Oxide) into PPy and PPy-MWCNT dispersions with alternated immersions into Polystyrene sulfonate (PSS) dispersion, thus resulting in a bilayer. The SA films were produced with ten bilayers (alternated layers of PPy or its composite). The obtained films were characterized by Fourrier Transformed Infrared Spectroscopy (FTIR), UV-Visible analysis, voltammetric analyses (square wave and cyclic voltammetry) and Scanning Electron Microscopy (SEM). The SA films were evaluated to determine the chlorothalonil pesticide which is commonly used as anti-fouling agent in marine environments. The SWV results showed a reduction peak at around -0.8 to 1.2 V (according to pH). It was also observed a synergic effect of the composite film (PPyMWCNT/PSS) to determine the chlorothalonil by increase of the peak currents. 1.
Introduction Pesticides have been widely used worldwide for decades, being the largest group of substances classified as endocrine disruptors. Several studies show the detection of pesticide residues in food, drinking water and water bodies. Specifically, in marine environment, in recent years, those pesticides emerge as biocides used as active ingredient in antifouling paint on commercial vessels and, oil rigs, underwater pipes, sluices, dams tanks intended for aquaculture, among other structures with the purpose to combat the formation and establishment of biofouling communities on surfaces exposed to water [1,2]. The Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) is an organochlorine pesticide, which has been used for more than 30 years as a fungicide in world agriculture. However, their use as active biocides in antifouling paints started after the banishment of paints based on organotin [1]. The analytical methods used for the determination of pesticides in environmental analyses are generally based on chromatographic techniques which generally use organic solvents and are time consuming. In this sense, new electrode materials which could be used to sensoring of these substances offer several advantages such as low cost, are fast, do not uses organic
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