SENSOR ELETROQUÍMICO A BASE DE Ni/SBA-15 PARA DETERMINAÇÃO DE COBRE EM ETANOL COMBUSTÍVEL

Abstract

This work presents the development of an electrochemical sensor, based on the modification of a graphite polyurethane composite electrode with 5% of Ni/SBA-15, applied to the determination of Cu2+ in ethanol fuel. In this study a comparison between the electrodes of graphite polyurethane was made, with and without the modifier SBA-15 composite. The study was carried out with the anodic stripping voltammetry technique in the square wave mode (ASV/SW) and the standard addition method. From the calibration curve, it was found that when Ni is incorporated in to silica nanomaterial, the slope is about two times higher than when metal that has not been incorporated into the nanocomposite. The electrochemical sensor containing Ni/SBA-15 was then evaluated electroanalytically for determination of Cu2+ in ethanol fuel samples, using the ASV/SW, and as a supporting electrolyte, the ammonium sulphate ((NH4)2(SO4)) 0,1 mol L-1 and pH = 3. After voltammetric study for optimization of experimental conditions and equipment, we obtained the following data, considered ideal: deposition potential (Edep) = -0,5 V; preconcentration time (tpré) = 160 s; frequency (Freq.) = 60 Hz, amplitude (amp) = 25mV and step potential ( step) = 5 mV. For statistical validation procedure, the accuracy of the method was determined through recovery tests, whose results were concordant, showing a recovery value in the concentration of Cu2+, 91%. The results obtained in the analyzed sample had an average value of 6,07 x 10-8 to Cu2+ concentration, showing that the graphite polyurethane composite electrode modified with Ni/SBA-15 is a great sensor for Cu2+.