SENSOR ELETROQUÍMICO À BASE DE NANOTUBOS DE CARBONO E NANOPARTÍCULAS DE ÓXIDO DE FERRO PARA DETERMINAÇÃO SIMULTÂNEA DE HIDROQUINONA E RESORCINOL EM ÁGUAS SUPERFICIAIS

Abstract

Hydroquinone (HQ, 1,4-dihydroxybenzene) and resorcinol (RS, 1,3-dihydroxybenzene) are benzene derivatives extensively used in agricultural activities, chemical and pharmaceutical industries. Furthermore, they are considered emerging microcontaminants due to their persistent toxicity to plants and animals, even at extremely low concentrations. This work proposes an electrochemical sensor based on a glassy carbon electrode modified with multiwalled carbon nanotubes functionalized with carboxyl groups and iron oxide nanoparticles (GCE/MWCNT-COOH/Fe2O3) for simultaneous determination of hydroquinone (HQ) and resorcinol (RS) in surface water samples. The physicochemical properties of the materials (Fe2O3, MWCNT-COOH and MWCNT-COOH/Fe2O3) were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The electrochemical properties of the sensor were evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The GCE/MWCNTCOOH/Fe2O3 sensor showed an increase in the voltammetric peak currents of HQ and RS compared to the unmodified GCE and the GCE modified with the individual materials (GCE/MWCNT-COOH and GCE/Fe2O3). Under optimized conditions, the proposed sensor showed an excellent performance for the simultaneous determination of the analytes, showing a linear behavior in the range of 10 to 150 μM for HQ and 15 to 150 μM for RS. The calculated limits of detection (LODs) for HQ and RS were 0.49 μM and 0.70 μM, respectively. Furthermore, good results in terms of precision, accuracy, and stability were observed. The proposed sensor was successfully applied for the determination of HQ and RS in river water, with satisfactory recovery values. The results indicate from an analytical and statistical point of view that the proposed sensor is suitable as an alternative method to perform the determination of HQ and RS in water samples.