SENSOR ELETROQUÍMICO A BASE DE NANOMATERIAIS PARA DETERMINAÇÃO DE POLUENTES ORGÂNICOS (BENZENO, TOLUENO, XILENO E NAFTALENO) EM ÁGUAS DE POSTOS DE COMBUSTÍVEIS

Abstract

In this study, electrochemical sensors were developed to determine benzene, toluene, xylene (BTX) and naphthalene (Naf) in water samples from gas stations using a glassy carbon electrode (ECV) modified with nanomaterials. Among the sensors, AuNP/RGO-GCE was prepared by electrodeposition of gold nanoparticle (AuNP) film adsorbed on reduced graphene oxide (RGO) on the ECV surface. The MnxOy/MWCNT-GCE was obtained by depositing 10 L of the suspension of the nanocomposite of manganese oxides (MnxOy) and multi-walled carbon nanotubes functionalized with -COOH (MWCNT) on the ECV. The AuNP/RGO-ECV sensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) techniques. In contrast, MnxOy/MWCNT-GCE was characterized by CV, SEM, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and transform infrared spectroscopy techniques. Fourier (FTIR). The quantification of organic compounds (BTX and Naf) was carried out using the differential pulse voltammetry (VPD) technique, with previously optimized parameters. The AuNP/RGO-GCE sensor, used to determine BTX, showed a linear response in the range of 30 - 240 μM, with limit of detection (LOD) in the range 1.8 - 2.2 μM, 2.2 - 2.7 μM, 2.0 - 2.6 μM and limit of quantification (LOQ) of 6.2 - 7.3 μM, 7.2 - 8.9 μM, 6.6 - 8.8 μM, respectively for benzene, toluene and xylene. In addition to satisfactory repeatability (DPR 1.5 – 2.6%) and stability (90.8 - 92.2%) in the determination of BTX. The method showed good selectivity in the presence of molecules with similar chemical structure, presented good accuracy with recovery ranging from 97.8% to 103.1%. For Naf, the MnxOy/MWCNT-GCE sensor was used with a linear range of 2.0 μM - 16.0 μM, LOD of 0.5 μM and LOQ of 1.8 μM. With satisfactory repeatability (DPR of 7.8%) and stability (900 s). The recovery tests obtained were 98.1% to 103.3%. The results obtained suggest that the AuNP/RGO-ECV and MnxOy/MWCNT-GCE sensors have great potential for application in the detection of BTX and Naf, in water samples from the gas station separator box and well, respectively.