Using ZnO-Al2O3 ceramic nanofibers and graphene oxide to simultaneously detect catechol and hydroquinone

Catechol and hydroquinone are two isomers of phenolics, which are widely used in various industries such as textiles, paints, plastics, oil refineries, cosmetics, pesticides, pharmaceuticals [1]. They are highly toxic to human health [2] and have been considered as well as environmental pollutants even at very low concentrations by Environmental Protection Agency and the European Union [3]. A novel voltammetric sensor based on ZnO-Al2O3 ceramic nanofibers and gold nanoparticles was used for simultaneous determination of catechol and hydroquinone. Ceramic nanofibers were electrodeposited onto the mixture of graphene oxide and chitosan simultaneously with gold nanoparticle electrode-position (scheme 1). The morphology and the structure of ceramic nanofibers were characterized by Field Emission Scanning Electron Microscopy, and Fourier transform infrared spectroscopy; these techniques confirmed the presence of ZnO-Al2O3 ceramic nanofibers on the electrode surface. The porous structures can be used for the simultaneous detection of isomers due to their satisfied results in concurrent analytes determination; then the porosity of ZnO-Al2O3 ceramic nanofibers was determined using Brunauer–Emmett–Teller (BET) test. The sensor has been applied for simultaneous determination of catechol and hydroquinone which indicated good results. The limit of detection and linear ranges are obtained 3.1 and 0.5 to 40 μM for catechol respectively. For hydroquinone, there are two linear ranges, 0.13 to 1 μM and 1.5 to 56.6 μM, and two limits of detection, 0.19 and 15.0 μM respectively. For catechol, the amounts of α and ks were 0.43 and 1.12 1/s, respectively and for catechol, they were 0.35 and 0.41 1/s, respectively. The sensor storage stability was investigated and the results showed that the electrode lost about 6.9% and 8.7% for catechol and hydroquinone of its first response after 1 week, respectively