Green Approach To Produce a Graphene Thin Film on a Conductive LCD Matrix for the Oxidative Transformation of Ciprofloxacin

This study demonstrates the use of disposed liquid crystal display (LCD) glass as a supporting matrix for the fabrication of a binder/linker free thin film graphene electrode. Graphene oxide (GO) was drop tasted onto the LCD matrix and electrochemically reduced to form an ErGO LCD electrode which was subsequently employed for the electro-Fenton oxidation of ciprofloxacin. Fourier transform infrared spectroscopy confirms the presence of (i) functional groups such as C=O, N H, C N, and C N on the LCD matrix, (ii) attachment of GO onto the LCD, and (iii) reduction of oxygen functionalities at the surface of the ErGO LCD electrode. Raman and X-ray photoelectron spectroscopy were performed to examine the nature and chemical composition of the GO-LCD and ErGO LCD electrodes. Cyclic voltammetry and electrochemical impedance spectroscopic studies revealed the enhancement of the oxidation reduction properties and reduction of charge transfer resistance (R-ct, 17 Omega) in the presence of [Fe(CN)(6)](3-4-) redox species. Electro-Fenton results revealed that a high concentration of H2O2 (45 mg L-1) was produced at acidic pH as compared to neutral (20 mg L-1) or alkaline (15 mg L-1) conditions. Furthermore, a higher current efficiency for the production of H2O2 was found at 1.0 V (63%) as compared to 1.5 V (59%) and 2.0 V (51%). Degradation studies showed >99% removal of ciprofloxacin was observed at pH 3.5 as compared to pH 7.0 (92%) or pH 9.0 (77%) at 1.5 V. The reuse experiments suggested that the electrode is stable and reusable for more than 7 cycles of experiments. The average pseudo-first-order kinetic rate constant for seven cycles of reuse was found to be 0.017 min(-1).