In-situ optoelectronic kinetics mapping of green electrochemical graphene oxide production for advanced wastewater purification and circular plant cultivation

The study describes a novel, sustainable, and cost-effective process for producing graphene oxide using electrochemical exfoliation with a photovoltaic cell. This technology aims to reduce the harmful effects associated with the textile industry by using graphene oxide to treat industrial wastewater. The extraction of graphene oxide and nanosheets was achieved by intercalating a 1 M H2SO4 solution into the graphitic layer at a DC voltage bias of 2 V for 5 min, then increasing the voltage to 6 V DC for 6 h. The electrochemical exfoliation kinetics were verified mathematically using an integrated in situ photometric sensor circuit, which yielded an exponential voltage decay constant of 0.00853 min-1, confirming rapid, continuous colloid functionalization over the 6-hour runtime. Graphene oxide is identified via ultraviolet-visible spectroscopy (UV–VIS), Fourier transform infrared spectroscopy (FTIR), Dielectric Measurement, Scanning Electron Microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The direct electronic band gap of graphene oxide is calculated using Tauc's equation to be around 2.80 eV. The π to π* transition causes the absorbance peak in graphene oxide and nanosheets to appear at 260 nm. Graphene oxide shows a diffraction peak at 13.23 ˚ , and graphene nanosheet shows a diffraction peak at 26.61 ˚ . The dielectric constant of graphene oxide can reach values as high as 10 4 at low frequencies. Elemental analysis confirmed the successful preparation of graphene oxide, revealing precise carbon-to-oxygen (C/O) ratios of 2.95 and 2.85. The prepared graphene oxide demonstrated dye removal efficiencies of 98.28% and 97.55% for Methylene Blue and Indigo, respectively. Mung bean seedlings germinate with 100% success when purified water is used.