Effective Removal of Nile Blue Dye from Wastewater using Silver-Decorated Reduced Graphene Oxide

Nile blue (NB) dye is a highly toxic substance that when discharged into sewage presents a significant risk to the environment and human health. Carbon-based nanomaterials, such as graphene oxide (GO), reduced graphene oxide (rGO), and their nanocomposites, offer considerable potential for eliminating hazardous pollutants from aqueous systems. In this study, we have successfully fabricated bare GO and rGO, and then, the rGO was decorated with silver (Ag) nanoparticles to develop the Ag-rGO composite. The as-prepared materials were characterized by various techniques, such as UV-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies, X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and scanning electron microscopy (SEM) to elucidate their structure, morphology, and chemical composition. The pollutant removal performance of the as-prepared materials was evaluated through a batch approach under the effect of various experimental variables for removal of NB dye from wastewater. As obvious, the Ag-rGO composite revealed exceptional performance for NB dye removal from wastewater, with a maximum removal percentage of 94% within 60 min, which is remarkably higher than those of the rGO (i.e., 59%) and GO (i.e., 22%), under the same experimental conditions. The adsorption data was analyzed with thermodynamics, isotherms, and kinetics models to better understand the physicochemical mechanisms driving the effective removal of the NB dye. The results reveal that Ag-rGO nanocomposite exhibit excellent adsorption ability as well as favorable thermodynamic and kinetic parameters for NB dye removal. It was also found that the presence of light enhanced the adsorptive removal of NB while using Ag-rGO as an adsorbent. The present study noted significant reusability of the Ag-rGO nanocomposite, likely due to minimal Ag leaching and/or the robust stability of the Ag-rGO. It is suggested that Ag-rGO-based hybrid materials could serve as promising candidates for efficiently adsorbing and catalytically removing various toxic pollutants from wastewater.