Síntese de óxido de grafeno a partir de grafita reciclada de baterias de íons de lítio e aplicação em membranas para remoção de corantes

Abstract

In the current scenario, the high consumption of electronic devices has triggered an increase in the demand for lithium-ion batteries (LIBs). These batteries are composed of valuable metals and graphite, necessitating the establishment of recycling alternatives for these materials to prevent the accumulation of electronic waste in the environment. In this context, the objective of this work was to recycle graphite from LIBs, apply it as a raw material for the production of graphene oxide (GO), and investigate the use of this GO as a coating material in hollow fiber membranes for the removal of dyes from aqueous solutions. For comparison purposes, four commercial graphites were used as parameters for the recycled material. The recycled graphite was characterized using X-ray diffraction (XRD), Raman spectroscopy, X-ray fluorescence (XRF), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and particle size analysis. The results showed that the extracted material exhibits characteristics similar to commercial graphites. The GOs were characterized using XRD, Raman spectroscopy, Fourier-transform infrared spectroscopy (FT IR), UV-Vis spectroscopy, TGA, SEM, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The synthesized materials displayed all the characteristics of high-quality GO. The GO synthesized from LIBs' graphite was mixed with the cross-linking agent ethylenediamine (EDA) to produce membranes (OG/EDA-2)D4, (OG/EDA-4)D4, and (OG/EDA-4)D24. The hollow alumina fiber without GO (AL) and the coated membranes were characterized through SEM, AFM, and hydraulic permeance analyses. Regarding the removal tests of Congo red dye, the membranes AL, (OG/EDA-2)D4, (OG/EDA-4)D4, and (OG/EDA-4)D24 showed retention rates of 21.53 ± 4.51%, 69.23 ± 1.05%, 99.68 ± 1.03%, and 98.35 ± 2.57%, respectively. The membrane (OG/EDA-4)D4 was also evaluated for the removal of crystal violet and remazol blue dyes, with removal percentages of 98.80 ± 0.04% and 90.89 ± 2.02%, respectively. Furthermore, the membrane (OG/EDA-4)D4 demonstrated the ability to be reused in multiple cycles and exhibited high stability in acidic and alkaline solutions, validating its use in industrial applications.