Graphene Oxide/Co3O4 Nanocomposite: Synthesis, Characterization, and Its Adsorption Capacity for the Removal of Organic Dye Pollutants from Water.

In this work, graphene oxide/Co3O4 nanocomposite was synthesized via hydrothermal decomposition of [Co(en)3] (NO3)3 complex onto graphene oxide nanosheets. The as-prepared nanocomposite (denoted as GO/Co3O4) was structurally characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopies (TEM and SEM), energy dispersive X-ray (EDX) spectroscopy, magnetic measurements, and N2 adsorption-desorption analysis. The results demonstrated successful immobilization of Co3O4 nanoparticles with an average diameter size of around 12.5 nm on the surface of graphene oxide nanosheets. The adsorption performance of GO/Co3O4 nanocomposite was investigated towards different organic dyes in aqueous solutions. The results displayed that the adsorption rate of the GO/Co3O4 nanocomposite was 98% for methylene blue (MB) in 12 min, and 66% and 45% for Rhodamine B (RhB) and methyl orange (MO) in 40 min, respectively. The effects of various important parameters including adsorbent dosage, contact time, pH, and temperature on the adsorption process were investigated in detail. The equilibrium adsorption data were better fitted by Langmuir isotherm. Adsorption kinetics is well-modeled using pseudo-second-order model. Different thermodynamic parameters indicated that the adsorption process was physisorption and spontaneous. The findings of the present work highlighted facile fabrication of GO/Co3O4 and its application for rapid and efficient removal of MB from wastewater.