Design and photo-Fenton performance of Graphene/CuS/Fe3O4 tertiary nanocomposites for Rhodamine B degradation
Renata Matos, Iwona Kuźniarska‐Biernacka, Mariana Rocha, J.H. Belo, João P. Araújo, Ana C. Estrada, Joana L. Lopes, Tushti Shah, Brian A. Korgel, Clara Pereira, Tito Trindade, Cristina Freire
Abstract
This study describes nanocomposites of graphene flakes (GF) combined with CuS, Fe3O4 and CuS−Fe3O4 nanoparticles prepared by wet chemical methods. The Fe3O4 and/or CuS nanoparticles were directly anchored onto GF without requiring additional chemical treatment. The composition, structure and morphology of the nanocomposites, as well as of the pristine GF and metal oxide/sulfide nanoparticles were characterised by X − ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), powder X − ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results confirmed the successful attachment of CuS nanophases (size range: 23.7–50.1 nm) and/or Fe3O4 nanoparticles (size range: 10.6–15.8 nm). The adsorption and photocatalytic properties of the GF−based nanocomposites were evaluated at room temperature using Rhodamine B (RhB) as a model contaminant. Theoretical models were fitted to the adsorption kinetic results using the pseudo-first-order, pseudo-second-order and Elovich equations, while the adsorption mechanism was determined using the intraparticle diffusion, Bangham and Boyd models. The RhB adsorption efficiency was 6.5% for [email protected]−Fe3O4 after 180 min contact time, whereas for the other materials was significantly higher: 97.6%, 60.9% and 31.9% for GF, [email protected] and [email protected]3O4, respectively. The adsorption capacity of GF and composites fitted the pseudo−second−order kinetic and Elovich models. The influence of the nanostructures composition on the corresponding photocatalytic activity in the degradation of RhB under a 150 W halogen lamp was also evaluated. The [email protected]−Fe3O4 nanocomposite totally eliminated the dissolved RhB after 60 min irradiation, whereas the [email protected], [email protected]3O4 and pristine Fe3O4 removed 75.6%, 80.9% and 30.8%, respectively, after 180 min irradiation. It was found that the photocatalytic behaviour of the composites was best described by the first−order kinetic model. The rate constant of the photocatalytic RhB removal for [email protected]−Fe3O4 (k = 7.05 ×10−2 min−1) was 2.1, 5.1 and 15.0 times higher than those obtained for [email protected], [email protected]3O4 and pristine Fe3O4, respectively, after 60 min of visible light irradiation.