RESUMO
Graphene oxide (GO) was synthetized from graphite oxidation via the modified Hummers method. Afterwards, the GO was functionalized with diethylenetriamine (DETA) and FeCl3 to obtain the novel amino-iron oxide functionalized graphene (GO-NH2-Fe3O4). FTIR, XRD, SEM with EDX, and Raman spectroscopy were performed to characterize both GO and GO-NH2-Fe3O4. The GO-NH2-Fe3O4 was then evaluated as adsorbent of the cationic dye Methylene Blue (MB); analysis of the point of zero net charge (pHPZC) and pH effect showed that the GO-NH2-Fe3O4 pHPZC was 8.2; hence, the MB adsorption was higher at pH 12.0. Adsorption kinetics studies indicated that the system reached the equilibrium state after 5 min, with adsorption capacity at equilibrium (qe) and kinetic constant (kS) of 966.39 mg g-1 and 3.17â10-2 g mg-1 min-1, respectively; moreover, the pseudo-second-order model was better fitted to the experimental data. Equilibrium studies showed maximum adsorption capacity of 1047.81 mg g-1; furthermore, Langmuir isotherm better fitted the adsorption. Recycling experiments showed that the GO-NH2-Fe3O4 maintained the MB removal rate above 95% after 10 cycles. All the results showed sorbent high adsorption capacity and outstanding regeneration capability and evidenced the employment of novel GO-NH2-Fe3O4 as a profitable adsorbent of textile dyes.