Clay/starch/Fe3O4 nanocomposite as an efficient adsorbent for the removal of methyl violet dye from aqueous media

Abstract

ABSTRACT The purpose of this study was to eliminate methyl violet (MV) dye from aqueous media using clay/starch/iron oxide composite. Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and energy-dispersive X-ray/mapping (EDX/Map) analyses were used to determine the physical and structural properties of the composite. BET and DLS analyses indicated that the specific surface area and the average particle size of the composite were 74.27 m2/g and 179.6 nm, respectively. Then, the impact of various parameters was investigated on the sorption of MV dye. The results showed that the highest removal efficiency of MV dye (99.73%) was obtained at pH 9, contact time of 150 min, temperature of 25°C, initial dye concentration of 10 mg/L and composite dosage of 1.5 g/L, which indicated a significant sorption efficiency. The equilibrium behaviour of the sorption process was investigated using Freundlich, Langmuir, and Temkin isotherm models, which the Freundlich model was better fitted with the laboratory data. Also, by using the Langmuir model, the maximum sorption capacity of MV dye was obtained 29.67 mg/g, which was an appropriate sorption capacity. Moreover, various kinetic models were used to evaluate the kinetic data, including pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models, which the pseudo-second-order kinetic model could better describe the kinetic behaviour of the sorption process. Furthermore, the thermodynamic study showed that the removal of MV dye using the clay/starch/iron oxide composite was exothermic.