Enhancement removal of Cr (VI) ion using magnetically modified MgO nanoparticles

The main aim of this study was to synthesize MgO/Fe3O4 nanocomposite to remove Cr (VI) ions or anion dichromate (Cr2O7)(2?) from aqueous media and determine best operating conditions such as temperature, contact time, nanocomposite concentration, and concentration of Cr (VI) in aqueous solution as well as pH on removal efficiency of chromium. Different analyzes such as BET, VSM, SEM, TEM, FTIR, XRD, and EDAX/MAP were used to characterize the MgO/Fe3O4 nanocomposite. The VSM analysis of Fe3O4 and MgO/Fe3O4 nanocomposite showed the superparamagnetic behavior of Fe3O4 nanoparticles. Also, BET analysis showed a specific area of 75.21 m(2) g(?1)r(?1). In addition, the results of the adsorption process showed that the best operating conditions for removing ion Cr (VI) using MgO/Fe3O4 nanocomposite including pH, contact time, temperature, initial concentration of chromium ion and adsorption dose were 3, 30 min, 25 ;C, 10 mg L-?1 and 1.5 g L-?1 respectively, which in this case the removal efficiency was 97.73%. Moreover, the adsorption process of Cr (VI) was studied in terms of equilibrium, kinetic, and thermodynamic and the results revealed that the adsorption with MgO/Fe3O4 nanocomposite followed pseudo-second-order model. Besides, both Langmuir and Freundlich models were suitable to describe the equilibrium data. Furthermore, the maximum adsorption capacity using the Langmuir model was obtained 23.9 mg g(?1). Eventually, the thermodynamic study demonstrated that the removal of chromium (VI) by the MgO/Fe3O4 nanocomposite was exothermic.