Hematite iron oxide nanoparticles (α-Fe2O3): Synthesis and modelling adsorption of malachite green

Abstract

To study themalachite green(MG) removal from aqueous solution, iron oxide was prepared from iron(III) nitrate nonahydrate (Fe(NO3)3, 9H2O) and ammonium hydroxide (NH4OH). The Fe2O3characterizationwas examined by X-ray diffraction spectroscopy (XRD), Brunauer Emmett- Teller (BET) specific surface area measurements and Fourier transform infrared (FT-IR) spectroscopy. The data of malachite green Kinetics adsorptions, show that the adsorption followed pseudo-second order kinetics. For concentrations below 6.10−4 mol/l, MG solution was almost completely decolorized after 45 min. The elimination percentage reached 86.13% for the concentration 6.10−4 mol/l and 25 mg of the Hematite. The experimental isotherms were analyzed with Langmuir, Freundlich and Redlich–Peterson using non-linear regression. The results showed that the Freundlich isotherms best-fit the equilibrium data. The thermodynamic study has shown that MG adsorption on Hematite is endothermic (ΔH°>0); it increases with temperature. The negative ΔG° values showed that the MG adsorption process on the Hematite is spontaneous. However, the positive value of ΔS° indicates the increase in Hematite-solution interface disorder at the time of MG fixation.