Hemin-based biomimetic synthesis of PANI@iron oxide and its adsorption of dyes

摘要

In this work, a polyaniline@ iron oxide (PANI@ iron oxide) composite was synthesized by using an ecofriendly hemin-based biomimetic method at mild conditions. The PANI@ iron oxide composite was characterized with scanning electron microscopy, UV-Vis, Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetric analysis, and its adsorption behavior was further tested. Results showed that PANI@ iron oxide can efficiently remove both anionic and cationic dyes from aqueous solution. For adsorption of dyes of methyl orange (MO) and rhodamine B (RhB) on PANI@ iron oxide, the kinetic data match well with pseudo-second-order model. The adsorption data were evaluated using Langmuir, Freundlich and Dubinin-Radushkevich isothermal models. For MO, high correlation coefficients (R-2) confirmed the validity of Langmuir isotherm, with monolayer adsorption capacity of 63.89 mg g(-1). For RhB, the Freundlich isotherm was precisely fit the equilibrium data. The values of Delta H degrees and Delta G degrees in the thermodynamic parameters indicated that the adsorption of dyes is endothermic and spontaneous. The value of Delta S degrees revealed that randomness at the solid-solution interface increases. NaOH solution was effective for desorption of dyes from PANI@ iron oxide. For PANI, dedoping process happened during desorption, and then the structure and charge changed during desorption process.