Synthesis of iron oxide nanoparticles modified mesoporous carbon and investigation of its application for removing dibenzothiophene from fuel model

Abstract

In this study, magnetic ordered mesoporous carbon (γ-Fe2O3/CMK-3) containing iron oxide nanoparticles embedded in the carbon walls by wet impregnation method was prepared and used as a high effective magnetic adsorbent to adsorb polyaromatic sulfur compound (dibenzothiophene). The structure and morphology of adsorbent were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption (BET), thermal gravimetric (TGA) and alternating gradient force magnetometer techniques (AGFM). These techniques illustrate that the maghemite nanoparticles have an average size of 10 ± 3 nm and are well distributed on the ordered mesoporous carbon host. After embedding maghemite nanoparticles, the uniformity of mesoporous framework of CMK-3 still remaining stable, which has an ordered two-dimensional hexagonal (p6mm) structure, high specific surface area, maxima pore size of 5.5 nm and large pore volume (up to 1.01 cm3 g−1). The γ-Fe2O3/CMK-3 nanocomposite shows superparamagnetic behavior with a saturation magnetization of 0.5 emu g−1, which makes it favorable compound for magnetic separation procedure. The resulting magnetic mesoporous nanocomposite was investigated for adsorption of dibenzothiophene (DBT) as a model sulfur compound in n-hexane as fuel model. Various factors influencing the adsorption of DBT, including adsorption temperature, contact time and initial DBT concentration were studied. The kinetic data was well described by pseudo-second-order kinetic model and the equilibrium adsorption data was fitted to the Langmuir thermodynamic model. In addition, the adsorbent could be regenerated by washing with toluene and over 85% adsorption capacity could be maintained after three regeneration cycles. The results confirmed that γ-Fe2O3/CMK-3 has the potential superiority in removal of DBT from fuel model with a maximum adsorption capacity of 67 mg DBT per gram of adsorbent and an easy magnetically separable process.