Performance Evaluation of Synthetic Goethite and Lepidocrocite Nanoadsorbents for the Removal of Aniline from a Model Liquid Fuel through Kinetic and Equilibrium Studies
Safoora Rahimi, Mansooreh Soleimani, Amir Reza Azadmehr
Abstract
Nowadays, the development of effective adsorbents to remove nitrogen-containing compounds from liquid fuels due to their various detrimental effects has generated significant interest. In the present paper, the adsorption performance of synthetic goethite and lepidocrocite, two different phases of iron oxy/hydroxides, for aniline removal was investigated through kinetic and thermodynamic studies. Adsorbents were synthesized and characterized using Fourier transform infrared spectroscopy, thermal gravimetric analysis/differential thermal gravimetry, field emission scanning electron microscope, and Brunauer–Emmett–Teller (BET) analysis. Kinetic studies indicated that the adsorption rates obeyed a pseudo-second-order model, and the dynamics of aniline adsorption was controlled by a hybrid mechanism containing both the surface and pore diffusion steps. BET results indicated the combination of micropores and mesopores in adsorbents’ structure. Adsorption over goethite included diffusion only into mesopores, while in the case of lepidocrocite, the micropores were also incorporated in the adsorption process. The equilibrium data were defined well with the Langmuir isotherm model. According to the obtained results, the Langmuir maximum adsorption capacities of goethite and lepidocrocite at 35 °C were 370.370 and 357.143 mg·g–1, respectively.