Preparation and DEA removal performance of iron-modified activated carbon

Activated carbon (AC) was modified in this study using the impregnation roasting method for the preparation of iron-modified AC (Fe/AC), and the diethylamine (DEA) removal efficiency of Fe/AC was characterized by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller specific surface area analysis. The orthogonal experiment showed that the optimum conditions for the preparation of Fe/AC were as follows: calcination temperature, 500 °C; Fe₂(SO₄)₃ concentration, 0.3 mol L⁻¹; and calcination time, 3 h. The atomic percentage of Fe and S increased by 3.87 times and 1.23 times compared with that of AC, respectively. After modification, Fe(III) was aggregated on the Fe/AC carrier, and a new crystal phase was generated inside the Fe/AC. The specific surface area, pore volume, and internal porosity of Fe/AC were significantly increased. The highest DEA adsorption capacity of Fe/AC (3.55 mg g⁻¹) was ten times that of AC. The DEA adsorption on Fe/AC followed the quasi-second-order kinetic model, which involved both physical and chemical adsorption. The DEA adsorption on Fe/AC was in accordance with the Langmuir adsorption isotherm.