Role of Ni(NO3)2 in the preparation of a magnetic coal-based activated carbon

The role of Ni(NO₃)₂ in the preparation of a magnetic activated carbon is reported in this paper. Magnetic coal-based activated carbons (MCAC) were prepared from Taixi anthracite with low ash content in the presence of Ni(NO₃)₂. The MCAC materials were characterized by a vibrating sample magnetometer (VSM), X-ray diffraction (XRD), a scanning electric microscope (SEM), and by N₂ adsorption. The cylindrical precursors and derived char were also subjected to thermogravimetric analysis to compare their behavior of weight losses during carbonization. The results show that MCAC has a larger surface area (1074 m²/g) and a higher pore volume (0.5792 cm³/g) with enhanced mesopore ratio (by about 10%). It also has a high saturation magnetization (1.6749 emu/g) and low coercivity (43.26 Oe), which allows the material to be magnetically separated. The MCAC is easily magnetized because the nickel salt is converted into Ni during carbonization and activation. Metallic Ni has a strong magnetism on account of electrostatic interaction. Added Ni(NO₃)₂ catalyzes the carbonization and activation process by accelerating burn off of the carbon, which contributes to the development of mesopores and macropores in the activated carbon.