Adsorption and Regeneration of Volatile Organic Compounds (VOCs) on Coal-Based Activated Carbon by Ferric Nitrate Modification

In this study, the Heishan coal was used to prepare a series of activated carbon (AC) samples via a vapor deposition method. The effects of the Fe(NO3)(3)/coal weight ratio on the physicochemical properties of the activated carbon were systematically investigated, and the AC samples were analyzed by the N-2 adsorption-desorption technique, the scanning electron microscopy, the X-ray diffraction, the Raman spectroscopy, and the Fourier transform infrared spectroscopy. Furthermore, the adsorption properties of ethyl acetate were investigated. The results indicated that as the Fe(NO3)(3)/coal mass ratio increased from 1:8 to 1:2, the specific surface area, the total pore volume and the micropore volume initially increased and then decreased. The specific surface area increased from 560.86 m(2)/g to 685.90 m(2)/g, and then decreased to 299.56 m(2)/g. The total pore volume and micropore volume increased from 0.29 cm(3)/g and 0.17 cm(3)/g to 0.30 cm(3)/g and 0.22 cm(3)/g, and then decreased to 0.16 cm(3)/g and 0.10 cm(3)/g, respectively. The optimized ratio was 1:8. During the activation process, iron ions infiltrated the activated carbon to promote the development of the pore structure, the pore size of which was between 2.5 nm and 3 nm in daimeter. This approach could enhance the capacity for adsorption of ethyl acetate. It is worth noting that the ACs displaying the largest specific surface area and total pore volume (685.90 m(2)/g and 0.30 cm(3)/g) were formed under the optimized activation conditions (950 degrees C, 20%(volume) of CO2, ratio 1:5), and the maximum AC capacity for adsorption of ethyl acetate was 962.62 mg/g. After seven repeated thermal regeneration experiments, the saturated AC adsorption capacity was still above 90%.