Preparation and characterization of activated carbon derived from deashing coal slime with ZnCl2 activation

Activated carbon (AC) was successfully synthesized through flotation deashing combined with ZnCl2 activation using coal slime (CS) as the raw material. The results showed that flotation can effectively decrease the ash content of CS and increase the amount of micropores, and further enhance the adsorption amounts of methylene blue (MB) and iodine onto prepared AC. Single factor experiments and response surface methodology were employed to obtain the optimal preparation conditions: impregnation ratio of 1.2, impregnation time of 18 h, activation temperature of 485 ℃, activation time of 90 min, nitrogen flow of 100 mL·min−1 and heating rate of 5 ℃·min−1. The deashing coal slime activated carbon obtained under optimal conditions (DCSACop) shows high SBET of 918.15 m2·g−1 and VT of 0.511 cm3·g−1, and exhibits excellent adsorption performance (125 mg·g−1 for MB and 869 mg·g−1 for iodine). Besides, oxygen-containing functional groups such as C-O, CO and -COOH were detected on the surface of DCSACop. This approach supplied a potential and effective material for AC preparation, which is very promising in terms of technical, economic, and environmental feasibilities.