Preparation and characterization of activated carbon from wool waste and the comparison of muffle furnace and microwave heating methods

The present study explored the utilization of wool waste (WW) for preparing activated carbon by muffle furnace (MFAC) and microwave (MAC) heating methods with phosphoric acid activation. MFAC was produced by activating at 550 °C for 40 min in muffle furnace. MAC was prepared with radiation power of 700 W and radiation time of 15 min. The physicochemical properties of the activated carbons were determined by N2 adsorption/desorption, Boehmʹs titration, and Fourier-transform infrared spectroscopy (FTIR). The sorption behaviors of the carbons toward Ni(II) were investigated through batch sorption experiments. MAC exhibited slightly larger surface area (519 m2/g) than MFAC (472 m2/g). However, results from Boehmʹs titration and FTIR suggested that MFAC contained more surface oxygen-containing functional groups than MAC. Sorption experiments indicated that MFAC presented better performance for Ni(II) sorption (17.87 mg/g) than MAC (6.09 mg/g). The sorption followed well the pseudo-second-order kinetic model and the sorption isotherms simulated well the Freundlich model for both of the carbons. Based on the physicochemical properties of activated carbons and the result of the sorption studies, oxygen-containing functional groups played an important role in the sorption of Ni(II). The likely important mechanisms for Ni(II) sorption onto MFAC and MAC were cation exchange and electrostatic attraction.