Fabrication of cotton textile waste-based magnetic activated carbon using FeCl3 activation by the Box-Behnken design: optimization and characteristics

Cotton textile waste-based magnetic activated carbon was prepared via simultaneous activation-pyrolysis using FeCl3 as a novel activating agent. The response surface methodology based on the Box-Behnken design method was applied to optimize the preparation parameters and predict the specific surface area of the samples. The optimal activated carbon was obtained at a mass ratio of FeCl3/CTW, activation time and activation temperature of 1.62:1, 1 h and 700 degrees C, respectively. The experimental maximum yield and iodine adsorptive value (32.66% and 714.55 mg g(-1)) of the resultant carbon were close to that of the predicated response values (34.85% and 783.75 mg g(-1)), respectively. SEM, N-2 adsorption-desorption isotherms, XRD, PPMS, FTIR and pH(pzc) measurements were conducted to analyze the physicochemical characteristics of the optimal sample. The results showed that the carbon matrix had a high specific surface area of 837.39 m(2) g(-1) with abundant micropores and acidic surface functional groups, and the saturation magnetization (Ms) was 5.2 emu g(-1) due to the formation of Fe3O4. The maximum adsorption of Cr(vi) by the carbon reached 212.77 mg g(-1). Furthermore, the addition of FeCl3 lowered the pyrolytic carbonization temperature and inhibited the generation of volatiles in the activation-pyrolysis process. Meanwhile, the formation of Fe2O3 and Fe3O4 derived from FeCl3 was beneficial for the development of vast micropores.