Experimental Design To Optimize the Preparation of Activated Carbons from Herb Residues by Vacuum and Traditional ZnCl2 Chemical Activation

Doehlert matrix was used to optimize the experimental conditions for the preparation of activated carbons from herb residues by vacuum chemical activation and traditional chemical activation using ZnCl2 as activation agent. The effects of activation temperature and impregnation ratio, the most influential factors of ZnCl2 chemical activation, were studied. The obtained activated carbons were characterized by total yield and methylene blue and iodine adsorption value. Each response has been described by a second-order model, and the predicted model presented a good agreement with experimental data. The results showed that activated carbons prepared by vacuum chemical activation have higher yield and better adsorption capacity. The removal percentages of methylene blue for the two optimal activated carbons and a commercial activated carbon were determined. The activated carbon prepared by vacuum chemical activation exhibited the highest methylene blue removal efficiency.