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Waste Chinese Hickory husk biomass was used as a precursor in the preparation of low-cost ac-tivated carbon by ZnCl2 activation. The activated carbon was to be used for the removal of both cati-onic and anionic dyes – methylene blue (MB) and methyl orange (MO). The preparation parameters,including impregnation ratio (the mass ratio of ZnCl2 to the precursor), the activation temperature,the activation time and the impregnation time, were evaluated. The Taguchi method, in combinationwith analysis of variance (ANOVA), was used to determine the effects of the preparation parameterson the dye adsorptive capacities of the activated carbon, and to optimize preparation conditions withthe goal of maximizing its adsorptive capacities. The optimized conditions were an impregnation ra-tio of 2.0 g/g, an activation temperature of 550 ºC and an activation time of 60 min. In such an opti-mal combination of parameters, the adsorption of MB and MO was expected to reach approximately400 mg/g and 900 mg/g, respectively. The activation temperature had the most significant effect onthe carbon capacity to adsorb MB and MO. The impregnation ratio had a significant effect on the ad-sorption of both dyes with the trend towards higher adsorption at higher impregnation ratio, while theactivation time and the impregnation time were found to be insignificant
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