Preparation of Mesoporous Activated Carbons by Chemical Activation of Acid- and Base-Pretreated Bamboos for Removal of Bulky Dye Molecules

抄録

Mesoporous activated carbons were prepared from three types of bamboo materials, i.e. non-pretreated, acid-pretreated and base-pretreated bamboos, by H₃PO₄ and ZnCl₂ activation. Acid- and base-pretreatments of bamboo materials were performed using H₂SO₄ and NaOH, respectively, in order to alter bamboo components and enhance an activation effect. The change in bamboo components by acid- or base-pretreatment was examined by thermogravimetric analysis. The porous structure of prepared activated carbons was also characterized through N₂ adsorption-desorption isotherms at －196℃. The results showed that the base-pretreatment of raw materials had the positive effect on mesopore development during H₃PO₄ and ZnCl₂ activation processes, while such kind of effect by acid-pretreatment was observed only for ZnCl₂ activation. The most mesoporous sample prepared from base-pretreated bamboo by H₃PO₄ activation with the impregnation ratio of 6 g/g showed the S_BET, V_meso and D_ave values of 1380 m²/g, 1.54 cm³/g and 6.0 nm, respectively. The dye adsorption experiments were carried out through a batch test to evaluate each prepared activated carbon. Methylene blue and direct blue 71 were chosen as adsorbates. ZnCl₂ activated carbons had the better adsorption capacity for methylene blue compared to H₃PO₄ activated carbons, which were not well-suited for the methylene blue adsorption probably due to their smaller S_BET and positive charge on surface. The most mesoporous sample had the largest amount of direct blue 71 adsorption (0.97 mmol/g) among the all samples, suggesting that the prepared mesoporous activated carbons would be a valuable material for the removal of bulky dyes.