Preparation of bamboo-based mesoporous activated carbon by phosphoric acid activation

Abstract

Mesoporous activated carbons (ACs) were prepared from bamboo by phosphoric acid activation, and the optimum activation conditions such as impregnation ratio (H₃PO₄/bamboo ratio) and activation temperature were examined. The pore structure of the ACs was determined by N₂ adsorption-desorption isotherms. The results showed that the AC prepared using an impregnation ratio of 3 g/g and an activation temperature of 500 °C had the highest mesopore volume of 0.93 cm³/g. For further development of pores in AC, alkali pretreatment of the bamboo by soaking in aqueous sodium hydroxide was conducted and the pretreated bamboo was then activated with phosphoric acid under the optimum conditions. The influences of alkali pretreatment on the components of the raw material and the pore structure of the AC were examined, and the properties of bamboo before and after alkali pretreatment were also evaluated by thermogravimetric analysis and scanning electron microscopy. As a result, the possibility of the elution of hemicellulose and lignin from bamboo by alkali pretreatment was suggested. The AC prepared from alkali-pretreated bamboo had a mesopore volume of as high as 1.50 cm³/g, suggesting that the elution of hemicellulose and lignin from the raw material contributes to the development of mesopores by phosphoric acid activation.