Activated carbons with well-developed microporosity prepared from Phragmites australis by potassium silicate activation

•K2SiO3 as a new activating agent was employed to produce activated carbon.•Activated carbons prepared by K2SiO3 were concentrated microporous.•The carbon activated by K2SiO3 had relatively large surface area.•The pore structure and surface characteristics were investigated.

Potassium silicate (K2SiO3) was employed as new activating agent for preparing activated carbons with well-developed microporous structure from a renewable source (Phragmites australis, PA). The effects of chemical impregnation ratio (mass of K2SiO3: PA, 1.0–2.5) and activation temperature (450–800 °C) on the properties of activated carbons were investigated. Porous textures and surface morphologies of the carbons were characterized by N2 adsorption/desorption and scanning electron microscopy (SEM). The activation was simulated by thermo-gravimetric analysis. In general, under the experimental conditions investigated, the highest surface area (721 m2/g) of activated carbons reached at activation temperature of 600 °C and impregnation ratio of 1.5. The produced carbons were mainly microporous and the majority of pore widths of the carbons were below 4 nm. These results indicated that K2SiO3 could be used as a new activating agent to produce activated carbon.