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.