Optimization and preparation of sludge-based activated carbon by two-step pyrolysis and performance characteration

Sludge-based activated carbon was produced with sewage sludge from municipal wastewater treatment facility combined with corn straw as raw material by a two-step pyrolysis method through chemical activating ZnCl₂. First sludge was carbonized at 400°C for 60 min, then it was mixed with activator solution at a solid to solution ratio of 1:2. BET value and yield were observed according to the variation of temperature and the content of corn straw. Results showed that when activated carbon was produced under the condition of 25% corn straw content and 500°C pyrolysis temperature, the BET surface area achieved 756 m²/g. The yield presented a trend of slow dropping with increasing temperature. When activated carbon was prepared under the temperature of 450°C and corn straw content of 25%, yield attained the maximum value 43.1%.