Preparation and characterization of activated carbon from oil palm wood and its evaluation on Methylene blue adsorption

Abstract

Activated carbons were prepared from the biomass of oil palm wood (OPW) via two stages, pyrolysis and physical activation, using an environmentally friendly pyrolysis pilot plant, and an activation pilot plant was studied. The latter uses the outlet flue gases from limestone calcination process as activating agents. Experimental results showed that pyrolysis and activation conditions leading to various final average temperatures had significant effect on the properties of activated carbons prepared. Suitable pyrolysis operating conditions of 7 m 3 h −1 airflow rate for 4 h until final average pyrolysis temperature 390 °C and activation conditions of 7.45 kg limestone calcined with airflow rate 202.4 ml s −1 for 3.5 h until final average activation temperature of 806 °C produced an activated carbon yield of 13.7%, 68.3% fixed carbon, 16.9% volatile matters, 4.3% ash, and 10.6% moisture, and 1084 m 2 g −1 BET surface area, and a micropore surface area of 931.6 m 2 g −1 was obtained. Methylene blue adsorption was tested and 90.9 mg g −1 maximum adsorption capacity was found. The high micropore fraction, N 2 adsorption isotherm and SEM showed that these activated carbons possessed intricate pore network comprising micropores and narrow mesopores. FTIR characterization indicated that pyrolysis and activation temperatures affected the surface functional groups and maximum Methylene blue adsorption was dependent on BET surface area.