Textural characteristics of activated carbon by single step CO₂ activation from coconut shells

The use of coconut shells as feedstock for the preparation of activated carbons is well adopted industrially, using conventionally two stage activation process, either using steam or CO₂ as the activating agent. The present study attempts to utilize a one-step CO₂ activation to prepare activated carbon from coconut shell, which has received far less scientific attention. Experimental results show that activation temperature, CO₂ flow-rate, holding time and heating rates have significant effects on BET surface area, micropore volume and pore size distribution (PSD). The optimum conditions for activation have been found to be an activation temperature of 900 °C, a CO₂ flow-rate of 200 cm³/min, a holding time of 140 min, and a heating rate of 10 °C/min. The optimum conditions yielded an activated carbon with a BET surface areas of 1667 m²/g and micropore volume of 0.8949 cm³/g, which are significantly higher than the activated carbon produced either using two stage activation process or one-step steam/CO₂ activation for other precursors.