Effect of the preparation method on the pore size distribution of activated carbon from coconut shell

The pore size distribution of activated carbon prepared from coconut shell employing different activation methods was investigated. “Physical” activation with pure CO2 at 800°C resulted in a bimodal pore size distribution featuring both the widest macropores and the narrowest micropores among the samples studied. The introduction of potassium phosphate as a catalyst for the gasification with CO2 led to a decrease in macropore volume and diameter and to a slight increase in micropore diameter. Wider micropores and significant mesoporosity resulted when employing “chemical” activation with phosphoric acid at a lower temperature (500°C). Surface area was found to increase with increasing median micropore diameter between about 7–15 Å. Three simple schemes were proposed depicting the effect of the preparation method on pore size distribution.