Optimization of highly microporous activated carbon preparation from Moso bamboo using central composite design approach

Highly microporous activated carbons were prepared from Moso bamboo (Phyllostachys pubescens) using physical (steam) and chemical (KOH) activation. Increasing activation temperature and time was shown to increase the surface area and microporosity of activated carbons, which were further reduced due to over-gasification. Development of micropores was clearly observed based on N-2 adsorption isotherms. Steam activation temperature at 800 degrees C and activation time of 2.25 h can achieve large total surface area (S-BET) of 1135 m(2)/g and micropore volume of 0.521 cm(3)/g. For KOH activation (KOH/char mass ratio = 2), the 800 degrees C activation temperature and 2.25 h activation time resulted in S-BET of 1673 m(2)/g and micropore volume of 0.847 cm(3)/g. For KOH activation with a KOH/sample mass ratio = 4, 870 degrees C activation temperature and 1.27 h activation time enhanced S-BET to 2527 m(2)/g and micropore volume to 0.96 cm(3)/g. Central-composite design approach appeared to successfully acquire the optimal activation conditions, which can be set at 835 degrees C +/- 5% with an activation time of 1.75 h +/- 30% for both physical and chemical activation. The optimal conditions could cause the resulting bamboo activated carbons with the greatest S-BET and sufficient microporosity. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.