effect of silica extraction on the porous structure and surface area of activated carbon prepared from rice wastes

The present work is based on the possibility of the simultaneous extraction of silica and activated carbon as two value-added chemical products from rice wastes (straw and husk)# the purpose of this work is to study the effects of silica impurities of the raw materials on the properties of the produced activated carbon# it was found that silica extraction after activation of the raw materials through the presented procedure could be beneficial for improving the porosity of the activated carbon# chemical activation of rice wastes ash was carried out using koh at the impregnation ratio of 0#5 under activation temperature of 800 °c for 1 h# in order to silica extraction, activation experiments were followed by an additional step: exposing the activated ash to reflux treatment in the presence of hydrochloric acid# the percentages of silica extraction from rice husk- and rice straw-based activated carbon under the certain operating conditions were 66 and 83%, respectively# in both cases, silica elimination from the activated ash increased the specific surface area of active carbons (from 521 to 947 m2/g for rice husk-based and from 499 to 1252 m2/g for rice straw-based activated carbon)#