Influence of Lignin on the Pore Structure of Activated Carbon by H_3PO_4 Activation

Effect of lignin on the porous properties of activated carbon produced by H3PO4 activation has been investigated using sawdusts of poplar,larch and flax as starting materials.Lignin was removed by acetic acid-sodium chlorite method.The surface area and pore structure of obtained activated carbon were analyzed by H2-TPD.The adsorption properties were identified by iodine and methylene blue adsorption.Thermal behavior of the raw material was compared with the product after lignin removal by TG/DTG analysis.The results showed that with removal of lignin,the BET surface area,total pore volume and external surface area of activated carbon were decreased.Removal of lignin from wood materials was beneficial for the increment of micropore volume and surface area of micropore in activated carbon.The results of iodine and methylene blue adsorption were also demonstrated.Thermogravimetric results showed that the thermostability of raw material was decreased after removal of lignin.