Study On The Preparation Of Activated Carbon From Lignin-based Pitch And Adsorption Characterization

Activated carbon has been widely applied to the adsorption of toxic substances due to its high specific surface area and high pore volume.Currently,coconut shell,coal and bamboo are the usual raw materials of the activated carbon used.However,these activated carbons have relatively low specific surface area and pore volume with limited adsorption capacity.In this study,lignin-based pitch extracted from pulping waste liquor was used as the precursor to produce activated carbon with high specific surface area and high pore volume,and experiments on dynamic and static adsorption of benzene vapor were carried out.Firstly,two different preparation processes of activated carbon,physical activation method and chemical activation method,were discussed to determine the optimum conditions of the two preparation processes.Then in order to explore the adsorption behavior and mechanism of benzene vapor on the activated carbon,the dynamic adsorption and static adsorption experiments of benzene vapor on the prepared activated carbon were performed.In the physical activation method,the effect of carbonization temperature,activation temperature and activation time on specific surface area and yield of activated carbon was studied by orthogonal experiment.The results show when the carbonization temperature,the activation temperature and the activation time were set 700?,850? and 60 min,respectively,the specific surface area and total pore volume of the activated carbon were the largest,reaching 339 m2·g-1 and 0.139cm3·g-1,respectively.In the chemical activation method,the single-reason analysis method was employed to study the influence of the ratio of alkali to precursor,activation temperature and activation time on the specific surface area and total pore capacity of activated carbon.The results show when the ratio was 5:1 and the activation temperature was 850? and the activation time was 60 min,the specific surface area and total pore volume of activated carbon were the largest,3652 m2·g-1 and 2.35 cm3·g-1,respectively.The results of the dynamic adsorption experiments of benzene vapor show that the dynamic adsorption capacity of activated carbons produced by physical activation was low,the highest only 11.76%,which showed poor adsorption performance.However,the activated carbons prepared by chemical activation method exhibited excellent adsorption performance,and the dynamic adsorption capacity of benzene reached 124.49%.The results of the static adsorption experiments showed the static benzene adsorption capacity of the activated carbon PAC-5-850-60 was as high as 134.92% and was still over 130.00% after five cycles of adsorption/desorption,which far exceeded the static benzene adsorption performance of the three commercially available activated carbons.