Preparation of Efficient Carbon-Based Adsorption Material Using Asphaltenes from Asphalt Rocks

In this work, the asphaltenes from natural Indonesia asphalt rocks were taken as raw materials for the preparation of micromesoporous enriched carbon material through pyrolysis (<500 °C) and KOH activation (<900 °C) processes. It is found that, during the pyrolysis process, the asphaltenes could be converted to noncondensable gas (36.02%), pyrolytic tar (26.57%), and residual char (37.44%). When the char was mixed together with KOH for heating, more carbons would be released due to the activation reaction, forming a carbon network. The optimal activation conditions were obtained at KOH/char ratio of 3:1 and 800 °C for 30 min. Results also show that almost all of the nitrogen atoms stay in the solid carbon during heating with little releasing to the gas or liquid products. The final obtained porous carbon materials are determined to possess a specific surface area of 1735 m2/g with rich micropores (∼2.0 nm). Instrumental characterizations show that there are abundant heteroatomic groups, including S═O, —OH, and —N═, on the activated carbon surface. Further tests by adsorption indicate that the adsorption of methylene blue on the porous carbon material is monolayer adsorption. The maximal adsorption capacity is determined to be at 556.00 mg/g, much higher than that of some commercial activated carbons. It is also indicated that the adsorption kinetics follows the pseudo-second-order kinetic model. These findings suggest that the asphaltene derived carbon material would be promising efficient adsorbents. It also sheds lights on the resourcilization of asphaltenes.