Adsorption behaviors of phenol onto gasification residual cokes with different structural and surface properties

摘要

With steam and CO_2 as gasification agents, four types of gasification cokes were prepared from lignite and anthracite to investigate the adsorption behaviors of phenol onto cokes with different structural and surface properties. The textural parameters indicated that the prepared coke samples presented specific surface areas of 155.37-573.52 m~2/g and total pore volumes of 0.080-0.422 cm~3/g. The presence of phenolic, carboxylic, lactonic, and basic groups in samples was identified by Boehm titration. For the same type of coal, cokes prepared by steam presented a higher surface area and pore volume, and lower concentrations of both acidic and total functional groups compared with those of cokes prepared by CO_2. In the phenol adsorption tests, cokes prepared by steam showed better removal efficiency, reaching approximately 100% for 1 h of contact time. Coke samples prepared from lignite by steam presented the maximum adsorption capacity of 77.22 mg/g. The adsorption capacity increased as the concentrations of basic groups increased, but decreased with the increase in both acidic groups and the ratio of acidic to basic groups. Phenol adsorption was correctly adjusted by the pseudo-second-order equation, with the corresponding coefficient (R~2) reaching approximately 1, and fitted with the Langmuir, Temkin, and Freundlich models.