Experimental Study of the Accumulation Mechanism of Styrene in Activated Carbon with the Aid of Supercritical Solvent Extraction

During the purification of industrial organic emissions containing reactive volatile organic compounds (VOCs) such as styrene by activated carbon (AC) adsorption, it is a common phenomenon that desorption of VOCs from AC is hindered by heel, the VOCs, and/or VOC-derived matters accumulating in AC pores. Herein, heel was extracted with the aid of supercritical dichloromethane and was characterized in detail to identify its composition. Then, the thermal behavior and effects of heel on the pore structure, morphology, and surface chemistry of spent AC and regenerated AC were studied. The results show that the accumulating styrene in micropores reacted and formed a heel. The presence of metal elements and acidic functional groups may initiate or promote the polymerization of styrene. The dominant component of the heel was triphenylbenzene, and its formation process could be depicted by the Mayo polymerization mechanism.