Carbon Deposition Pore-Narrowing Modification of Activated Carbon for Adsorption of Chlorinated Volatile Organic Compounds
Chlorinated volatile organic compounds (CVOCs) such as dichloromethane (DCM), dichloroethane (DCE), trichloroethylene (TCE), and chlorobenzene (CB) are hazardous air pollutants requiring efficient removal. This study modified a commercial activated carbon (AC) via high-temperature treatment and phenol cracking carbon deposition to tailor its pore structure for enhanced adsorption of small-molecule CVOCs. The modified material (AC-M) exhibited a significant increase in ultramicropore volume (<0.8 nm), leading to a 24.2% increase in DCM adsorption capacity under dry conditions and superior water vapor resistance. Surface oxygen-containing functional groups decreased, enhancing hydrophobicity and mitigating water cluster formation. Adsorption kinetics analysis revealed that AC-M had a 39% higher total adsorption rate constant for DCM and a 22% reduction in mass transfer zone height, indicating faster adsorption. However, for larger CVOCs (DCE, TCE, CB), adsorption capacities slightly decreased due to reduced specific surface area, suggesting their adsorption relies more on micropores of matching size. This work provides a theoretical basis for designing efficient adsorbents for small-molecule CVOCs control.