Enhanced Adsorption of Aromatic Volatile Organic Compounds on a Perchloro Covalent Triazine Framework through Multiple Intermolecular Interactions

Abstract

Volatile organic compounds (VOCs) may have short- and long-term adverse health effects. Especially, aromatic VOCs including benzene, toluene, ethylbenzene, and xylene (BTEX) are important indoor air pollutants. Developing highly efficient porous adsorbents with broad applicability remains a major challenge. In this study, a perchlorinated covalent-triazine framework (ClCTF-1-400) is prepared for adsorbing BTEX. ClCTF-1-400 is confirmed as a partially oxidized/chlorinated microporous covalent triazine framework through a variety of characterization. It is found that ClCTF-1-400 is reversible VOCs absorbent with very high absorption capacities, which can adsorb benzene (693 mg g^-1 ), toluene (621 mg g^-1 ), ethylbenzene (603 mg g^-1 ), o-xylene (500 mg g^-1 ), m-xylene (538 mg g^-1 ), and p-xylene (592 mg g^-1 ) at 25 °C and their saturated vapor pressure (≈ 1 kPa). ClCTF-1-400 is of higher adsorption capacities for all selected VOCs than activated carbon and other reported adsorbents. The adsorption mechanism is also inferred through theoretical calculation and in-site Fourier Transform Infrared (FTIR) spectroscopy. The observed excellent BTEX adsorption performance is attributed to the multiple weak interactions between the ClCTF-1-400 frameworks and aromatic molecules through multiple weak interactions (CH^… π and CCl^… π). The breakthrough experiment demonstrates ClCTF-1-400 has the potential for real VOCs pollutant removal in air.

Keywords: VOCs; adsorption; breakthrough; covalent-triazine frameworks; porous materials.