Practical strategies to address the moisture barriers in the adsorption of aromatic volatile organic compounds in air

Abstract

Aromatic volatile organic compounds (AVOCs) are well-known pollutants that exist ubiquitously in both indoor and outdoor environments. Adsorption is yet employed most preferably for the mitigation of AVOCs with multiple merits (e.g., facile operation and low cost) among various technological options developed based on recovery or destruction principles. The adsorption of AVOCs is generally suppressed by the presence of other components like water vapor, while their interactions can also have a positive effect (e.g., in terms of reverse polarities such as between (polar) water and (non or weakly polar) AVOCs). It is thus possible to considerably improve the removal potential (e.g., adsorption capability and selectivity) of sorbents against AVOCs even under wet conditions. In this review, the basic aspects of AVOC adsorption in the presence of water vapor are discussed using benzene and toluene as model compounds. In this context, AVOC removal performance of adsorbents is assessed between wet and dry conditions in terms of adsorption capacity (Q), partition coefficient (PC), and capacity retention (Q_wet/Q_dry) after being sorted into three groups (i.e., AC-based, MOF-based, and miscellaneous adsorbents). As a result, a number of adsorbents with suitable pore size, high hydrophobicity, or abundant functional groups (e.g., BUT-55 and AC-MA) are identified to perform well under both dry and humid conditions. This study offers forward-looking insights into the establishment of advanced strategies to design high-performance sorbent materials against AVOCs under real-world humid conditions.