Porous polymeric resin for adsorbing low concentration of VOCs: Unveiling adsorption mechanism and effect of VOCs’ molecular properties

The adsorption of 20 kinds of VOCs including n-alkanes, alcohols, esters, ketones, aromatics, chlorocarbons and cyclohexane on porous polymeric resin (PP-resin) were studied at low concentration by inverse gas chromatography (IGC). The adsorption partition coefficients and adsorption free energy of VOCs were calculated. A linear solvation energy relationship (LSER) model was employed to understand the adsorption mechanisms of VOCs on PP-resin. The results showed that hydroxyl groups on the surface of PP-resin resulted in the predominantly Lewis basicity on its surface. VOCs were adsorbed on the PP-resin mainly by dispersive interactions. Nevertheless, dipole-dipole/dipole-induced dipole interactions, hydrogen-bond acidity and hydrogen-bond basicity cannot be ignored especially for VOCs with polar groups. Among the adsorbates tested, methanol exhibited the highest specific interaction force (0.909) and cyclohexane was least only 0.038. It was also revealed that dispersive interactions were more important when longer carbon chain or larger molar volume of VOCs were adsorbed.