Functional group directed tuning of highly recyclable Zr-MOF beads for preferential VOC adsorption

Volatile organic compounds (VOCs) are pollutants representing a great risk to human health. In this study, the adsorption performance of various zirconium metal organic frameworks (Zr-MOFs) and their composites with polyvinyl alcohol (PVA) was systematically evaluated toward preferential adsorption of polar, non-polar, and acidic VOCs. Zr-MOFs were selected for their ease of preparation, structural stability, tunability, and ability to incorporate diverse functional groups. The composites (Zr-MOFs@PVA) were fabricated via freeze granulation process by embedding Zr-MOFs in PVA at an optimized ratio. Among the Zr-MOF powders, UiO-66-NH₂ exhibited high adsorption for acetone, and isopropanol (IPA) due to its exposed –NH₂ groups, while highly defective UiO-66 demonstrated greater affinity for non-polar toluene, attributed to its high surface area and defect sites. Upon PVA incorporation, the Zr-MOFs@PVA beads exhibited significantly enhanced adsorption capacities for most VOCs tested, outperforming commercial activated carbon and zeolite adsorbents. This enhancement is attributed to the synergistic tuning of surface properties and pore environments induced by PVA. Notably, UiO-66@PVA beads showed the most versatile and consistent performance, demonstrating excellent reusability over 10 adsorption-desorption cycles without loss of crystallinity. Furthermore, under dynamic low-concentration, it achieved a toluene adsorption capacity of 314.45 mg/g. These findings highlight the potential of Zr-MOF@PVA composites as efficient and reusable VOC adsorbent for air purification applications.