HKUST-1 infused woven cotton filter for enhanced adsorptive removal of toluene vapor from gaseous streams

Abstract

The utilization of metal–organic frameworks (MOFs) has recently increased in air/gas purification, especially for the adsorptive removal of volatile organic compounds (VOCs). However, the dynamic adsorption properties of fine powdery porous MOFs (e.g., HKUST-1) tend to suffer from a number of defects, especially a significant space velocity/pressure drop upon being loaded in a packed-bed adsorbent system. To overcome such shortcomings, a new fibrous MOF-based woven fiber sorbent filter was prepared via in-situ growth of HKUST-1 crystals on woven cotton substrates (thickness ≈1mm, diameter = 4.3 cm) at five different mass ratios of infused MOFs (i.e., 2.4, 6.6, 9.5, 31.2, and 41.8 wt/wt%). The adsorption efficacy of this filtration system was studied in reference to the packed bed sorbent using 1 Pa toluene vapor at near-ambient conditions. The relative adsorption performance of toluene was accounted for by the combined effects of the content of infused HKUST-1 (e.g., 41.8 > 31.2 > 9.5 > 6.6 > 2.4 wt/wt%) and the surface availability (m2 [g∙HKUST-1]−1) (e.g., 432 < 527 < 534 < 679 < 852, respectively: e.g., in relation to the increases in surface active sites). Based on the kinetics modeling, the adsorption mechanism was controlled dominantly by physisorption phenomena that consist of surface and pore diffusion as a rate-limiting step. This research offers valuable insights into the significance of morphological features of MOFs-based filtration media when employed for air purification by adsorption technique.