Lab-to-atmosphere simulation of adsorption dynamics and service lifetime prediction for MOF-199 with sub-ppm level hydrogen sulfide in mono and ternary phase

Abstract

Lab-scale air purification tests typically use unrealistically high concentrations (e.g., hundreds of ppm) of pollutants to quickly establish adsorption equilibria, whereas their real indoor concentrations rarely exceed one ppm. This large gap in concentration levels complicates scaling lab data to real-world scenarios. This study bridges the gap by experimentally evaluating adsorption breakthrough of MOF-199 packed bed for H<inf>2</inf>S, either in its single-phase or in ternary phase with formaldehyde and toluene vapors. Tests span both low (0.1–1 ppm) and high (10–50 ppm) concentrations to mimic indoor-to-outdoor variations. Low-level H₂S adsorption behavior is then accurately interpreted using the high-level experimental data combined with the semi-empirical Yoon-Nelson model and multiple isotherms. Experimental kinetics and in-situ spectroscopy analysis confirm that H<inf>2</inf>S adsorption onto MOF-199 is governed by chemisorption at active Cu2+ sites, as supported by density functional theory calculations. Competitive adsorption in ternary mixtures significantly reduces H<inf>2</inf>S uptake by MOF-199 due to molecular interactions and steric hindrance among co-adsorbates for these limited active sites. Such overlapping between chemisorptive and physisorptive interactions causes site-blocking, as confirmed both experimentally and theoretically. The Extended-Freundlich best describes this equilibrium, highlighting the heterogeneous nature of MOF-199. Combining Yoon–Nelson dynamics with Freundlich equilibrium, the adsorbent's service lifetime is projected at 1149 and 889 min at 0.1 ppm H<inf>2</inf>S for single- and ternary-phase systems, respectively. This integrated experimental-modeling framework effectively bridges lab-scale studies to real-world environments for complex pollutant interactions, enabling the predictive design of affinity and lifetime for MOF-199-based adsorbents employed in air purification systems