Browsing by Author "Haeri Nejad, Masoud"

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    Rapid screening and optimization of adsorbents by combining molecular simulation with rapid experimental methods
    (University of New Brunswick, 2024-10) Haeri Nejad, Masoud; Eić, Mladen
    Adsorption has proved to be an efficient means for removal of pollutants from the atmosphere. In addition to traditional adsorbents, such as silica gel, activated carbon and zeolites, new adsorbents have been introduced which include the metal-organic frameworks (MOF’s). The number of MOF structures is enormous and therefore ranking them for any specific application requires time-saving approaches. In this work, a novel approach dubbed “rapid screening” was introduced. It consists of (1) molecular simulation for prediction of adsorption isotherms followed by (2) the rapid experimental technique of the zero-length-column chromatography (ZLC) for isotherm confirmation. This approach was applied to the example case of screening and modifying metal-organic frameworks (MOFs) adsorbents to remove wasted inhalation anesthetic agents (IAA). IAA adsorption isotherms for three MOFs were predicted using molecular simulation (MS). For successful simulation of these large, branched, and polar adsorbates, an all-atom force field was also developed which accounted for the flexibility of the adsorbate IAA molecules. Using Continuous Fractional Component Monte Carlo (CFCMC) algorithms proved crucial to speed up the simulations. Predictions from MS results were subsequently verified by performing experimental adsorption measurements using traditional methods followed by the faster ZLC technique, with necessary modifications for vapors. ZLC was shown to be able to replace the traditional volumetric or gravimetric adsorption methods with acceptable accuracy. Next, the utility of rapid screening approach was verified for structural modification of a promising adsorbent for enhancing its IAA removal capability. Several structural modifications, including grafting, anion exchange and functionalization of benzene rings were proposed to the alter the pristine structure. New procedures were developed to create of new crystal information files (CIFs) for the modified structures to replace the CIF for the pristine structure as input to molecular simulations. The MS- predicted a two-fold of IAA adsorption capacity for MIL-101-Cr@NH3 (X=F-, OH-) compared with the unmodified structure. Experimental syntheses and rapid ZLC measurements confirmed this prediction. This approach, presented as proof of concept, is applicable to a larger number of materials by procuring or performing syntheses only of those structures that molecular-simulation screening has selected as the most promising adsorbent.