Biocompatible MOFs for Storage and Separation of O₂: A Molecular Simulation Study

Abstract

Metal organic frameworks (MOFs) are great candidates for capturing O2 due to their highly porous structures and tunable physical and chemical properties. In this study, we assessed the performance of 1525 biocompatible MOFs which have endogenous linkers and nontoxic metal centers for adsorption-based and membrane-based O2 separation and also for high-pressure O2 storage. We initially computed Henry’s constants of O2 and N2 at zero coverage and 298 K by performing Grand Canonical Monte Carlo (GCMC) simulations and estimated infinite dilution adsorption selectivities for O2/N2 mixture. We performed binary mixture GCMC simulations for the top 15 candidates at various pressures and 298 K and compared mixture adsorption selectivities with those obtained from infinite dilution. We then estimated O2 working capacities of 315 biocompatible MOFs obtained at 298 K and 140 bar for storage and 5 bar for release pressures. Our results showed that 15 biocompatible MOFs outperform gravimetric O2 working capacities of the traditional adsorbent materials such as activated carbon and NaX and some common MOFs such as NU-125 and UMCM-152 at 298 K. We finally calculated O2 and N2 permeabilities and membrane selectivities of 45 promising MOF candidates for O2/N2 separation. Seventeen biocompatible MOF membranes were identified to exceed the Robeson’s upper bound established for polymers. This computational study will be useful to identify the promising biocompatible MOFs for storage and separation of O2. The bio-MOF library constructed in this study will also guide both experimental and computational studies for design and development of biocompatible MOFs for various medical applications.

Heterometallic Metal Organic Frameworks for Air Separation: A Computational Study

“…In all the GCMC simulations, four fundamental moves, namely translation, insertion, rotation, and deletion were attempted for adsorbate molecules. There are many reports existing in the literature validating the accuracy and reliability of the UFF and TraPPE force field combination for both MOF atoms without open metal sites and gas molecules in gas adsorption studies. , However, UFF fails to describe accurately the strong interaction between electron-donating adsorbates and open metal site MOFs. , In the present investigation, we aim to understand how homo- and heterometallic PCN-250 MOFs qualitatively affect the gas adsorption behavior. To accurately model the adsorbate–open metal sites interaction, either first-principles-based force fields or tuning the potential parameters comparing with experimental data needs to be performed and is beyond the scope of this work.…”

“…Here, the authors utilized UFF parameters plus an extended charge equilibration method as implemented in the RASPA program to predict the adsorption isotherm of O 2 and N 2 . They validated the force field parameters by comparing the simulated results with the experimental isotherms in several MOFs including Cu-BTC (open metal sites), IRMOF-1, IRMOF-3, UiO-66, and NU-125 . The adsorbent–adsorbate LJ interactions were computed in the real space, with a cutoff of 10.5 Å.…”

Selective Separation of Gases by Metal Organic Framework Materials (Mofs)

“…Therefore, society needs a strategy that consumes less energy but can still effectively separate O2/N2. On the other hand, there is only one computational study on predicting separation performance of MOF membranes in which membrane selectivity of 44 MOFs were found to be in the range of 1.5-11 [25]. As a result, even though the number of MOFs has been rapidly increasing and we still do not know separation performance limits of pure MOF membranes and MOF/polymer MMMs they have [26].…”

Post synthetically modified IRMOF-3 for efficient recovery and selective sensing of U(vi) from aqueous medium

“…42,43 Therefore, by using PSM strategy various organic functionalities (hard bases) can be incorporated in the pristine MOF to get the efficient extraction of U(VI) (hard acid) from aqueous medium. 44 In the last few years, iso-reticular metal-organic framework-3 (IRMOF-3) has been widely used for various applications such as heterogeneous catalysis, 45 gas storage/separation, 46 membranes, 47 and sensing of various metal ions, 48 due to its high surface area (BET reports 2200 m 2 g À1 ), stability towards atmosphere, high temperatures ($400 C) and its high luminescence property. Recently, the work carried out in our laboratory revealed the utility of PSM UiO-66-NH 2 graed with various functionalities for extraction of U(VI) from the aqueous medium.…”