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Designing selective sorbent materials to sequestrate toxic oxoanions with weaker binding tendency, especially oxoanions of selenium and arsenic (Se(IV)/Se(VI)/As(V)) is an arduous challenge. Herein, we demonstrate molecular shape recognition aided...

We show how expanded Wang–Landau simulations can be used to study the adsorption of methane–ethane mixtures in COF-102, COF-105, and COF-108. This approach has several advantages. First, a single simulation run is performed to determine key thermodynamic properties such as the adsorption isotherms and selectivity. Second, the combination of the expanded method with the Wang–Landau sampling in the grand-canonical ensemble provides direct access to the grand potential Ω = −k B T ln­[Θ­(μ1,μ2,V,T)] via a numerical evaluation of the grand-canonical partition function. From there, we calculate several thermodynamic quantities of adsorption, including the Gibbs free energy, enthalpy, and entropy, which give important insights into the mechanism of adsorption for the methane–ethane mixtures in covalent organic frameworks (COFs). In particular, using a solution thermodynamics approach, we identify a direct correlation between the separation efficiency (selectivity) of a given COF and its energetic efficiency (through desorption free energy calculations) for the methane/ethane mixture, which in turn, allows us to rank the different COFs on the basis of their methane/ethane separation performance.