Underlying potential evaluation of the real-process applications of magnetic porous liquids

Abstract

It is possible to engineer permanent pores into a liquid instead of transient intermolecular pores found in all liquids, and thereby design and form porous liquids (PLs). A combination of porosity and fluidity has garnered attention in recent years due to its exceptional physicochemical properties. In the years since the concept was introduced in 2007 and the first examples demonstrated in 2015, significant advances have been made in all three types of PLs. As a result of these advances, researchers now understand their structure and properties better, and interesting improvements in gas uptake and molecular separation have been made. Recently, Type III PLs have attracted attention as low-loss materials for continuous CO₂ capture that can be adapted to industrial applications and are easy to synthesise and create from a wide variety of MOFs and solvents, with possibilities of creating stable PLs through different MOF modification methods. In spite of these advances, the regeneration and reusability of PLs have not been thoroughly investigated. This work aims to systematically explore the possibilities of implementing PLs in real-process applications using magnetic framework composites (MFCs) as porogens with the aid of a compatible non-penetrating solvent. This provided insights into the static and dynamic sorption and desorption breakthrough isotherms and cyclic sorption and desorption properties. The MFCs (MgFe₂O₄@ZIF-62) with different concentrations of magnetic nanoparticles (1–6 wt% of magnetic nanoparticles to ZIF-62 mass) were combined with a compatible non-penetrating solvent to create magnetic porous liquids (MPLs). By using MFC triggering in PLs, it has been demonstrated using 3 cycles that gases can be reversibly captured and released. In this way, these nanoheaters overcome the thermal insulation property of porogens in Type III PLs. Therefore, the amount of CO₂ released during three sorption–desorption cycles remained relatively constant. MPL's regeneration energies for 3 cycles were among the lowest observed for any adsorbent. The MPL's low energy consumption and high productivity across 3 cycles exceed those of any previously reported adsorbent. These findings demonstrate the amazing cyclic sorption and desorption properties of the MPL's triggering release of the captured CO₂, which have numerous potential applications in gas separation.