Introduction of Flexibility into a Metal–Organic Framework to Promote Hg(II) Capture through Adaptive Deformation

Abstract

The development of a practical Hg­(II) adsorbent is highly important for both environmental protection and public health. Herein, an adaptive metal–organic framework (MOF; FJI-H30) has been prepared from a highly flexible ligand [tris­(pyridin-4-ylmethyl)­amine] and Co­(SCN)2 with cheap Hg­(II) adsorption sites (SCN– groups) that not only has excellent chemical stability but also can capture Hg­(II) from aqueous solution with high adsorption capacity (705 mg g–1). Moreover, it also has good anti-interference ability and can be used repeatedly and large-scale prepared. Further researches demonstrate that the relatively high Hg­(II) adsorption capacity originates from the adsorbed Hg­(II)-induced deformation of FJI-H30, and such an adaptive deformation will reduce the potential repulsive forces between the adsorbed Hg­(II) ions, enabling almost all Hg­(II) absorption sites to adsorb Hg­(II) ions. Finally, how to induce the deformation of FJI-H30 by adsorbed Hg­(II) also has been studied in detail. Our work not only provides a practical Hg­(II) adsorbent for wastewater treatment but also offers a novel strategy for the design of novel MOFs for efficient heavy-metal-ion removal.

Functionalized Metal‐Organic Frameworks for Hg(II) and Cd(II) Capture: Progresses and Challenges

“…Introduction of both Hg(II) adsorption site and flexibility into a MOF may overcome such shortcoming. According with the above strategy, a flexible MOF ( FJI‐H30 ) based on a highly flexible ligand (TPMA) and Co(NCS) 2 was prepared by our group (Figure 6c, g) [65] . FJI‐H30 could effectively capture Hg(II) from water with a relative high adsorption capacity (705 mg g −1 ), in which the utilization ratio of SCN groups was about 99 %.…”

“…Copyright © 2016, Royal Society of Chemistry. (g) The network of FJI‐H30 ([Co 3 (SCN) 6 (TPMA) 4 ] n ) [65] . Copyright © 2020 American Chemical Society.…”

UiO-66-NHC(S)NHMe/Three-Dimensional Macroporous Carbon for Removal and Electrochemical Detection of Cd2+, Pb2+, Cu2+, and Hg2+

“…MIL-100­(Fe) was prepared to remove As 5+ . Some MOFs containing mercaptan or thioether functional groups were effective Hg 2+ scavengers. − Saleem et al found that after the UiO-66-NH 2 MOF was post-synthetically modified to introduce isothiocyanate (UiO-66-NHC­(S)­NHMe), maximum adsorption capacities for Hg 2+ reached 769 mg/g, which were 5 times higher than those of the thiol-functionalized Zr-DMBD MOF. However, MOFs are insoluble powdered materials and are easily accumulated in aqueous solution and on an electrode surface.…”

Water-Stable Amino-Functionalized Coordination Polymer for Efficient Hg2+ Capture

“…24,25 Selecting appropriate interacting groups as functional sites is an effective strategy to greatly promote Hg 2+ removal. 26 On the other hand, the stability of materials is an important factor restricting their practical application. Although intense ionic movements during adsorption have led to structural collapse and loss of single crystallinity, the selection of suitable MOFs may be a useful solution.…”

“…In previous reports, coordination polymers are regarded as excellent candidates for the next generation of adsorption materials owing to high porosity and regular pores. , Many functionalized MOFs and MOF-based mixed matrix membranes have been successfully developed and used to remove from water. , When some functional groups such as −NH 2 , S–CH 3 , , and −CONH– were introduced into the cavities, the polymer framework can show very high efficiency in removing metal ions and organic pollutants from industrial wastewater. , Selecting appropriate interacting groups as functional sites is an effective strategy to greatly promote Hg 2+ removal . On the other hand, the stability of materials is an important factor restricting their practical application.…”