Synergistic Effect of Functionalization and Crystallinity in Nanoporous Organic Frameworks for Effective Removal of Metal Ions from Aqueous Solution

Abstract

In order to search effective adsorbents for removal of metal ions in water treatments, three nanoporous organic frameworks, TPPA, TPPA-SO 3 H, and TPBD-SO 3 H, with or without −SO 3 H functionalities were selected and synthesized by the Schiff base reactions of 1,3,5-triformylphloroglucinol (TP) and p-phenylenediamine (PA), p-phenylenediaminesulfonic acid (PA-SO 3 H), and 2,2′-benzidinedisulfonic acid (BD-SO 3 H), respectively. Characterizations revealed that both TPPA and TPPA-SO 3 H possess high crystallinity and porosity, while only amorphous powder with irregular pores of TPBD-SO 3 H was obtained. The Brunauer−Emmett−Teller surface areas of 425.3 and 297.5 m 2 /g for TPPA and TPPA-SO 3 H, respectively, were calculated, while only 45.1 m 2 /g was detected for TPBD-SO 3 H. Metal ion adsorption experiments revealed that among all three framework materials, TPPA-SO 3 H shows the best performances in adsorption capacities, removal efficiency, and adsorption rate to all of the tested metal ions, especially Fe 3+ , Cr 3+ , and Cd 2+ ions. Compared with the absence of −SO 3 H functionalities in TPPA and the amorphous nature of the extended framework material of TPBD-SO 3 H, the high performances of TPPA-SO 3 H should be ascribed to its synergistic effect of functionalization and crystallinity. This study revealed that besides the functional groups, the crystallinity of nanoporous organic frameworks is also a crucial factor in their applications.

Effective Iodine Adsorption by Nitrogen-Rich Nanoporous Covalent Organic Frameworks

“…Recently, a class of organic polymeric porous materials with crystalline and periodic structures, that is, covalent organic frameworks (COFs), − have shown highly promising potential in the applications of heterogeneous catalysis, − chemical sensing, bio-imaging, , and photodynamic therapy, − proton conduction, and energy storage, − as well as adsorption and separation to kinds of ions and molecules, − including iodine. − Due to their inherent porosity and strong covalent bonding of the organic components with light elements such as C, H, O, and N, COF materials not only show low density and relatively high stability but also display chemical tenability. − For instance, functional organic moieties with photoresponsive activity, proton-transport properties, and even chiral centers have been introduced into the COFs during the syntheses of precursors or post-modification of the constructed frameworks for photocatalysis, − proton conduction, ,− and asymmetric catalysis, − respectively. Previous works on iodine adsorption revealed that by decorating the framework with nitrogen-rich groups, the adsorption capacity of iodine can be significantly improved. − Thus, introducing nitrogen-rich groups into the COFs should be a feasible way for the fabrication of effective iodine adsorbents.…”

Lysozyme Carbo-Gel Integrated Repackable Miniaturized Microextraction Device: A Platform for Rapid Enrichment and Sensitive Detection of Multimetal Ions

“…The presence of another species with a similar charge had a minor to moderate interfering effect on the targeted metal analytes, causing lower maximum extraction capacities for selected metals, which resulted in the different trend Bi 3+ ≥ Pb 2+ > Ag + > Cd 2+ ≥ As 3+ > Co 2+ regarding the elution efficiency. The observed phenomenon presumably has two possible reasons: (1) high oxidation state of the central metal ion and (2) metal electronegativity (EN) . The EN plays an important role in the case of nonpure electrostatic extraction along with the oxidation state.…”

“…The observed phenomenon presumably has two possible reasons: (1) high oxidation state of the central metal ion and (2) metal electronegativity (EN). 32 The EN plays an important role in the case of nonpure electrostatic extraction along with the oxidation state. The EN of Pb 2+ is 2.33, compared to the EN of Bi 3+ of 2.02, however because Bi 3+ has a higher oxidation state, an almost equal extraction efficiency was seen.…”

New sulfonated covalent organic framework for highly effective As(III) removal from water

“…Their distinct structural features, including a large surface area, adjustable pore dimensions, and outstanding stability, render them particularly suitable for use in water purification applications [ [20] , [21] , [22] , [23] ]. Different molecules can be added or changed to tailor and enhance COFs at the level of atoms, which enables exact manipulation of their physical and chemical attributes to boost the effectiveness of pollutant extraction and the treatment of wastewater [ [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] ]. Within the field of separation science, the utilization of COFs has largely been dependent on their π–π stacking interactions and innate hydrophobic traits.…”