Construction of Core–Shell MOFs@COF Hybrids as a Platform for the Removal of UO₂²⁺ and Eu³⁺ Ions from Solution

Abstract

The binary nanocomposites of metal/covalent–organic frameworks (NH2-MIL-125­(Ti)@TpPa-1) were constructed by solvothermal method, which was developed as a multifunctional platform with adsorption and photocatalysis for radionuclides removal. The batch experiments and physicochemical property (FT-IR, XRD, SEM, TEM, XPS, etc.) corroborated: (i) core–shell NH2-MIL-125­(Ti)@TpPa-1 had a more stable, multilayer pore structure and abundant active functional groups; (ii) NH2-MIL-125­(Ti)@TpPa-1 had fast a removal rate, as well as a high adsorption capacity of 536.73 mg (UO2 2+)/g and 593.97 mg (Eu3+)/g; (iii) the pseudo-second-order and Langmuir model provided a more reasonable description, indicating the immobilization process was endothermic, spontaneous chemisorption; (iv) the adsorption mechanism was chelation and electrostatic attraction, ascribed to the nitrogen/oxygen-containing functional groups. These results illustrated that NH2-MIL-125­(Ti)@TpPa-1 was a prospective adsorbent for the remediation polluted by radionuclides. In addition, the research provided the theoretical basis for further investigation on the UO2 2+(VI) photoreduction.

Oxidation-Modulated CQDs Derived from Covalent Organic Frameworks as Enhanced Fluorescence Sensors for the Detection of Chromium(VI) and Ascorbic Acid

“…Due to the low content of the C–N bonds, and their binding energy similar to that of C–O bonds, the C–N and C–O bonds overlap and cannot be accurately identified (Figure a). This hypothesis is also supported by the high-resolution O 1s spectra (Figure b), which show that the binding energies of the two peaks located at 531.3 and 533.9 eV belong to CO and terminal OH (−C–N–H···O) in the keto form of TpPa-1. , After chemical tailoring, the terminal OH (−C–N–H···O) peak decreases and a new peak of C–O emerges at 532.6 eV. The result demonstrates the breakage of hydrogen bonds and partial hydrolysis during chemical tailoring.…”

Hybrid Porous Crystalline Materials from Metal Organic Frameworks and Covalent Organic Frameworks

“…[ 106 ] Furthermore, Hu and coworkers reported a more stable core–shell NH 2 ‐MIL‐125(Ti)@TpPa‐1 hybrid that functioned as an efficient adsorbent for radionuclide pollutants in wastewater. [ 107 ]…”

Structural Characteristics and Environmental Applications of Covalent Organic Frameworks

“…Removal of these metals from the effluents needs urgent attention. Hu et al proposed a composite material containing an MOF and a COF decorated with -NH 2 functionalities ((NH 2 -MIL-125(Ti)@TpPa-1) [113][114][115]. The composite material was able to remove both UO 2 2+ and Eu 3+ at fast rates of 536.73 mg/g and 593.97 mg/g respectively (Figure 4).…”