Photocatalytic and Electrocatalytic Extraction of Uranium by COFs: A Review

Abstract

The highly selective and effective enrichment of U(VI) from seawater and nuclear industry wastewater is important not only for nuclear power development and dependable energy source, but also for reducing the potential threat of radionuclides to the environment and human health. Covalent organic frameworks (COFs) are ideal materials for trapping U(VI) ions in aqueous solutions because of their advantages such as inherent porosity, strong skeleton, chemical stability, and good structural regularity. Herein, the most recent developments in the investigation of COFs for efficient preconcentration and separation of U(VI) by adsorption, photocatalysis, and electrocatalysis from seawater and radioactive wastewater are reviewed. The performance and related mechanisms of U(VI) interaction with COFs are carefully analyzed from the results of batch sorption experiments, the advanced spectroscopy analysis, and theoretical calculations. The potential and challenges of the present regarding the use of functional COFs for U(VI) extraction are described. Our aim is to provide insight and advice for the creation of innovative functional COFs for U(VI) extraction with high efficiency and selectivity in the future.

Identification of oxygen sites in β-ketoenamine-linked covalent organic frameworks for highly efficient uranium adsorption through experimental and theoretical studies

“…In the FT-IR spectrum of DQTP COF, the C]C and C-N characteristic peaks at 1554 and 1250 cm −1 appeared respectively, while the N-H stretching vibration peak vanished, implying the formation of a stable keto form of Schiff base. 22 The pore size distribution and specic surface area of DQTP COF were investigated from N 2 adsorption-desorption isotherm measurements at 77 K. As shown in Fig. 2(c), the plotted curves were in accordance with type-IV isotherm, and the adsorptiondesorption process exhibited traits of a type H4 hysteresis loop, which are expected to provide mesoporous properties to the adsorbent materials.…”

“…In the FT-IR spectrum of DQTP COF, the CC and C–N characteristic peaks at 1554 and 1250 cm −1 appeared respectively, while the N–H stretching vibration peak vanished, implying the formation of a stable keto form of Schiff base. 22…”

“…It possesses high crystallization, large specic surface area, well-dened porosity, and outstanding tunable scaffolds. [21][22][23][24][25] Tunable molecular design of various organic linkers enables the COFs as a novel platform among the myriad of research elds, such as energy storage, 26 sensors, 27 membrane separation, 28 adsorption, 29,30 and other applications. Among them, 2,6diaminoanthraquinone-1,3,5-triformylphloroglucinol, denoted as DQTP COF, is a type of COF material linked by b-ketoenamines through the Schiff base reaction of 1,3,5-triformylphloroglucinol (TFP) and 2,6-diaminoanthraquinone (DAAQ).…”

Extraction of Uranium by a Pyrazole-Based Porous Organic Polymer

“…On the other hand, nuclear wastewater contains a large amount of uranium, so it is important to recover uranium from nuclear wastewater. 3,4 Photocatalysis has a wide range of energy sources, mild reaction conditions, and no secondary pollution. In the past, scientists have applied photocatalytic technology to remove pollutants from water, and exciting results were obtained.…”

“…As a new type of clean energy, nuclear energy has been initially applied to production practice after decades of development. , However, nuclear energy also faces a shortage of raw materials (uranium resources), and uranium is toxic and radioactive, which can damage human tissues. On the other hand, nuclear wastewater contains a large amount of uranium, so it is important to recover uranium from nuclear wastewater. , …”