Spectrophotometric studies on the uranyl-ascorbate complex

Razik, A. Abdel; Ali, Farman; Attia, Fatma

doi:10.1016/0026-265x(87)90161-5

Cited by 8 publications

(2 citation statements)

References 7 publications

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“…Prior studies have noted that U(VI) species and the photocatalyst surface properties are strongly correlated with H + concentration, , the increased H + concentration would affect the surface photocatalytic reaction . A lower removal efficiency was also be observed at pH 4, the reason is that ascorbic acid (H 2 A) stabilizes U(VI) in the [UO 2 HA] + form and makes U(VI) difficult to reduce when pH ≥ 4 …”

Section: Resultsmentioning

confidence: 99%

“…52 A lower removal efficiency was also be observed at pH 4, the reason is that ascorbic acid (H 2 A) stabilizes U(VI) in the [UO 2 HA] + form and makes U(VI) difficult to reduce when pH ≥ 4. 53 Surprisingly, from Figure 4c,d, the required irradiation time to achieve the highest removal percentage was significantly reduced from 8 h for imine COFs to 2 h for amide COFs, which indicated an impressive catalytic reduction rate of amide TFPPy−DP.…”

Section: Photocatalysis Reduction Of U(vi)mentioning

confidence: 87%

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Amide Linkages in Pyrene-Based Covalent Organic Frameworks toward Efficient Photocatalytic Reduction of Uranyl

Kang

Hang

Chen

et al. 2022

ACS Appl. Mater. Interfaces

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The bond linkages in covalent organic frameworks (COFs) partly determine its physical and chemical properties, thus affecting the photoreactive activity by influencing the generation of photoelectrons and the separation of excitons. Herein, pyrenebased amide COF 4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde−3,8-diamino-6-phenylphenanthridine (TFPPy−DP) was synthesized by postsynthetic modification of imine COFs. Due to the introduction of oxygen atoms into the framework and the change in polarity, an increased number of photogenerated electrons and a wide band gap for amide COFs were found, hydrophilicity and dispersibility were prompted as well. Both imine and amide COF TFPPy−DP were applied in the photocatalytic reduction and removal of toxic U(VI) under visible light, the catalytic reduction equilibrium (91% removal percentage of 238 ppm U at pH 3) was achieved by imine COFs with 10 h of irradiation, while amide COFs only took 2 h of irradiation (82% removal percentage). The much faster photocatalytic reduction rate of U(VI) can be attributed to the fact that amide COF TFPPy−DP retained crystallinity and permanent porosity and exhibited lower electrochemical impedance and enhanced charge separation and accumulation. Further electronic excitation analysis based on time-dependent density functional theory calculations revealed that the intramolecular charge-transfer effect in amide TFPPy−DP enhanced its photocatalytic rate.

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