Efficient Photocatalytic Extraction of Uranium over Ethylenediamine Capped Cadmium Sulfide Telluride Nanobelts

Abstract

The photocatalysts for hexavalent uranium (U(VI)) reduction suffered from the low uranium uptake capacity and weak long-wavelength light absorption. Herein, we synthesized the CdS x Te 1−x nanobelts capped by ethylenediamine (EDA), which provided amino groups as the adsorption sites. With the increase of the Te content, the amino groups on the CdS x Te 1−x nanobelts decreased because of the variation of the electron density of Cd 2+ , whereas the light adsorption was enhanced due to the narrowed bandgap. In photocatalytic reduction of U(VI), the CdS 0.95 Te 0.05 -EDA nanobelts exhibited a considerable U(VI) removal ratio of 97.4% with a remarkable equilibrium U(VI) extraction amount on per weight unit of the adsorbent (q e ) of 836 mg/g. The bandgap structure and Fourier transform infrared spectroscopy (FT-IR) spectra analysis revealed that the optimum photocatalytic activity of CdS x Te 1−x nanobelts was achieved at a 5% of Te 2− doping, which balanced the factors of amino groups and bandgap. This adsorption-photoreduction process offers an ultrahigh uranium extraction capacity over wide uranium concentrations.

Ag-Doped CdSe Nanosheets as Photocatalysts for Uranium Reduction

“…Therefore, the changes in the energy band structure of Ag-doped CdSe nanosheets were analyzed using Mott–Schottky, UV diffuse reflection, and UPS. As shown in Figure a, the positive slopes of the three lines indicate that CdSe, 1% Ag-CdSe, and 3% Ag-CdSe nanosheets are n-type semiconductors . In addition, the curves of Ag-doped CdSe nanosheets show a smaller slope, which indicates that the Ag-CdSe nanosheets have a higher carrier density and are more favorable for the transfer of photogenerated carriers .…”

“…As shown in Figure 3a, the positive slopes of the three lines indicate that CdSe, 1% Ag-CdSe, and 3% Ag-CdSe nanosheets are n-type semiconductors. 19 In addition, the curves of Ag-doped CdSe nanosheets show a smaller slope, which indicates that the Ag-CdSe nanosheets have a higher carrier density and are more favorable for the transfer of photogenerated carriers. 40 Noticeably, the photocurrent intensity of 3% Ag-CdSe nanosheets is much higher than the other two samples, which indicates that the introduction of Ag promotes electron transfer and suppresses the photoinduced electron−hole pair recombination significantly 48 (Figure S4a).…”

“…Therefore, the usual method of treating wastewater containing uranium is to reduce soluble U­(VI) to insoluble U­(IV). Compared with conventional treatment methods, the photocatalytic reduction of uranium is considered a promising environmental treatment method because of its advantages such as safety and no secondary pollution. − So far, many semiconductor materials have been creatively used in the photocatalytic reduction of U­(VI), in which the semiconductor can be excited by light irradiation to generate electrons, thereby achieving the reduction of uranium. , …”

“…14−17 So far, many semiconductor materials have been creatively used in the photocatalytic reduction of U(VI), in which the semiconductor can be excited by light irradiation to generate electrons, thereby achieving the reduction of uranium. 18,19 CdSe is an important semiconductor material in the A II -B VI group. 20 It is also considered by many researchers as a very promising two-dimensional nanomaterial that contributes to the photocatalytic reduction of U(VI) because of its large specific surface area, high photostability, and size-dependent band gap.…”

Efficient photoreduction of hexavalent uranium over defective ZnO nanoparticles by oxygen defect engineering

“…Nowadays, the main treatment methods of uranium-bearing radioactive wastewater include extraction, 11 membrane filtration, 12,13 adsorption, [14][15][16][17] biological treatment, 18-22 chemical precipitation, 23 and chemical reduction. [24][25][26] Among them, photoreduction of soluble U(VI) to insoluble uranium (U(IV)) is considered the most environmentally friendly and energy-saving technology to achieve U(VI) extraction. 27,28 However, many conventional semiconductor materials are limited by their wide band gap and narrow visible light response.…”