Macroscopic and Microscopic Investigation of U(VI) and Eu(III) Adsorption on Carbonaceous Nanofibers

Abstract

The adsorption mechanism of U(VI) and Eu(III) on carbonaceous nanofibers (CNFs) was investigated using batch, IR, XPS, XANES, and EXAFS techniques. The pH-dependent adsorption indicated that the adsorption of U(VI) on the CNFs was significantly higher than the adsorption of Eu(III) at pH < 7.0. The maximum adsorption capacity of the CNFs calculated from the Langmuir model at pH 4.5 and 298 K for U(VI) and Eu(III) were 125 and 91 mg/g, respectively. The CNFs displayed good recyclability and recoverability by regeneration experiments. Based on XPS and XANES analyses, the enrichment of U(VI) and Eu(III) was attributed to the abundant adsorption sites (e.g., -OH and -COOH groups) of the CNFs. IR analysis further demonstrated that -COOH groups were more responsible for U(VI) adsorption. In addition, the remarkable reducing agents of the R-CH2OH groups were responsible for the highly efficient adsorption of U(VI) on the CNFs. The adsorption mechanism of U(VI) on the CNFs at pH 4.5 was shifted from inner- to outer-sphere surface complexation with increasing initial concentration, whereas the surface (co)precipitate (i.e., schoepite) was observed at pH 7.0 by EXAFS spectra. The findings presented herein play an important role in the removal of radionuclides on inexpensive and available carbon-based nanoparticles in environmental cleanup applications.

N, P, and S Codoped Graphene‐Like Carbon Nanosheets for Ultrafast Uranium (VI) Capture with High Capacity

“…According to the survey spectra in Figure 4a, the U(VI)‐adsorbed product maintained all the peaks in the NPS‐GLCs except for two evident peaks at 382.4 and 393.1 eV, which correspond to newly generated U 4f 7/2 and U 4f 5/2 , thereby indicating that a significant number of U(VI) was adsorbed by the NPS‐GLCs 35. The P—O peaks at 133.6 eV and S—O at 168.2 eV in the UO 2 2+ ‐adsorbed NPS‐GLCs increased remarkably as compared to the bare NPS‐GLCs, suggesting that the P and S were oxidized along with UO 2 2+ adsorption 36.…”

Facile preparation and adsorption performance of graphene oxide-manganese oxide composite for uranium

“…) Q m (mg/g)Sorbents (ref. ) Q m (mg/g)AMGO 34 123.40Al 2 O 3 nanofibres 35 204.10Fe-SC 36 148.99Fe 3 O 4 @TiO 2 37 118.80Fe 3 O 4 /GO 38 69.49Layered double oxides/carbon 39 354.2Magnetic cucurbit[6]uril/GO 40 122.50g-C 3 N 4 @Ni-Mg-Al-LDH 41 99.7Oxime-grafted CMK-5 42 62.00 l -C 3 N 4 /PDA/PEI 3 43 60.51Polyacrylamide–hydroxyapatite 44 0.95TiO 2-x 45 65Polypyrrole 46 87.72CaTiO x ; CaAlO x 47 241.7; 258.29Amidoxime modified Fe 3 O 4 @SiO 2 48 105.50Titanate 49 358Modified silica gel 50 90.30CNFs 51 125Birnessite-modified pine biochar 52 47.05p-AO/ CNFs; c-AO/CNFs 53 588.24; 263.18Talc 54 41.60RUB-15 55 152MnO 2 –Fe 3 O 4 –RGO 56 108.70GO-CS-P 57 779.44SA/CMC-Ca-Al 58 101.76Ca/Al-LDH@CNTs 59 382.9Phosphate-modified pine wood sawdust 60 74.10GO (Present study)16.03GOMO (Present study)153.85…”

Biosorption and bioaccumulation behavior of uranium on Bacillus sp. dwc-2: Investigation by Box-Behenken design method

“…It could not only have influence on protonation or deprotonation of functional groups on the cell surface, but also determine the U (VI) speciation in aqueous solution [34,35]. Different pH value (2,3,4,5,6,7) were prepared when other experimental conditions were set as follows: contact time 12 h, cell concentration 10 g/L, uranium initial concentration 5 mg/L and temperature 30°C. Fig.1c illustrated that the highest value of removal efficiency 79.82% was observed when pH was 4.0, where the distribution of uranium species like UO 2 2+ predominate in the solution as calculated and modeled using the Medusa program (Fig.2).…”

“…As a toxic and naturally occurring radionuclide that enters the environment through activities associated with the mining activities, manufacture of nuclear weapons, nuclear energy production and storage of radioactive wastes, uranium (U) can cause ecological contamination, which is serious hazard for human health and damage of bio-organisms [1][2][3][4][5][6]. The presence of uranium in radioactive wastes is of major concern because of its potential for migration from the waste repositories and long-term contamination of the environment.…”